Novel Techniques for Mapping DNA Damage and Repair in the Brain.

DNA damage in the brain is influenced by endogenous processes and metabolism along with exogenous exposures. Accumulation of DNA damage in the brain can contribute to various neurological disorders, including neurodegenerative diseases and neuropsychiatric disorders. Traditional methods for assessing DNA damage in the brain, such as immunohistochemistry and mass spectrometry, have provided valuable insights but are limited by their inability to map specific DNA adducts and regional distributions within the brain or genome. Recent advancements in DNA damage detection methods offer new opportunities to address these limitations and further our understanding of DNA damage and repair in the brain. Here, we review emerging techniques offering more precise and sensitive ways to detect and quantify DNA lesions in the brain or neural cells. We highlight the advancements and applications of these techniques and discuss their potential for determining the role of DNA damage in neurological disease.

Exercise modulates APOE expression in brain cortex of female APOE3 and APOE4 targeted replacement mice.

Apolipoprotein E (ApoE) is the main cholesterol carrier of the brain and the ε4 gene variant (APOE4) is the most prevalent genetic risk factor for Alzheimer's disease (AD), increasing risk up to 15-fold. Several studies indicate that APOE4 modulates critical factors for neuronal function, including brain-derived neurotrophic factor (BDNF) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α). Both proteins show exercise-induced upregulation, which is presumed to mediate many of the beneficial effects of physical activity including improved cognition; however, there is variability in results between individuals potentially in-part due to genetic variations including APOE isoform. This study aimed to determine if the two most prevalent human APOE isoforms influence adaptive responses to exercise-training. Targeted replacement mice, homozygous for either APOE3 or APOE4 were randomized into exercised and sedentary groups. Baseline locomotor function and voluntary wheel-running behavior was reduced in APOE4 mice. Exercised groups were subjected to daily treadmill running for 8 weeks. ApoE protein in brain cortex was significantly increased by exercise in both genotypes. PGC-1α mRNA levels in brain cortex were significantly lower in APOE4 mice, and only tended to increase with exercise in both genotypes. Hippocampal BDNF protein were similar between genotypes and was not significantly modulated by treadmill running. Behavioral and biochemical variations between APOE3 and APOE4 mice likely contribute to the differential risk for neurological and vascular diseases and the exercise-induced increase in ApoE levels suggests an added feature of the potential efficacy of physical activity as a preventative and therapeutic strategy for neurogenerative processes in both genotypes.

Strategies for developing a recombinant butyrylcholinesterase medical countermeasure for Organophosphorus poisoning.

Organophosphorus nerve agents represent a serious chemical threat due to their ease of production and scale of impact. The recent use of the nerve agent Novichok has re-emphasised the need for broad-spectrum medical countermeasures (MCMs) to these agents. However, current MCMs are limited. Plasma derived human butyrylcholinesterase (huBChE) is a promising novel bioscavenger MCM strategy, but is prohibitively expensive to isolate from human plasma at scale. Efforts to produce recombinant huBChE (rBChE) in various protein expression platforms have failed to achieve key critical attributes of huBChE such as circulatory half-life. These proteins often lack critical features such as tetrameric structure and requisite post-translational modifications. This review evaluates previous attempts to generate rBChE and assesses recent advances in mammalian cell expression and protein engineering strategies that could be deployed to achieve the required half-life and yield for a viable rBChE MCM. This includes the addition of a proline-rich attachment domain, fusion proteins, post translational modifications, expression system selection and optimised downstream processes. Whilst challenges remain, a combinatorial application of these strategies demonstrates potential as a technically feasible approach to achieving a bioactive and cost effective bioscavenger MCM.

Impacts of sex and the estrous cycle on associations between post-fear conditioning sleep and fear memory recall.

Women are at greater risk than men for developing posttraumatic stress disorder (PTSD) after trauma exposure. Sleep, especially rapid-eye-movement sleep (REMS), has been considered a contributing factor to the development of PTSD symptoms through its effects on the processing of emotional memories. However, it remains unknown if sex and sex hormones play a role in the hypothesized impact of sleep on the development of PTSD. Animal models have methodological advantages over human studies in investigating this research question; however, animal models of sleep in PTSD have been tested only with males. C57BL/6 mice (7 males and 15 females) were exposed to 15 footshocks in a footshock chamber, and 5 min after the last footshock, were returned to their home cages for telemetric electroencephalographic sleep recording. Nine to thirteen days later, mice were returned to the footshock chamber for 10 min without footshocks. Fear recall rates were computed by comparing freezing behaviors in the footshock chamber immediately after the footshocks to those during fear context reexposure. Males had significantly lower recall rates compared to metestrous females (that received footshocks on metestrus). Overall, males slept more than both proestrous females (that received footshocks on proestrus) and metestrous females during the dark period. Regression analyses revealed that average REMS episode durations after footshocks were differentially associated with recall rates across groups, such that the association was positive in males, but negative in proestrous females. Results suggest that both sex and the estrous cycle modulate the associations between REMS continuity and fear memory consolidation.

Exercise Training Induced Changes In Nuclear Magnetic Resonance-Measured Lipid Particles In Mild Cognitively Impaired Elderly African American Volunteers: A Pilot Study.

PURPOSE: Poor cardiorespiratory fitness (CRF) is linked to cognitive deterioration, but its effects on lipid heterogeneity and functional properties in older African American (AA) subjects with mild cognitive impairment (MCI) need elucidation. This study determined whether exercise training-induced changes in blood lipid particle sizes (LPS) were associated with CRF determined by VO2Max in elderly AAs with MCI. Given the pivotal role of brain-derived neurotrophic factor (BDNF) on glucose metabolism, and therefore, "diabetic dyslipidemia", we also determined whether changes in LPS were associated with the levels of serum BDNF. METHODS: This analysis included 17 of the 29 randomized elderly AAs with MCI who had NMR data at baseline and after a 6-month training. We used Generalized Linear Regression (GLM) models to examine cardiorespiratory fitness (VO2Max) effects on training-induced change in LPS in the stretch and aerobic groups. Additionally, we determined whether the level of BDNF influenced change in LPS. RESULTS: Collectively, mean VO2Max (23.81±6.17) did not differ significantly between aerobic and stretch groups (difference=3.17±3.56, P=0.495). Training-related changes in very low-density lipoprotein, chylomicrons, and total low-density lipoprotein (LDL) particle sizes correlated significantly with VO2Max, but not after adjustment for age and gender. However, increased VO2Max significantly associated with reduced total LDL particle size after similar adjustments (P = 0.046). While stretch exercise associated with increased protective large high-density lipoprotein particle size, the overall effect was not sustained following adjustments for gender and age. However, changes in serum BDNF were associated with changes in triglyceride and cholesterol transport particle sizes (P < 0.051). CONCLUSION: Promotion of stretch and aerobic exercise to increase CRF in elderly AA volunteers with MCI may also promote beneficial changes in lipoprotein particle profile. Because high BDNF concentration may reduce CVD risk, training-related improvements in BDNF levels are likely advantageous. Large randomized studies are needed to confirm our observations and to further elucidate the role for exercise therapy in reducing CVD risk in elderly AAs with MCI.

Associations of Pulse and Blood Pressure with Hippocampal Volume by APOE and Cognitive Phenotype: The Alzheimer's Disease Neuroimaging Initiative (ADNI).

BACKGROUND: It is increasingly evident that high blood pressure can promote reduction in global and regional brain volumes. While these effects may preferentially affect the hippocampus, reports are inconsistent. METHODS: Using data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), we examined the relationships of hippocampal volume to pulse pressure (PPR) and systolic (SBP) and diastolic (DBP) blood pressure according to apolipoprotein (APOE) ɛ4 positivity and cognitive status. The ADNI data included 1,308 participants: Alzheimer disease (AD = 237), late mild cognitive impairment (LMCI = 454), early mild cognitive impairment (EMCI = 254), and cognitively normal (CN = 365), with up to 24 months of follow-up. RESULTS: Higher quartiles of PPR were significantly associated with lower hippocampal volumes (Q1 vs. Q4, p = 0.034) in the CN and AD groups, but with increasing hippocampal volume (Q1, p = 0.008; Q2, p = 0.020; Q3, p = 0.017; Q4 = reference) in the MCI groups. In adjusted stratified analyses among non-APOE ɛ4 carriers, the effects in the CN (Q1 vs. Q4, p = 0.006) and EMCI groups (Q1, p = 0.002; Q2, p = 0.013; Q3, p = 0.002; Q4 = reference) remained statistically significant. Also, higher DBP was significantly associated with higher hippocampal volume (p = 0.002) while higher SBP was significantly associated with decreasing hippocampal volume in the EMCI group (p = 0.015). CONCLUSION: Changes in PPR, SBP, and DBP differentially influenced hippocampal volumes depending on the cognitive and APOE genotypic categories.

The Role of Hypoxia-Inducible Factor 1 in Mild Cognitive Impairment.

Neuroinflammation and reactive oxygen species are thought to mediate the pathogenesis of Alzheimer's disease (AD), suggesting that mild cognitive impairment (MCI), a prodromal stage of AD, may be driven by similar insults. Several studies document that hypoxia-inducible factor 1 (HIF-1) is neuroprotective in the setting of neuronal insults, since this transcription factor drives the expression of critical genes that diminish neuronal cell death. HIF-1 facilitates glycolysis and glucose metabolism, thus helping to generate reductive equivalents of NADH/NADPH that counter oxidative stress. HIF-1 also improves cerebral blood flow which opposes the toxicity of hypoxia. Increased HIF-1 activity and/or expression of HIF-1 target genes, such as those involved in glycolysis or vascular flow, may be an early adaptation to the oxidative stressors that characterize MCI pathology. The molecular events that constitute this early adaptation are likely neuroprotective, and might mitigate cognitive decline or the onset of full-blown AD. On the other hand, prolonged or overwhelming stressors can convert HIF-1 into an activator of cell death through agents such as Bnip3, an event that is more likely to occur in late MCI or advanced Alzheimer's dementia.

APOEε4 impacts up-regulation of brain-derived neurotrophic factor after a six-month stretch and aerobic exercise intervention in mild cognitively impaired elderly African Americans: A pilot study.

Possession of the Apolipoprotein E (APOE) gene ε4 allele is the most prevalent genetic risk factor for late onset Alzheimer's disease (AD). Recent evidence suggests that APOE genotype differentially affects the expression of brain-derived neurotrophic factor (BDNF). Notably, aerobic exercise-induced upregulation of BDNF is well documented; and exercise has been shown to improve cognitive function. As BDNF is known for its role in neuroplasticity and survival, its upregulation is a proposed mechanism for the neuroprotective effects of physical exercise. In this pilot study designed to analyze exercise-induced BDNF upregulation in an understudied population, we examined the effects of APOEε4 (ε4) carrier status on changes in BDNF expression after a standardized exercise program. African Americans, age 55years and older, diagnosed with mild cognitive impairment participated in a six-month, supervised program of either stretch (control treatment) or aerobic (experimental treatment) exercise. An exercise-induced increase in VO2Max was detected only in male participants. BDNF levels in serum were measured using ELISA. Age, screening MMSE scores and baseline measures of BMI, VO2Max, and BDNF did not differ between ε4 carriers and non-ε4 carriers. A significant association between ε4 status and serum BDNF levels was detected. Non-ε4 carriers showed a significant increase in BDNF levels at the 6month time point while ε4 carriers did not. We believe we have identified a relationship between the ε4 allele and BDNF response to physiologic adaptation which likely impacts the extent of neuroprotective benefit gained from engagement in physical exercise. Replication of our results with inclusion of diverse racial cohorts, and a no-exercise control group will be necessary to determine the scope of this association in the general population.

Resveratrol supplementation confers neuroprotection in cortical brain tissue of nonhuman primates fed a high-fat/sucrose diet.

Previous studies have shown positive effects of long-term resveratrol (RSV) supplementation in preventing pancreatic beta cell dysfunction, arterial stiffening and metabolic decline induced by high-fat/high-sugar (HFS) diet in nonhuman primates. Here, the analysis was extended to examine whether RSV may reduce dietary stress toxicity in the cerebral cortex of the same cohort of treated animals. Middle-aged male rhesus monkeys were fed for 2 years with HFS alone or combined with RSV, after which whole-genome microarray analysis of cerebral cortex tissue was carried out along with ELISA, immunofluorescence, and biochemical analyses to examine markers of vascular health and inflammation in the cerebral cortices. A number of genes and pathways that were differentially modulated in these dietary interventions indicated an exacerbation of neuroinflammation (e.g., oxidative stress markers, apoptosis, NF-κB activation) in HFS-fed animals and protection by RSV treatment. The decreased expression of mitochondrial aldehyde dehydrogenase 2, dysregulation in endothelial nitric oxide synthase, and reduced capillary density induced by HFS stress were rescued by RSV supplementation. Our results suggest that long-term RSV treatment confers neuroprotection against cerebral vascular dysfunction during nutrient stress.

Stereological analyses of reward system nuclei in maternally deprived/separated alcohol drinking rats.

The experience of early life stress can trigger complex neurochemical cascades that influence emotional and addictive behaviors later in life in both adolescents and adults. Recent evidence suggests that excessive alcohol drinking and drug-seeking behavior, in general, are co-morbid with depressive-like behavior. Both behaviors are reported in humans exposed to early life adversity, and are prominent features recapitulated in animal models of early life stress (ELS) exposure. Currently, little is known about whether or how ELS modulates reward system nuclei. In this study we use operant conditioning of rats to show that the maternal separation stress (MS) model of ELS consumes up to 3-fold greater quantities of 10% vol/vol EtOH in 1-h, consistently over a 3-week period. This was correlated with a significant 22% reduction in the number of dopaminergic-like neurons in the VTA of naïve MS rats, similar to genetically alcohol-preferring (P) rats which show a 35% reduction in tyrosine hydroxylase (TH)-positive dopaminergic neurons in the VTA. MS rats had a significantly higher 2-fold immobility time in the forced swim test (FST) and reduced sucrose drinking compared to controls, indicative of depressive-like symptomology and anhedonia. Consistent with this finding, stereological analysis revealed that amygdala neurons were 25% greater in number at P70 following MS exposure. Our previous examination of the dentate gyrus of hippocampus, a region involved in encoding emotional memory, revealed fewer dentate gyrus neurons after MS, but we now report this reduction in neurons occurs without effect on the number of astrocytes or length of astrocytic fibers. These data indicate that MS animals exhibit neuroanatomical changes in reward centers similar to those reported for high alcohol drinking rats, but aspects of astrocyte morphometry remained unchanged. These data are of high relevance to understand the breadth of neuronal pathology that ensues in reward loci following ELS.

Prolonged metformin treatment leads to reduced transcription of Nrf2 and neurotrophic factors without cognitive impairment in older C57BL/6J mice.

Long-term use of anti-diabetic agents has become commonplace as rates of obesity, metabolic syndrome and diabetes continue to escalate. Metformin, a commonly used anti-diabetic drug, has been shown to have many beneficial effects outside of its therapeutic regulation of glucose metabolism and insulin sensitivity. Studies on metformin's effects on the central nervous system are limited and predominantly consist of in vitro studies and a few in vivo studies with short-term treatment in relatively young animals; some provide support for metformin as a neuroprotective agent while others show evidence that metformin may be deleterious to neuronal survival. In this study, we examined the effect of long-term metformin treatment on brain neurotrophins and cognition in aged male C57Bl/6 mice. Mice were fed control (C), high-fat (HF) or a high-fat diet supplemented with metformin (HFM) for 6 months. Metformin decreased body fat composition and attenuated declines in motor function induced by a HF diet. Performance in the Morris water maze test of hippocampal based memory function, showed that metformin prevented impairment of spatial reference memory associated with the HF diet. Quantitative RT-PCR on brain homogenates revealed decreased transcription of BDNF, NGF and NTF3; however protein levels were not altered. Metformin treatment also decreased expression of the antioxidant pathway regulator, Nrf2. The decrease in transcription of neurotrophic factors and Nrf2 with chronic metformin intake, cautions of the possibility that extended metformin use may alter brain biochemistry in a manner that creates a vulnerable brain environment and warrants further investigation.

A standardized randomized 6-month aerobic exercise-training down-regulated pro-inflammatory genes, but up-regulated anti-inflammatory, neuron survival and axon growth-related genes.

There is considerable support for the view that aerobic exercise may confer cognitive benefits to mild cognitively impaired elderly persons. However, the biological mechanisms mediating these effects are not entirely clear. As a preliminary step towards informing this gap in knowledge, we enrolled older adults confirmed to have mild cognitive impairment (MCI) in a 6-month exercise program. Male and female subjects were randomized into a 6-month program of either aerobic or stretch (control) exercise. Data collected from the first 10 completers, aerobic exercise (n=5) or stretch (control) exercise (n=5), were used to determine intervention-induced changes in the global gene expression profiles of the aerobic and stretch groups. Using microarray, we identified genes with altered expression (relative to baseline values) in response to the 6-month exercise intervention. Genes whose expression were altered by at least two-fold, and met the p-value cutoff of 0.01 were inputted into the Ingenuity Pathway Knowledge Base Library to generate gene-interaction networks. After a 6-month aerobic exercise-training, genes promoting inflammation became down-regulated, whereas genes having anti-inflammatory properties and those modulating immune function or promoting neuron survival and axon growth, became up-regulated (all fold change≥±2.0, p<0.01). These changes were not observed in the stretch group. Importantly, the differences in the expression profiles correlated with significant improvement in maximal oxygen uptake (VO2max) in the aerobic program as opposed to the stretch group. We conclude that three distinct cellular pathways may collectively influence the training effects of aerobic exercise in MCI subjects. We plan to confirm these effects using rt-PCR and correlate such changes with the cognitive phenotype.

Alcohol Withdrawal-Induced Seizure Susceptibility is Associated with an Upregulation of CaV1.3 Channels in the Rat Inferior Colliculus.

BACKGROUND: We previously reported increased current density through L-type voltage-gated Ca(2+) (CaV1) channels in inferior colliculus (IC) neurons during alcohol withdrawal. However, the molecular correlate of this increased CaV1 current is currently unknown. METHODS: Rats received three daily doses of ethanol every 8 hours for 4 consecutive days; control rats received vehicle. The IC was dissected at various time intervals following alcohol withdrawal, and the mRNA and protein levels of the CaV1.3 and CaV1.2 α1 subunits were measured. In separate experiments, rats were tested for their susceptibility to alcohol withdrawal-induced seizures (AWS) 3, 24, and 48 hours after alcohol withdrawal. RESULTS: In the alcohol-treated group, AWS were observed 24 hours after withdrawal; no seizures were observed at 3 or 48 hours. No seizures were observed at any time in the control-treated rats. Compared to control-treated rats, the mRNA level of the CaV1.3 α1 subunit was increased 1.4-fold, 1.9-fold, and 1.3-fold at 3, 24, and 48 hours, respectively. In contrast, the mRNA level of the CaV1.2 α1 subunit increased 1.5-fold and 1.4-fold at 24 and 48 hours, respectively. At 24 hours, Western blot analyses revealed that the levels of the CaV1.3 and CaV1.2 α1 subunits increased by 52% and 32%, respectively, 24 hours after alcohol withdrawal. In contrast, the CaV1.2 and CaV1.3 α1 subunits were not altered at either 3 or 48 hours during alcohol withdrawal. CONCLUSIONS: Expression of the CaV1.3 α1 subunit increased in parallel with AWS development, suggesting that altered L-type CaV1.3 channel expression is an important feature of AWS pathogenesis.

Age-related brain expression and regulation of the chemokine CCL4/MIP-1ß in APP/PS1 double-transgenic mice.

The detrimental effect of activation of the chemokine CCL4/MIP-1ß on neuronal integrity in patients with HIV-associated dementia has directed attention to the potential role of CCL4 expression and regulation in Alzheimer disease. Here, we show that CCL4 mRNA and protein are overexpressed in the brains of APPswe/PS1ΔE9 (APP/PS1) double-transgenic mice, a model of cerebral amyloid deposition; expression was minimal in brains from nontransgenic littermates or single-mutant controls. Increased levels of CCL4 mRNA and protein directly correlated with the age-related progression of cerebral amyloid-ß (Aß) levels in APP/PS1 mice. We also found significantly increased expression of activating transcription factor 3 (ATF3), which was positively correlated with age-related Aß deposition and CCL4 in the brains of APP/PS1 mice. Results from chromatin immunoprecipitation-quantitative polymerase chain reaction confirmed that ATF3 binds to the promoter region of the CCL4 gene, consistent with a potential role in regulating CCL4 transcription. Finally, elevated ATF3 mRNA expression in APP/PS1 brains was associated with hypomethylation of the ATF3 gene promoter region. These observations prompt the testable hypothesis for future study that CCL4 overexpression, regulated in part by hypomethylation of the ATF3 gene, may contribute to neuropathologic progression associated with amyloid deposition in Alzheimer disease.

Resveratrol improves adipose insulin signaling and reduces the inflammatory response in adipose tissue of rhesus monkeys on high-fat, high-sugar diet.

Obesity is associated with a chronic, low-grade, systemic inflammation that may contribute to the development of insulin resistance and type 2 diabetes. Resveratrol, a natural compound with anti-inflammatory properties, is shown to improve glucose tolerance and insulin sensitivity in obese mice and humans. Here, we tested the effect of a 2-year resveratrol administration on proinflammatory profile and insulin resistance caused by a high-fat, high-sugar (HFS) diet in white adipose tissue (WAT) from rhesus monkeys. Resveratrol supplementation (80 and 480 mg/day for the first and second year, respectively) decreased adipocyte size, increased sirtuin 1 expression, decreased NF-κB activation, and improved insulin sensitivity in visceral, but not subcutaneous, WAT from HFS-fed animals. These effects were reproduced in 3T3-L1 adipocytes cultured in media supplemented with serum from monkeys fed HFS ± resveratrol diets. In conclusion, chronic administration of resveratrol exerts beneficial metabolic and inflammatory adaptations in visceral WAT from diet-induced obese monkeys.

Treatment with bexarotene, a compound that increases apolipoprotein-E, provides no cognitive benefit in mutant APP/PS1 mice.

BACKGROUND: Though the precise cause(s) of Alzheimer's disease (AD) remain unknown, there is strong evidence that decreased clearance of ß-amyloid (Aß) from the brain can contribute to the disease. Therapeutic strategies to promote natural Aß clearance mechanisms, such as the protein apolipoprotein-E (APOE), hold promise for the treatment of AD. The amount of APOE in the brain is regulated by nuclear receptors including retinoid X receptors (RXRs). Drugs that activate RXRs, including bexarotene, can increase APOE and ABCA1 production, and have been shown to decrease the Aß burden and improve cognition in mouse models of Aß amyloidosis. Although recent bexarotene studies failed to replicate the rapid clearance of Aß from brains, behavioral and cognitive effects of this compound remain controversial. FINDINGS: In efforts to clarify these behavioral findings, mutant APP/PS1 mice were acutely dosed with bexarotene. While ABCA1 was upregulated in mutant APP/PS1 mice treated with bexarotene, this drug failed to attenuate Aß plaques or cognitive deficits in these mice. CONCLUSIONS: We recommend rigorous preclinical study to evaluate the mechanism and utility of such a compound for AD therapy.

Neuronal expression of bitter taste receptors and downstream signaling molecules in the rat brainstem.

Previous studies have shown that molecules of the taste transduction pathway may serve as biochemical markers for chemoreceptive cells in respiratory and gastrointestinal tracts. In this study, we tested the hypothesis that brainstem neurons contain signaling molecules similar to those in taste buds which may sense the chemical composition of brain extracellular fluids. We used the reverse transcription polymerase chain reaction (RT-PCR), Western blot and immunohistochemical techniques to evaluate presence of different bitter-responsive type 2 taste receptors (T2Rs), their associated G-protein α-gustducin, the downstream signaling molecules phospholipase C isoform ß2 (PLC-ß2) and transient receptor potential melastatin 5 (TRPM5) in the brainstem of rats. RT-PCR confirmed the mRNA coding for α-gustducin, PLC-ß2, TRPM5 and rT2R1 but not that of rT2R16, rT2R26 and rT2R38 in the medulla oblongata. Western blotting confirmed the presence of α-gustducin at the protein level in rat brainstem. Immunohistochemistry identified cells expressing α-gustducin and PLC-ß2 at multiple cardiorespiratory and CO(2)/H(+) chemosensory sites, including rostral ventral medulla, facial, parapyramidal, solitary tract, hypoglossal and raphe nuclei. In the medullary raphe, α-gustducin and PLC-ß2 were colocalized with a subpopulation of tryptophan hydroxylase (TPH)-immunoreactive serotonergic neurons, a subset of which has respiratory CO(2)/H(+) chemosensitivity. Presence of the T2R1 gene and other genes and proteins of the bitter taste transduction pathway in the brainstem implies additional functions for taste receptors and their effector molecules apart from their gustatory function.

Selective rapid eye movement sleep deprivation affects cell size and number in kitten locus coeruleus.

Cells in the locus coeruleus (LC) constitute the sole source of norepinephrine (NE) in the brain and change their discharge rates according to vigilance state. In addition to its well established role in vigilance, NE affects synaptic plasticity in the postnatal critical period (CP) of development. One form of CP synaptic plasticity affected by NE results from monocular occlusion, which leads to physiological and cytoarchitectural alterations in central visual areas. Selective suppression of rapid eye movement sleep (REMS) in the CP kitten enhances the central effects of monocular occlusion. The mechanisms responsible for heightened cortical plasticity following REMS deprivation (REMSD) remain undetermined. One possible mediator of an increase in plasticity is continuous NE outflow, which presumably persists during extended periods of REMSD. Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the synthesis of NE and serves as a marker for NE-producing cells. We selectively suppressed REMS in kittens for 1 week during the CP. The number and size of LC cells expressing immunoreactivity to tyrosine hydroxylase (TH-ir) was assessed in age-matched REMS-deprived (RD)-, treatment-control (TXC)-, and home cage-reared (HCC) animals. Sleep amounts and slow wave activity (SWA) were also examined relative to baseline. Time spent in REMS during the study was lower in RD compared to TXC animals, and RD kittens increased SWA delta power in the latter half of the REMSD period. The estimated total number of TH-ir cells in LC was significantly lower in the RD than in the TXC kittens and numerically lower than in the HCC animals. The size of LC cells expressing TH-ir was greatest in the HCC group. HCC cells were significantly larger than TH-ir cells in the RD kittens. These data are consistent with presumed reduction in NE in forebrain areas, including visual cortex, caused by 1 week of REMSD.

Effect of calorie restriction and refeeding on skin wound healing in the rat.

Calorie restriction (CR) is a reliable anti-aging intervention that attenuates the onset of a number of age-related diseases, reduces oxidative damage, and maintains function during aging. In the current study, we assessed the effects of CR and other feeding regimens on wound healing in 7-month-old Fischer-344 rats from a larger cohort of rats that had been fed either ad libitum (AL) or 40% calorie restricted based on AL consumption. Rats were assigned to one of three diet groups that received three skin punch wounds along the dorsal interscapular region (12-mm diameter near the front limbs) of the back as follows: (1) CR (n = 8) were wounded and maintained on CR until they healed, (2) AL (n = 5) were wounded and maintained on AL until wound closure was completed, and (3) CR rats were refed (RF, n = 9) AL for 48 h prior to wounding and maintained on AL until they healed. We observed that young rats on CR healed more slowly while CR rats refed for 48 h prior to wounding healed as fast as AL fed rats, similar to a study reported in aged CR and RF mice (Reed et al. 1996). Our data suggest that CR subjects, regardless of age, fail to heal well and that provision of increased nutrition to CR subjects prior to wounding enhances the healing process.

Distribution patterns of cannabinoid CB1 receptors in the hippocampus of APPswe/PS1ΔE9 double transgenic mice.

Cannabinoids have neuroprotective effects that are exerted primarily through cannabinoid CB1 receptors in the brain. This study characterized CB1 receptor distribution in the double transgenic (dtg) APP(swe)/PS1(ΔE9) mouse model for Alzheimer's disease. Immunohistochemical labeling of CB1 protein in non-transgenic mice revealed that CB1 was highly expressed in the hippocampus, with the greatest density of CB1 protein observed in the combined hippocampal subregions CA2 and CA3 (CA2/3). CB1 immunoreactivity in the CA1 and CA2/3 hippocampal regions was significantly decreased in the dtg APP(swe)/PS1(ΔE9) mice compared to non-transgenic littermates. Reduced CB1 expression in dtg APP(swe)/PS1(ΔE9) mice was associated with astroglial proliferation and elevated expression of the cytokines inducible nitric oxide synthase and tumor necrosis factor alpha. This finding suggests an anti-inflammatory effect of cannabinoids that is mediated by CB1 receptor, particularly in the CA2/3 region of the hippocampus. Furthermore, the study suggests a decreased CB1 receptor expression may result in diminished anti-inflammatory processes, exacerbating the neuropathology associated with Alzheimer's disease.