Selegiline Modulates Lipid Metabolism by Activating AMPK Pathways of Epididymal White Adipose Tissues in HFD-Fed Obese Mice.

Obesity, as a major cause of many chronic diseases such as diabetes, cardiovascular disease, and cancer, is among the most serious health problems. Increased monoamine oxidase (MAO) activity has been observed in the adipose tissue of obese humans and animals. Although previous studies have already demonstrated the potential of MAO-B inhibitors as a treatment for this condition, the mechanism of their effect has been insufficiently elucidated. In this study, we investigated the anti-obesity effect of selegiline, a selective MAO-B inhibitor, using in vivo animal models. The effect was evaluated through an assessment of body energy homeostasis, glucose tolerance tests, and biochemical analysis. Pharmacological inhibition of MAO-B by selegiline was observed to reduce body weight and fat accumulation, and improved glucose metabolism without a corresponding change in food intake, in HFD-fed obese mice. We also observed that both the expression of adipogenenic markers, including C/EBPα and FABP4, and lipogenic markers such as pACC were significantly reduced in epididymal white adipose tissues (eWATs). Conversely, increased expression of lipolytic markers such as ATGL and pHSL and AMPK phosphorylation were noted. Treating obese mice with selegiline significantly increased expression levels of UCP1 and promoted eWAT browning, indicating increased energy expenditure. These results suggest that selegiline, by inhibiting MAO-B activity, is a potential anti-obesity treatment.

Sedative-Hypnotic Activity of the Water Extracts of Coptidis Rhizoma in Rodents.

Many medicinal plants have been used in Asia for treating a variety of mental diseases, including insomnia and depression. However, their sedative-hypnotic effects and mechanisms have not been clarified yet. Accordingly, the objective of this study was to investigate the sedative-hypnotic effects of water extracts of five medicinal plants: Coptidis Rhizoma, Lycii Fructus, Angelicae sinensis Radix, Bupleuri Radix, and Polygonum multiflorum Thunberg. The binding abilities of five medicinal plant extracts to the GABAA-BZD and 5-HT2C receptors were compared. Their abilities to activate arylalkylamine N-acetyltransferase (AANAT), a melatonin synthesis enzyme, in pineal cells were also determined. Following in vitro tests, the sedative and hypnotic activities of extracts with the highest activities were determined in an animal sleep model. In the binding assay, the water extracts of Coptidis Rhizoma (WCR) showed high binding affinity to the GABAA-BZD and 5-HT2C receptors in a dose-dependent manner. Additionally, WCR increased the AANAT activity up to five times compared with the baseline level. Further animal sleep model experiments showed that WCR potentiated pentobarbital-induced sleep by prolonging the sleep time. It also decreased the sleep onset time in mice. In addition, WCR reduced wake time and increased non-rapid eye movement (NREM) sleep without EEG power density (percentages of δ, θ, and α waves) during NREM sleep in rats. WCR could effectively induce NREM sleep without altering the architectural physiologic profile of sleep. This is the first report of the sedative-hypnotic effect of Coptidis Rhizoma possibly by regulating GABAA and 5-HT2C receptors and by activating AANAT activity.

Optogenetic stimulation of the liver-projecting melanocortinergic pathway promotes hepatic glucose production.

The central melanocortin system plays a fundamental role in the control of feeding and body weight. Proopiomelanocortin (POMC) neurons in the arcuate nucleus of the hypothalamus (ARC) also regulate overall glucose homeostasis via insulin-dependent and -independent pathways. Here, we report that a subset of ARC POMC neurons innervate the liver via preganglionic parasympathetic acetylcholine (ACh) neurons in the dorsal motor nucleus of the vagus (DMV). Optogenetic stimulation of this liver-projecting melanocortinergic pathway elevates blood glucose levels that is associated with increased expression of hepatic gluconeogenic enzymes in female and male mice. Pharmacological blockade and knockdown of the melanocortin-4 receptor gene in the DMV abolish this stimulation-induced effect. Activation of melanocortin-4 receptors inhibits DMV cholinergic neurons and optogenetic inhibition of liver-projecting parasympathetic cholinergic fibers increases blood glucose levels. This elevated blood glucose is not due to altered pancreatic hormone release. Interestingly, insulin-induced hypoglycemia increases ARC POMC neuron activity. Hence, this liver-projecting melanocortinergic circuit that we identified may play a critical role in the counterregulatory response to hypoglycemia.

Hydrocarboxylic acid receptor 1 in BAT regulates glucose uptake in mice fed a high-fat diet.

Interscapular brown adipose tissue (BAT) has the capability to take up glucose from the circulation. Despite the important role of BAT in the control of glucose homeostasis, the metabolic fate and function of glucose in BAT remain elusive as there is clear dissociation between glucose uptake and BAT thermogenesis. Interestingly, intracellular glycolysis and lactate production appear to be required for glucose uptake by BAT. Here, we specifically examine whether activation of lactate receptors in BAT plays a key role in regulating glucose homeostasis in mice fed a high-fat diet (HFD). When C57BL/6J mice are given HFD for 5 weeks at 28°C, male, but not female, mice gain body weight and develop hyperglycemia. Importantly, high-fat feeding upregulates expression of the lactate receptor hydroxycarboxylic acid receptor 1 (HCAR1) in female C57BL/6J mice, whereas male C57BL/6J mice show reduced HCAR1 expression in BAT. Treatment with the HCAR1 agonist lowers systemic glucose levels in male DIO mice. This reduction is associated with increased glucose uptake in BAT. Therefore, our results suggest that HCAR1 in BAT may contribute to the development of hyperglycemia in male C57BL/6J DIO mice.

Structural and Functional Alterations at Pre-Epileptic Stage Are Closely Associated with Epileptogenesis in Pilocarpine-induced Epilepsy Model.

Pilocarpine-induced rat epilepsy model is an established animal model that mimics medial temporal lobe epilepsy in humans. The purpose of this study was to investigate neuroimaging abnormalities in various stages of epileptogenesis and to correlate them with seizure severity in pilocarpine-induced rat epilepsy model. Fifty male Sprague-Dawley rats were subject to continuous video and electroencephalographic monitoring after inducing status epilepticus (SE) and seizure severity was estimated by frequency and total durations of class 3 to 5 spontaneous recurrent seizures (SRS) by modified Racine's classification. The 7.0 Tesla magnetic resonance imaging (MRI) with high resolution flurodeoxyglucose positron emission tomography (FDG-PET) was performed at 3 hours, 1, 3, 7 days and 4 weeks after the initial insult. The initial SRS was observed 9.7±1.3 days after the pilocarpine injection. MRI revealed an abnormal T2 signal change with swelling in both hippocampi and amygdala in acute (day 1 after injection) and latent phases (days 3 and 7), in association with PET hypometabolism in these areas. Interestingly, the mean frequency of class 3 to 5 SRS was positively correlated with abnormal T2 signals in hippocampal area at 3 days. SRS duration became longer with more decreased glucose metabolism in both hippocampi and amygdala at 7 days after pilocarpine injection. This study indicates that development and severity of SRS at chronic phase could be closely related with structural and functional changes in hippocampus during the latent period, a pre-epileptic stage.

PET Evidence of the Effect of Donepezil on Cognitive Performance in an Animal Model of Chemobrain.

A considerable number of patients with breast cancer complain of cognitive impairment after chemotherapy. In this study, we showed that donepezil enhanced memory function and increased brain glucose metabolism in a rat model of cognitive impairment after chemotherapy using behavioral analysis and positron emission tomography (PET). We found that chemotherapy affected spatial learning ability, reference memory, and working memory and that donepezil improved these cognitive impairments. According to PET analysis, chemotherapy reduced glucose metabolism in the medial prefrontal cortex and hippocampus, and donepezil increased glucose metabolism in the bilateral frontal lobe, parietal lobe, and hippocampus. Reduced glucose metabolism was more prominent after treatment with doxorubicin than cyclophosphamide. Our results demonstrated the neural mechanisms for cognitive impairment after chemotherapy and show that cognition was improved after donepezil intervention using both behavioral and imaging methods. Our results suggested that donepezil can be employed clinically for the treatment of cognitive deficits after chemotherapy.

Sedative-Hypnotic and Receptor Binding Studies of Fermented Marine Organisms.

This study was performed to investigate the sedative-hypnotic activity of γ-aminobutyric acid (GABA)-enriched fermented marine organisms (FMO), including sea tangle (FST) and oyster (FO) by Lactobacillus brevis BJ20 (L. brevis BJ20). FST and FO were tested for their binding activity of the GABAA-benzodiazepine and 5-HT2C receptors, which are well-known molecular targets for sleep aids. We also measured the sleep latency and sleep duration during pentobarbital-induced sleep in mice after oral administration of FST and FO. In GABAA and 5-HT2C receptor binding assays, FST displayed an effective concentration-dependent binding affinity to GABAA receptor, similar to the binding affinity to 5-HT2C receptor. FO exhibited higher affinity to 5-HT2C receptor, compared with the GABAA receptor. The oral administration of FST and FO produced a dose-dependent decrease in sleep latency and increase in sleep duration in pentobarbital-induced hypnosis. The data demonstrate that FST and FO possess sedative-hypnotic activity possibly by modulating GABAA and 5-HT2C receptors. We propose that FST and FO might be effective agents for treatment of insomnia.

The differential role of NOS inhibitors on stress-induced anxiety and neuroendocrine alterations in the rat.

The inhibitors of nitric oxide synthase (NOS) have been shown to possess antidepressant- and anxiolytic-properties in animal model. In order to examine the involvement of nitric oxide (NO) on stress-induced neurobehavioral changes and the concomitant alterations of neuroendocrinological factors, we studied the effects of the nonselective NOS inhibitor, N(ω)-Nitro L-arginine methyl ester hydrochloride (L-NAME) and the specific neuronal NOS inhibitor, 7-nitroindazole (7-NI) on restraint stress-induced anxiety in the elevated plus maze (EPM) test and biochemical analysis. Restraint stress significantly reduced the latency time in open arm and the percentage of open arm entries of the plus maze. Pretreatment with L-NAME (10 mg/kg) or 7-NI (10 mg/kg) significantly attenuated stress-induced anxiety response. In addition, administration of L-NAME (10 mg/kg) reversed stress-induced increase in corticosterone and NO metabolites (NO(x)) in plasma. The administration of 7-NI, but not L-NAME, reversed stress-induced NO(x) in paraventricular nucleus of the hypothalamus (PVN) and locus coeruleus (LC), accompanying with decrease of NADPH-d reactivity in the PVN and lateral dorsal tegmental nucleus (LTDg). These results showed that L-NAME influences HPA axis activity such as corticosterone levels and NO(x) in plasma, whereas 7-NI produced anxiolytic-like effects through the direct reduction in NO(x) in the brain. The results of this study demonstrated that NOS inhibitors have differential effect on stress responses and inhibition of NO could be responsible for the beneficial effect on regulation of stress.

T-bet deficient mice exhibit resistance to stress-induced development of depression-like behaviors.

T-bet, a Th1-specific T-box transcription factor, regulates Th1 development by inducing endogenous Th1 cytokines and IFN-γ. This study was conducted to determine if T-bet knockout mice exhibit resistance to stress-induced development of depression-like behaviors. The T-bet knockout mice significantly reduced depressive-like behaviors provoked by repeated restraint stress in an elevated plus-maze test (EPM), tail suspension test (TST), and forced swim test (FST). Moreover, stress-induced elevations of the pro-inflammatory cytokines were attenuated in T-bet deficient group. These results suggest that T-bet directly mediated stress-induced depression. Therefore, understanding T-bet function during stress represents an additional treatment strategy for depression.