Neuroscience
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Sex differences in neural structures are generally believed to underlie sex differences reported in anxiety, depression, and the hypothalamic-pituitary-adrenal axis, although the specific circuitry involved is largely unclear. Using a corticotropin-releasing factor receptor 1 (CRFR1) reporter mouse line, we report a sexually dimorphic distribution of CRFR1 expressing cells within the paraventricular hypothalamus (PVN; males > females). Relative to adult levels, PVN CRFR1-expressing cells are sparse and not sexually dimorphic at postnatal days 0, 4, or 21. ⋯ CRFR1 cells show moderate co-expression with estrogen receptor alpha (ERα) and high co-expression with androgen receptor, indicating potential mechanisms through which circulating gonadal hormones might regulate CRFR1 expression and function. Finally, we demonstrate that a psychological stressor, restraint stress, induces a sexually dimorphic pattern of neural activation in PVN CRFR1 cells (males >females) as assessed by co-localization with the transcription/neural activation marker phosphorylated CREB. Given the known role of CRFR1 in regulating stress-associated behaviors and hormonal responses, this CRFR1 PVN sex difference might contribute to sex differences in these functions.
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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by selective loss of motor neurons. Statins are widely used as cholesterol-lowering drugs and significantly reduce the risk of cardiovascular and cerebrovascular diseases. Increasing evidence indicates the protective effects of statins against certain neurodegenerative diseases. ⋯ Conversely, these outcomes were completely reversed by co-incubation with mevalonate, farnesyl pyrophosphate (FPP) or geranylgeranyl pyrophosphate (GGPP) but not cholesterol. In addition, inhibition of geranylgeranyl transferase I by GGTI-286 led to similar alterations in cell viability and autophagic marker levels. These results indicated that the cytotoxic effect of simvastatin on NSC34-hSOD1G93A cells might be due to the aggravation of autophagic flux impairment through the inhibition of GGPP synthesis.
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Stress is a non-specific, systemic, physiological response of the body to strong internal and external environmental stimuli. Accumulating evidence has suggested that stress, particularly chronic restraint stress (CRS), can reduce pain threshold and increase pain sensitivity. However, pathogenic and therapeutic mechanisms underlying CRS remain unclear. ⋯ Notably, only the intrathecal injection improved PWMT and TFL. Additionally, an intraperitoneal injection of rapamycin, an mTOR inhibitor, failed to induce any behavioral changes, whereas a single intrathecal injection of rapamycin improved abnormal CRS-induced PWMT and TFL. In conclusion, CRS can induce abnormal pain sensitivity, probably by altering the BDNF-mTOR signaling pathway in the spinal cord.
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Benzodiazepines are one of the most commonly prescribed anxiolytic drugs in America, and between 2006 and 2015 prescription rates increased by an estimated 27.1%. Weight gain is a common side effect of these drugs and it may result from increased feeding caused by drug-enhanced food palatability. We investigated the role of specific GABAA receptor subtypes involved with benzodiazepine-induced food consumption through third ventricle injections of L-838,417, a partial agonist of GABAA α2, α3, and α5 subunits, and a full antagonist of the α1 receptor subunit. ⋯ These results indicate that nuclei in proximity to the ventricles respond to GABAA α2, α3, or α5 activation to induce motivation to feed, absent of α1 receptor subunit activation. Furthermore, activation of the α1 subunit is not necessary for benzodiazepine hyperphagia and may instead contribute to the oromotor depressant and sedative properties of classic benzodiazepine agonists. Hypothalamic nuclei such as the paraventricular nucleus may be involved in the benzodiazepine-increased motivation to feed, while the parabrachial nucleus of the hindbrain could contribute to benzodiazepine-induced enhancement of taste palatability.
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Estrogen receptor-alpha (ERα) and -beta (ERβ) 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 ERβ 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. ⋯ 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 -β. 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.