The effect of inhibiting hindbrain A2 noradrenergic neurons by 6-Hydroxydopamine on lipopolysaccharide-treated male rats autistic animal model.

Autism spectrum disorder (ASD) is a complex neurodevelopmental illness that often emerges in early childhood. The incidence of ASD has shown a notable rise in recent years. ASD is defined by deficits in social communication, and presence of rigid and repetitive behaviors and interests. The underlying mechanisms of ASD remain elusive. Multiple studies have documented the presence of neuroinflammation and increased levels of inflammatory cytokines, specifically, IL-6, TNF, and NF-κB, in various brain regions, including the prefrontal cortex (PFC) and hippocampus in individuals with ASD. Noradrenergic neurons play a crucial role in brain development and the regulation of motor, behavioral, and memory functions. This study sought to examine the impact of intracerebroventricular (icv.) injection of the neurotoxin, 6-hydroxydopamine (6-OHDA), in the caudal dorsal vagal complex A2 neurons on various neuroinflammatory pathways at the hippocampus and PFC in valproic acid (VPA) autistic animal model. This was done in conjunction with an intraperitoneal (i.p.) injection of Lipopolysaccharides (LPS) in animal models with VPA-induced autism. We specifically examined the impact of the caudal fourth ventricle 6-OHDA icv. injection and LPS (i.p.) injection on self-grooming behavior. We measured the mRNA expression of IL-6, TNF-a, and NF-κB using qRT-PCR, and the protein expression of COX-2, GPX-1, p-AMPK, and AMPK using western blot analysis. The self-grooming activity was considerably higher in the combined treatment group (6-OHDA icv. + LPS i.p.) compared to the control group. A substantial increase observed in the expression of IL-6, TNF-α, and NF-κB genes in the PFC of the treatment group that received icv. Administration of 6-OHDA, compared to the control group. The VPA-autism rats that received the combo treatment exhibited a slight increase in the expression level of NF-κB gene in the hippocampus, compared to the control group. At the PFC, we noticed a substantial drop in the expression of the antioxidant protein GPX-1 in the group that received the combo treatment compared to the control group. Our data investigates a novel aspect that the 6-OHDA-induced inhibition of hindbrain A2 neurons could be influencing the neuroinflammatory pathways in the PFC and hippocampus of autistic animal models.

Zerumbone reduces TLR2 stimulation-induced M1 macrophage polarization pattern via upregulation of Nrf-2 expression in murine macrophages.

Hyperuricemia contributes significantly to gout arthritis pathogenesis, which promotes urate crystal deposition in the joints and activates joint-resident macrophages and circulating monocytes to initiate a state of inflammatory arthritis. In the joint, macrophages have an immune defense role where the presence of urate crystals results in the inflammatory mediators secretion, inflammatory cells recruitment to the joint, and shift macrophage population toward M1 pro-inflammatory phenotypes. Current treatment modalities of gout arthritis have side effects that limit their use in the elderly. A novel treatment that targets macrophage polarization to re-establish homeostasis may initiate a drug discovery program of novel disease-modifying agents for gout. Zerumbone (Zer) is a sesquiterpenoid bioactive compound found in the rhizome of Zingiberaceae family and possesses anti-inflammatory, antioxidant, and anti-proliferative activity. Our study hypothesized that soluble uric acid (sUA) and Pam3CSK4 (TLR2 agonist) reduce the anti-inflammatory function of murine M2 bone marrow-derived macrophages and change the expression of M2 genetic markers toward M1 phenotypes. We observed that priming of M2 macrophages with sUA and Pam3CSK4 significantly decreased M2 specific markers expression, e.g., Arg-1, Ym-1, and Fizz-1, enhanced mRNA expression of IL-1ß, TNF-α, CXCL2, and iNOS and increased oxidative stress in M2 macrophages, as exhibited by a reduction in Nrf2 expression. We also aimed to study the impact of Zer on reducing the pro-inflammatory effect of sUA in TLR2-stimulated M2 macrophages. We noticed that Zer treatment significantly reduced L-1ß and TNF-α production following Pam3CSK4 + sUA treatment on M2 macrophages. Furthermore, Zer reduced the caspase-1 activity without altering cytosolic NLRP3 content in challenged M2 BMDMs. We also observed that Zer significantly enhanced M2-associated marker's expression, e.g., Arg-1, Ym-1, and Fizz-1, and augmented Nrf-2 and other antioxidant proteins, including HMOX1 and srxn1expression following Pam3CSK4 + sUA treatment. We draw the conclusion that Zer is a potentially effective anti-inflammatory treatment for gout arthritis linked to hyperuricemia.

Examining the Effects of Dasatinib, Sorafenib, and Nilotinib on Vascular Smooth Muscle Cells: Insights into Proliferation, Migration, and Gene Expression Dynamics.

BACKGROUND: Dasatinib, nilotinib, and sorafenib are clinically proven tyrosine kinase inhibitors (TKIs) used for the treatment of leukemia and hepatocellular carcinoma. However, there is a growing concern regarding cardiotoxicity associated with their use. The impact of these TKIs on vascular smooth muscle cells (VSMCs) remains unexplored. This study aims to investigate the effects of TKIs on VSMC proliferation and migration, as well as to elucidate the underlying mechanisms involving inflammatory and apoptotic pathways. METHODS: VSMCs were extracted from albino rats and cultured in vitro. The cells were divided into four experimental groups: control, dasatinib, sorafenib, and nilotinib. The MTT assay was employed to assess the cytotoxic effects of TKIs on VSMCs. A scratch assay was conducted to evaluate the inhibitory potential of TKIs on VSMC migration. Flow cytometry analysis was used to detect apoptotic cells. Real-Time PCR expression was utilized to determine the differential gene expression of apoptotic and inflammatory markers. RESULTS: Dasatinib, nilotinib, and sorafenib demonstrated significant inhibitory effects on VSMC viability and migration at low concentrations (<1 µmol/L, p < 0.05). Furthermore, gene expression analysis revealed up-regulation of inflammatory biomarkers (TNF-α, IL-6, and IL-1ß) and apoptotic markers (P53, BAX), along with down-regulation of the anti-apoptotic biomarker BCL-2 in response to all TKIs. CONCLUSIONS: This study demonstrates that dasatinib, nilotinib, and sorafenib inhibit VSMC proliferation and migration, suggesting their potential to induce vascular injury and remodeling by activating inflammation and apoptosis pathways. These findings highlight the need for further investigation into the cardiotoxic effects of these TKIs and the development of strategies to mitigate their adverse vascular effects.

Protective role of Dodonaea viscosa extract against streptozotocin-induced hepatotoxicity and nephrotoxicity in rats.

Previous investigations have shown that D. viscosa herbal extract is often used to treat a variety of diseases. Therefore, the purpose of this study was to investigate any additional potential impacts on rat liver and kidney damage induced by diabetes. Streptozotocin (STZ) (60 mg/kg/day) was given as a single dosage to cause type 1 diabetes. After then, diabetic rats received oral doses of D. viscosa for four weeks at 150 and 300 mg/kg/day. Blood, liver, and kidney tissues were collected at the end of the treatment and examined. Analysis was made of the serum lipid profile, liver, and kidney functions, as well as blood biochemistry. Moreover, the levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1ß), prostaglandin E-2 (PGE-2), and nitric oxide (NO) were estimated in serum. In liver and kidney samples, thiobarbituric acid reactive substances (TBARs) and reduced glutathione (GSH), as well as the pro-inflammatory cytokines and enzymatic activities of glutathione peroxidase (GPx), glutathione reeducates (GR), glutathione-S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were analyzed. Histological changes in liver and kidney cross-sections were also observed. Our findings demonstrated that D. viscosa dramatically decreased pro-inflammatory indicators in blood, kidney, and liver tissues as well as blood glucose, and restored insulin levels, and lipid profiles. Additionally, it significantly raises the antioxidant enzyme activity SOD, CAT, GPx, and GST, while significantly lowering TBARs levels. The above-mentioned biochemical changes that took place in tissues were further supported by histological alterations. These findings imply that D. viscosa protects against STZ-induced hyperglycemia, aberrant lipid synthesis, and oxidative stress and that these benefits may be mediated by interacting with various targets to increase the levels of antioxidant enzymes in the liver and kidneys. Its mode of action and safety for use as medicine against various metabolic problems caused by diabetes require more research.

Targeting Store-Operated Calcium Entry Regulates the Inflammation-Induced Proliferation and Migration of Breast Cancer Cells.

Persistent challenges complicating the treatment of breast cancer remain, despite some recent undeniable successes. Sufficient evidence currently exists demonstrating the crucial role of inflammation, characterized by the enhanced activation of Toll-like receptor 4 (TLR4) and the COX-2/PGE2 pathway, in the migration and proliferation of breast cancer cells. Interestingly, the store-operated calcium entry (SOCE) pathway was shown to be essential for the TLR4 activity and COX-2 expression in immune cells such as macrophages and microglia. However, whether SOCE influences inflammatory signaling and the inflammation-induced proliferation and migration of breast cancer cells is still unknown. Thus, the current study intended to delineate the role of SOCE in the TLR4-induced inflammation, migration, and proliferation of breast cancer cells. To this end, MDA-MB-231 breast cancer cells were treated with lipopolysaccharide (LPS) to activate TLR4, BTP2 to inhibit SOCE, and Thapsigargin to induce SOCE. Following these treatments, several experiments were conducted to evaluate the proliferation and migration rates of the MDA-MB-231 cells and the expression of several inflammatory and oncogenic genes, including COX-2, PGE2, IL-6, IL-8, and VEGF. Different techniques were used to achieve the aims of this study, including qRT-PCR, Western blotting, ELISA, MTT, and wound healing assays. This study shows that SOCE inhibition using BTP2 suppressed the LPS-induced migration and proliferation of breast cancer cells. Additionally, treatment with LPS caused approximately six- and three-fold increases in COX-2 mRNA and protein expression, respectively, compared to the controls. The LPS-induced elevations in the COX-2 mRNA and protein levels were suppressed by BTP2 to the control levels. In addition to its effect on COX-2, BTP2 also suppressed the LPS-induced productions of PGE2, IL-6, IL-8, and VEGF. Conversely, SOCE induction using Thapsigargin enhanced the LPS-induced inflammation, migration, and proliferation of breast cancer cells. Collectively, these results provide evidence for the potentially important role of SOCE in inflammation-induced breast cancer progression processes. Thus, we argue that the current study may provide novel targets for designing new therapeutic approaches for the treatment of breast cancer.

Capsaicin Ameliorates the Cyclophosphamide-Induced Cardiotoxicity by Inhibiting Free Radicals Generation, Inflammatory Cytokines, and Apoptotic Pathway in Rats.

Cyclophosphamide is an antineoplastic agent that has a broad range of therapeutic applications; however, it has numerous side effects, including cardiotoxicity. Furthermore, chili peppers contain a substance called capsaicin, having antioxidant and anti-inflammatory effects. Thus, this research paper focuses on the potential mechanism of capsaicin's cardioprotective activity against cyclophosphamide-induced cardiotoxicity by measuring the expression of oxidative and inflammatory marker such as interleukins and caspases. The following groups of rats were randomly assigned: only vehicle given for 6 days (control group); cyclophosphamide 200 mg/kg intraperitoneal on 4th day only (positive control group); capsaicin 10 mg/kg orally given for 6 days followed by cyclophosphamide 200 mg/kg on 4th day of treatment; capsaicin 20 mg/kg orally for six days followed by cyclophosphamide 200 mg/kg on 4th day of treatment; and maximum amount of capsaicin alone (20 mg/kg) orally for six days. Using ELISA kits, it was found that the cyclophosphamide administration significantly increased the levels of lactate dehydrogenase, troponin-I (cardiac cell damage marker), lipid peroxidation, triglyceride, interleukin-6, tumor necrosis factor-alpha, and caspase 3. However, it markedly reduced the antioxidant enzymes catalase and glutathione levels. Both doses of capsaicin could reverse cardiac cell damage markers, as shown by a significant decline in (lactate dehydrogenase and troponin-I). In addition, capsaicin significantly reduced the cytokine levels (interleukin-6 and tumor necrosis factor-alpha), caspase 3, lipid peroxidation, and triglycerides. However, capsaicin treatment significantly raised the antioxidant content of enzymes such as glutathione and catalase. The capsaicin-treated group restored the oxidative parameter's imbalance and generated considerable protection against cardiomyocyte harm from cyclophosphamide in male Wistar rats. These protective effects might be beneficial against the negative impacts of cyclophosphamide when used to treat cancer and immune-mediated diseases.

Blockade of store-operated calcium entry sensitizes breast cancer cells to cisplatin therapy via modulating inflammatory response.

Store-operated calcium entry (SOCE) is an important pathway for calcium signaling that regulates calcium influx across the plasma membrane upon the depletion of calcium stores in the endoplasmic reticulum. SOCE participates in regulating a number of physiological processes including cell proliferation and migration while SOCE dysregulation has been linked with pathophysiological conditions such as inflammation and cancer. The crosslink between cancer and inflammation has been well-established where abundant evidence demonstrate that inflammation plays a role in cancer pathophysiology and the response of cancer cells to chemotherapeutic agents including cisplatin. Indeed, the efficacy of cisplatin against cancer cells is reduced by inflammation. Interestingly, it was shown that SOCE enhances inflammatory signaling in immune cells. Therefore, the main objectives of this study are to examine the impact of SOCE inhibition on the cisplatin sensitivity of breast cancer cells and to explore its related mechanism in modulating the inflammatory response in breast cancer cells. Our findings showed that SOCE inhibitor (BTP2) enhanced cisplatin cytotoxicity against resistant breast cancer cells via inhibition of cell proliferation and migration as well as induction of apoptosis. We also found an upregulation in the gene expression of two major components of SOCE, STIM1 and ORAI1, in cisplatin-resistant breast cancer cells compared to cisplatin-sensitive breast cancer cells. In addition, cisplatin treatment increased the gene expression of STIM1 and ORAI1 in cisplatin-resistant breast cancer cells. Finally, this study also demonstrated that cisplatin therapy caused an increase in the gene expression of inflammatory mediators COX2, IL-8, and TNF-α as well as COX2 protein and upon SOCE inhibition using BTP2, the effect of cisplatin on the inflammatory mediators was reversed. Altogether, this study has proven the pivotal role of SOCE in cisplatin resistance of breast cancer cells and showed the importance of targeting this pathway in improving breast cancer therapy.

Valsartan prevents gefitinib-induced lung inflammation, oxidative stress, and alteration of plasma metabolites in rats.

Gefitinib (GEF) is an inhibitor of the epidermal growth factor receptor, linked to higher risk of severe/fatal interstitial lung disease (ILD). This study was performed to determine the protective roles of an angiotensin-II type-1 receptor (AT1R) "valsartan (VAL)" in prevention of lung inflammation, oxidative stress and metabolites alteration induced by GEF. Four groups of male Wistar albino rats were received vehicle, VAL (30 mg/kg), GEF (30 mg/kg), or both for four weeks. Blood samples and lungs were harvested for plasma metabolites and histological analysis, respectively, and evaluation of inflammation and oxidative stress. GEF monotherapy showed a dense inflammation in lungs, and significantly increased tumor necrosis factor-α (P = 0.0349), interleukin-6 (P < 0.0001), chemokine ligand-3 (P = 0.0420), and interleukin-1ß (P = 0.0377). GEF increased oxidative stress markers including glutathione, malondialdehyde, and catalase levels. Also, several plasma metabolites including butanoic acid, N-methylphenylethanolamine, oxalic acid, l-alanine, phosphoric acid, l-theorinine, pyroglutamic acid, and 2-bromosebacic acid were changed by GEF. The combination of VAL plus GEF reduced the inflammation and oxidative stress mediated by GEF monotherapy. In addition, the combination treatment returned plasma metabolites to the normal levels compared to GEF monotherapy. These findings revealed that VAL has a possible pulmonary protective role against pulmonary toxicity of GEF, which may lead to novel approaches for management of GEF-induced ILD.

Angiotensin II type 1 receptor blockade attenuates gefitinib-induced cardiac hypertrophy via adjusting angiotensin II-mediated oxidative stress and JNK/P38 MAPK pathway in a rat model.

Gefitinib is a tyrosine kinase inhibitor (TKI) of the epidermal growth factor receptor (EGFR), used for the treatment of advanced or metastatic non-small cell lung cancer. Recently, studies proved that Gefitinib-induced cardiotoxicity through induction of oxidative stress leads to cardiac hypertrophy. The current study was conducted to understand the mechanisms underlying gefitinib-induced cardiac hypertrophy through studying the roles of angiotensin II (AngII), oxidative stress, and mitogen-activated protein kinase (MAPK) pathway. Male Wistar albino rats were treated with valsartan, gefitinib, or both for four weeks. Blood samples were collected for AngII and cardiac markers measurement, and hearts were harvested for histological study and biochemical analysis. Gefitinib caused histological changes in the cardiac tissues and increased levels of cardiac hypertrophy markers, AngII and its receptors. Blocking of AngII type 1 receptor (AT1R) via valsartan protected hearts and normalized cardiac markers, AngII levels, and the expression of its receptors during gefitinib treatment. valsartan attenuated gefitinib-induced NADPH oxidase and oxidative stress leading to down-regulation of JNK/p38-MAPK pathway. Collectively, AT1R blockade adjusted AngII-induced NADPH oxidase and JNK/p38-MAPK leading to attenuation of gefitinib-induced cardiac hypertrophy. This study found a pivotal role of AngII/AT1R signaling in gefitinib-induced cardiac hypertrophy, which may provide novel approaches in the management of EGFRIs-induced cardiotoxicity.

Effects of Intracerebroventricular Glycogen Phosphorylase Inhibitor CP-316,819 Infusion on Hypothalamic Glycogen Content and Metabolic Neuron AMPK Activity and Neurotransmitter Expression in Male Rat.

Brain glycogen is a vital energy source during metabolic imbalance. Metabolic sensory neurons in the ventromedial hypothalamic nucleus (VMN) shape glucose counter-regulation. Insulin-induced hypoglycemic (IIH) male rats were infused icv with the glycogen breakdown inhibitor CP-316,819 (CP) to investigate whether glycogen-derived fuel controls basal and/or hypoglycemic patterns of VMN gluco-regulatory neuron energy stability and transmitter signaling. CP caused dose-dependent amplification of basal VMN glycogen content and either mobilization (low dose) or augmentation (high dose) of this depot during IIH. Drug treatment also prevented hypoglycemic diminution of tissue glucose in multiple structures. Low CP dose caused IIH-reversible augmentation of AMPK activity and glutamate decarboxylase (GAD) protein levels in laser-microdissected VMN GABA neurons, while the higher dose abolished hypoglycemic adjustments in these profiles. VMN steroidogenic factor-1 (SF-1) neurons exhibited suppressed (low CP dose) or unchanged (high CP dose) basal SF-1 expression and AMPK refractoriness of hypoglycemia at each dose. CP caused dose-proportionate augmentation of neuronal nitric oxide synthase protein and enhancement (low dose) or diminution (high dose) of this profile during IIH; AMPK activity in these cells was decreased in high dose-pretreated IIH rats. CP exerted dose-dependent effects on basal and hypoglycemic patterns of glucagon, but not corticosterone secretion. Results verify that VMN GABA, SF-1, and nitrergic neurons are metabolic sensory in function and infer that these populations may screen unique aspects of neurometabolic instability. Correlation of VMN glycogen augmentation with attenuated hypoglycemic VMN gluco-regulatory neuron AMPK activity implies that expansion of this fuel reservoir preserves cellular energy stability during this metabolic threat.

Protective Effect of RIVA Against Sunitinib-Induced Cardiotoxicity by Inhibiting Oxidative Stress-Mediated Inflammation: Probable Role of TGF-ß and Smad Signaling.

Sunitinib (SUN) is an oral tyrosine kinase inhibitor approved in 2006 as a first-line treatment for metastatic renal cell cancer. However, weak selectivity to kinase receptors and cardiotoxicity have limited the use of sunitinib. Rivaroxaban (RIVA) is a Factor Xa inhibitor with cardioprotective action. It inhibits atherosclerosis and numerous inflammatory cascades. The present study was designed to investigate the cardioprotective effects of RIVA in sunitinib-induced cardiotoxicity. Thirty male Wistar rats were divided into five groups. Group 1 was the normal control (control). Group 2 was administered i.p. SUN 25 mg kg-1 thrice weekly for 3 weeks. Groups 3 and 4 received the same treatment as Group 2 followed by the administration of RIVA 5 mg kg-1 day-1 and 10 mg kg-1 day-1, respectively, for 3 weeks. Group 5 received only 10 mg kg-1 day-1 RIVA for 3 weeks. Serum levels of Ca2+, Mg2+, Fe3+/Fe2+, lipid profiles, and cardiac enzymes were measured. Cardiac tissues were isolated for the measurements of oxidant/antioxidant balance gene and protein expressions. Relative to the controls, the administration of SUN significantly altered serum levels of (Ca2+, Mg2+, Fe3+/Fe2+, lipid profiles, and cardiac enzymes), intracellular antioxidant enzymes, and the expression levels of the genes encoding certain proteins. RIVA treatment significantly restored these parameters to near-normal levels. RIVA treatment significantly mitigated SUN-induced cardiac injuries by restoring antioxidant enzyme levels and attenuating the proinflammatory cascades resulting from SUN-induced cardiac injuries.

Hindbrain estrogen receptor regulation of ventromedial hypothalamic glycogen metabolism and glucoregulatory transmitter expression in the hypoglycemic male rat.

Estrogen receptor-alpha (ERα) and -beta (ERß) occur in key elements of the brain gluco-homeostatic network in both sexes, including the hindbrain dorsal vagal complex (DVC), but the influence of distinct receptor populations on this critical function is unclear. The ventromedial hypothalamic nucleus (VMN) maintains glucose balance by integrating nutrient, endocrine, and neurochemical cues, including metabolic sensory information supplied by DVC A2 noradrenergic neurons. Current research utilized the selective ERα and ERß antagonists MPP and PHTPP to characterize effects of DVC ERs on VMN norepinephrine (NE) activity and metabolic neurotransmitter signaling in insulin-induced hypoglycemic (IIH) male rats. Data show that ERß inhibits VMN glycogen synthase and stimulates phosphorylase protein expression, while attenuating hypoglycemic augmentation of glycogen content. Furthermore, both ERs attenuate VMN glucose concentrations during IIH. Hypoglycemic up-regulation of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) signaling was correspondingly driven by ERα or -ß, whereas GABA and steroidogenic factor-1 were respectively suppressed independently of ER input or by ERß. IIH intensified VMN NE accumulation by ERß-dependent mechanisms, but did not alter NE levels in other gluco-regulatory loci. ERß amplified the magnitude of insulin-induced decline in blood glucose. Both ERs regulate corticosterone, but not glucagon secretion during IIH and oppose hypoglycemic diminution of circulating free fatty acids. These findings identify distinguishing versus common VMN functions targeted by DVC ERα and -ß. Sex differences in hypoglycemic VMN NE accumulation, glycogen metabolism, and transmitter signaling may involve, in part, discrepant regulatory involvement or differential magnitude of impact of these hindbrain ERs.

Norepinephrine regulation of ventromedial hypothalamic nucleus metabolic transmitter biomarker and astrocyte enzyme and receptor expression: Impact of 5' AMP-activated protein kinase.

The ventromedial hypothalamic energy sensor AMP-activated protein kinase (AMPK) maintains glucostasis via neurotransmitter signals that diminish [γ-aminobutyric acid] or enhance [nitric oxide] counter-regulation. Ventromedial hypothalamic nucleus (VMN) 'fuel-inhibited' neurons are sensitive to astrocyte-generated metabolic substrate stream. Norepinephrine (NE) regulates astrocyte glycogen metabolism in vitro, and hypoglycemia intensifies VMN NE activity in vivo. Current research investigated the premise that NE elicits AMPK-dependent adjustments in VMN astrocyte glycogen metabolic enzyme [glycogen synthase (GS); glycogen phosphorylase (GP)] and gluco-regulatory neuron biomarker [glutamate decarboxylase65/67 (GAD); neuronal nitric oxide synthase (nNOS); SF-1] protein expression in male rats. We also examined whether VMN astrocytes are directly receptive to NE and if noradrenergic input regulates cellular sensitivity to the neuro-protective steroid estradiol. Intra-VMN NE correspondingly augmented or reduced VMN tissue GAD and nNOS protein despite no change in circulating glucose, data that imply that short-term exposure to NE promotes persistent improvement in VMN nerve cell energy stability. The AMPK inhibitor Compound C (Cc) normalized VMN nNOS, GS, and GP expression in NE-treated animals. NE caused AMPK-independent down-regulation of alpha2-, alongside Cc-reversible augmentation of beta1-adrenergic receptor protein profiles in laser-microdissected astrocytes. NE elicited divergent adjustments in astrocyte estrogen receptor-beta (AMPK-unrelated reduction) and GPR-30 (Cc-revocable increase) proteins. Outcomes implicate AMPK in noradrenergic diminution of VMN nitrergic metabolic-deficit signaling and astrocyte glycogen shunt activity. Differentiating NE effects on VMN astrocyte adrenergic and estrogen receptor variant expression suggest that noradrenergic regulation of glycogen metabolism may be mediated, in part, by one or more receptors characterized here by sensitivity to this catecholamine.

Effects of estradiol on lactoprivic signaling of the hindbrain upon the contraregulatory hormonal response and metabolic neuropeptide synthesis in hypoglycemic female rats.

BACKGROUND: Caudal dorsomedial hindbrain detection of hypoglycemia-associated lactoprivation regulates glucose counter-regulation in male rats. In females, estradiol (E) determines hypothalamic neuroanatomical and molecular foci of hindbrain energy sensor activation. This study investigated the hypothesis that E signal strength governs metabolic neuropeptide and counter-regulatory hormone responses to hindbrain lactoprivic stimuli in hypoglycemic female rats. METHODS: Ovariectomized animals were implanted with E-filled silastic capsules [30 (E-30) or 300 µg (E-300)/mL] to replicate plasma concentrations at estrous cycle nadir versus peak levels. E-30 and E-300 rats were injected with insulin or vehicle following initiation of continuous caudal fourth ventricular L-lactate infusion. RESULTS: Hypoglycemic hypercorticosteronemia was greater in E-30 versus E-300 animals. Glucagon and corticosterone outflow was correspondingly fully or partially reversed by hindbrain lactate infusion. Insulin-injected rats exhibited lactate-reversible augmentation of norepinephrine (NE) accumulation in all preoptic/hypothalamic structures examined, excluding the dorsomedial hypothalamic nucleus (DMH) where hindbrain lactate infusion either suppressed (E-30) or enhanced (E-300) NE content. Expression profiles of hypoglycemia-reactive metabolic neuropeptides were normalized (with greater efficacy in E-300 animals) by lactate infusion. DMH RFamide-related peptide-1 and -3, arcuate neuropeptide Y and kisspeptin, and ventromedial nucleus nitric oxide synthase protein responses to hypoglycemia were E dosage-dependent. CONCLUSIONS: Distinct physiological patterns of E secretion characteristic of the female rat estrous cycle elicit differential corticosterone outflow during hypoglycemia, and establish both common and different hypothalamic metabolic neurotransmitter targets of hindbrain lactate deficit signaling. Outcomes emphasize a need for insight on systems-level organization, interaction, and involvement of E signal strength-sensitive neuropeptides in counter-regulatory functions.

Lateral but not Medial Hypothalamic AMPK Activation Occurs at the Hypoglycemic Nadir in Insulin-injected Male Rats: Impact of Caudal Dorsomedial Hindbrain Catecholamine Signaling.

The hypothalamic energy sensor adenosine 5'-monophosphate-activated protein kinase (AMPK), an important regulator of counter-regulatory responses to hypoglycemia, responds to pharmacological manipulation of hindbrain AMPK activity. Dorsomedial hindbrain A2 noradrenergic neurons express hypoglycemia-sensitive metabolo-sensory biomarkers, including AMPK. Here, adult male rats were pretreated by intra-caudal fourth ventricular administration of the selective neurotoxin 6-hydroxydopamine (6-OHDA) to determine if catecholamine signaling from the aforesaid site governs hypothalamic AMPK activation during insulin-induced hypoglycemia (IIH). Micropunched arcuate (ARH), ventromedial (VMH), paraventricular (PVH), dorsomedial (DMH) nuclei and lateral hypothalamic area (LHA) tissues were obtained at the neutral protamine Hagedorn insulin-induced hypoglycemic nadir, coincident with A2 AMPK activation, for Western blot analysis of AMPK, phospho-AMPK (pAMPK), and relevant metabolic neuropeptides. ARH, VMH, LHA, and DMH norepinephrine levels were altered according to insulin dose; 6-OHDA-mediated reversal of these responses was site-specific. IIH elevated LHA and reduced VMH pAMPK protein, profiles that were respectively unchanged or increased by 6-OHDA. PVH and ARH pAMPK was resistant to IIH, but augmented in ARH of neurotoxin- plus insulin-treated rats. ARH neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) proteins were correspondingly increased or refractory to IIH; 6-OHDA pretreatment normalized NPY and elevated POMC expression after insulin injection. Results demonstrate site-specific bi-directional adjustments in hypothalamic AMPK reactivity to hypoglycemia. Intensification of ARH/VMH pAMPK by 6-OHDA implies dorsomedial hindbrain improvement of energy balance in those sites during IIH. Neurotoxin-mediated augmentation versus suppression of basal catabolic (ARH POMC/VMH steroidogenic factor-1) or IIH-associated anabolic (ARH NPY) neuropeptide profiles, respectively, may involve local AMPK-dependent against independent mechanisms.

Hyperglycaemia induced by chronic i.p. and oral glucose loading leads to hypertension through increased Na+ retention in proximal tubule.

NEW FINDINGS: What is the central question of the study? Chronic glucose feeding accompanied by glucose injection (i.p.) causes sustained hyperglycaemia and hypertension in rats. The exact reason for the hypertension is not known. We explore some molecular pathways of the renal proximal tubule that might promote Na+ retention. What is the main finding and its importance? Development of hypertension was mediated by upregulation of the renal renin-angiotensin system and oxidative stress, acting via the Na+ -K+ -ATPase α1 -subunit in the proximal tubule, which appears to pump intracellular Na+ into the extracellular space, increasing Na+ reabsorption and blood pressure. Targeting the Na+ -K+ -ATPase α1 -subunit might provide a therapeutic strategy for treatment of hypertension. Feeding animals glucose-, fructose-, sucrose- and fat-enriched diets can lead to diet-induced hyperglycaemia, the severity of which largely depends on the types and concentrations of the nutrients used and duration of the dietary intervention. As a dietary intervention strategy, we adopted glucose-enriched diet and drinking water, with i.p. glucose injection at a dose previously determined to be effective to establish a sustained hyperglycaemia over a period of 2 weeks. We used four groups of Sprague-Dawley rats: control; glucose treated; glucose plus tempol treated; and glucose plus captopril treated. Blood glucose concentrations started to increase gradually from day 3, peaked (321 mg dl-1 ) at day 12 and remained at similar levels until the end of the study on day 14 in the glucose treated-group compared with the control group. In contrast, the tempol- and captopril-treated groups showed significantly high glucose concentrations only in the second week. The plasma insulin concentration was significantly increased in glucose-treated animals but not in tempol- and captopril-treated groups when compared with the control rats. We also observed elevated blood pressure in the glucose-treated group compared with the control group, which can be attributed to the increase in angiotensin II concentrations from 46.67 to 99 pg ml-1 (control versus glucose), increased oxidative stress in the cortical proximal tubule (PT), decreased urine flow, and increased expression and activity of the PT-specific α1 -subunit of Na+ -K+ -ATPase in the renal cortex, which is responsible for increased sodium reabsorption from epithelial cells of PT into the peritubular capillaries, leading to increased blood volume and eventual blood pressure. All these events were reversed in captopril- and tempol-treated animals.

Inhibition of glycogen phosphorylase stimulates ventromedial hypothalamic nucleus AMP-activated protein kinase: Activity and neuronal nitric oxide synthase protein expression in male rats.

The glucose polymer glycogen is a vital fuel reserve in the brain. The mediobasal hypothalamic energy sensor AMP-activated protein kinase (AMPK) maintains glucostasis via neurotransmitter mechanisms that suppress [γ-aminobutyric acid; GABA] or stimulate [nitric oxide; steroidogenic factor-1 (SF1)] counter-regulatory outflow. This study investigated whether glycogen-derived fuel supply is a critical screened variable in ventromedial hypothalamic nucleus (VMN) monitoring of neuro-metabolic stability during glucostasis and/or insulin (I)-induced hypoglycemia. Adult male rats were pretreated by intra-VMN infusion of the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) before sc vehicle or I injection. Western blot analyses of micropunch-dissected VMN tissue from euglycemic animals showed DAB augmentation of phosphoAMPK (pAMPK), neuronal nitric oxide synthase (nNOS), and SF-1, but not glutamate decarboxylase65/67 (GAD) protein. Combinatory DAB/I treatment did not further enhance AMPK activity but significantly amplified nNOS expression relative to DAB alone. Hypoglycemic stimulation of corticosterone, but not glucagon release was prevented by DAB Results imply that glycogen-derived substrate fuel provision represses VMN AMPK activity and neurotransmitter signals of metabolic deficiency. Progressive augmentation of nNOS protein by DAB/I versus DAB/V intimates that "fuel-inhibited" nitrergic neurons may exhibit increasing sensitivity to disrupted glycogen breakdown during glucoprivation versus glucostasis. nNOS and GAD reactivity to DAB/I, but not I implies that acute glycogen utilization during hypoglycemia may be sufficiently robust to avert effects on local metabolic sensory signaling. DAB/I upregulation of GAD alongside prevention of hypercorticosteronemia suggests that indicators of metabolic sufficiency may occur secondary to local compensatory adaptations to severe restriction of glucose-derived energy.

Sex Differences and Role of Estradiol in Hypoglycemia-Associated Counter-Regulation.

Vital nerve cell functions, including maintenance of transmembrane voltage and information transfer, occur at high energy expense. Inadequate provision of the obligate metabolic fuel glucose exposes neurons to risk of dysfunction or injury. Clinical hypoglycemia rarely occurs in nondiabetic individuals but is an unfortunate regular occurrence in patients with type 1 or advanced insulin-treated type 2 diabetes mellitus. Requisite strict glycemic control, involving treatment with insulin, sulfonylureas, or glinides, can cause frequent episodes of iatrogenic hypoglycemia due to defective counter-regulation, including reduced glycemic thresholds and diminished magnitude of motor responses. Multiple components of the body's far-reaching energy balance regulatory network, including the hindbrain dorsal vagal complex, provide dynamic readout of cellular energetic disequilibrium, signals that are utilized by the hypothalamus to shape counterregulatory autonomic, neuroendocrine, and behavioral outflow toward restoration of glucostasis. The ovarian steroid hormone 17ß-estradiol acts on central substrates to preserve nerve cell energy stability brain-wide, thereby providing neuroprotection against bio-energetic insults such as neurodegenerative diseases and acute brain ischemia. The current review highlights recent evidence implicating estrogen in gluco-regulation in females by control of hindbrain metabolic sensor screening and signaling of hypoglycemia-associated neuro-energetic instability. It is anticipated that new understanding of the mechanistic basis of how estradiol influences metabolic sensory input from this critical brain locus to discrete downstream regulatory network substrates will likely reveal viable new molecular targets for therapeutic simulation of hormone actions that promote positive neuronal metabolic state during acute and recurring hypoglycemia.

Role of hindbrain adenosine 5'-monophosphate-activated protein kinase (AMPK) in hypothalamic AMPK and metabolic neuropeptide adaptation to recurring insulin-induced hypoglycemia in the male rat.

Glucose counter-regulatory dysfunction correlates with impaired activation of the hypothalamic metabolic sensor adenosine 5'-monophosphate-activated protein kinase (AMPK). Hypothalamic AMPK is controlled by hindbrain energy status; we examined here whether hindbrain AMPK regulates hypothalamic AMPK and metabolic neurotransmitter maladaptation to recurring insulin-induced hypoglycemia (RIIH). Brain tissue was harvested after single versus serial insulin (I) dosing for Western blot analysis of AMPK, phospho-AMPK (pAMPK), and relevant biosynthetic enzyme/neuropeptide expression in micro-punch dissected arcuate (ARH), ventromedial (VMH), dorsomedial (DMH) nuclei and lateral hypothalamic area (LHA) tissue. The AMPK inhibitor compound c (Cc) or vehicle was administered to the caudal fourth ventricle ahead of antecedent I injections. RIIH caused site-specific elevation (ARH, VMH, LHA) or reduction (DMH) of total AMPK protein versus acute hypoglycemia; Cc respectively exacerbated or attenuated this response in the ARH and VMH. Hindbrain AMPK correspondingly inhibited or stimulated LHA and DMH pAMPK expression during RIIH. RIIH elicited Cc-reversible augmentation of VMH glutamate decarboxylase profiles, but stimulated (ARH pro-opiomelanocortin; LHA orexin-A) or decreased (VMH nitric oxide synthase) other metabolic neurotransmitters without hindbrain sensor involvement. Results demonstrate acclimated up-regulation of total AMPK protein expression in multiple hypothalamic loci during RIIH, and document hindbrain sensor contribution to amplification of this protein profile in the VMH. Concurrent lack of net change in ARH and VMH tissue pAMPK implies adaptive reductions in local sensor activity, which may/may not reflect positive gain in energy state. It remains unclear if 'glucose-excited' VMH GABAergic and/or ARH pro-opiomelanocortin neurons exhibit AMPK habituation to RIIH, and whether diminished sensor activation in these and other mediobasal hypothalamic neurotransmitter populations may contribute to HAAF.