Melatonin Alleviates Neuronal Damage After Intracerebral Hemorrhage in Hyperglycemic Rats.

BACKGROUND: This study sought to investigate a novel effect of melatonin in reducing brain injury in an in vivo hyperglycemic intracerebral hemorrhage (ICH) model and further explore the mechanisms of protection. METHODS: Hyperglycemia ICH was induced in Sprague-Dawley rats by streptozocin injection followed by autologous blood injection into the striatum. A combined approach including RNA-specific depletion, electron microscopy, magnetic resonance, Western blots, and immunohistological staining was applied to quantify the brain injuries after ICH. RESULTS: Hyperglycemia resulted in enlarged hematoma volume, deteriorated brain edema, and aggravated neuronal mitochondria damage 3 days after ICH. Post-treatment with melatonin 2 hours after ICH dose-dependently improved neurological behavioral performance lasting out to 14 days after ICH. This improved neurological function was associated with enhanced structural and functional integrity of mitochondria. Mechanistic studies revealed that melatonin alleviated mitochondria damage in neurons via activating the PPARδ/PGC-1α pathway. Promisingly, melatonin treatment delayed until 6 hours after ICH still reduced brain edema and improved neurological functions. Melatonin supplementation reduces neuronal damage after hyperglycemic ICH by alleviating mitochondria damage in a PPARδ/PGC-1α-dependent manner. CONCLUSION: Melatonin may represent a therapeutic strategy with a wide therapeutic window to reduce brain damage and improve long-term recovery after ICH.

Exogenous Melatonin for Delirium Prevention: a Meta-analysis of Randomized Controlled Trials.

Recently, two high-quality clinical randomized controlled trials (RCTs) regarding the preventive effect of exogenous melatonin on delirium drew inconsistent conclusions. We therefore performed a systemic review to explore whether melatonin had a benefit on delirium prevention. MEDLINE, EMBASE, and Cochrane Library were searched from January 1980 to April 2015 for English language studies. After strict selection and evaluation, the data were extracted from the included four RCTs. The primary outcome of this meta-analysis was the incidence of delirium. The secondary outcome was the improvement of sleep-wake rhythm. A total of four RCTs with 669 elderly patients were included in the present study. Melatonin group showed a tendency to decrease the incidence of delirium (relative risk [RR] 0.41, 95 % confidence interval [CI] 0.15 to 1.13; P = 0.08) compared with control group. In subgroup analysis of the elderly patients in medical wards, melatonin supplementation decreased the incidence of delirium by 75 % (RR 0.25, 95 % CI 0.07 to 0.88; P = 0.03), but not in sleep-wake disturbance (RR 1.24, 95 % CI 0.51 to 3.00; P = 0.64). No differences were found in the incidence of delirium between the two groups in the elderly patients that were presented to surgical wards. In conclusion, melatonin supplementation had a significant preventive effect in decreasing the incidence of delirium in elderly patients that were presented to medical wards. Further studies should provide sufficient evidence about the effect of melatonin on delirium in a large sample size.

Sex differences in the stress response in SD rats.

Sex differences play an important role in depression, the basis of which is an excessive stress response. We aimed at revealing the neurobiological sex differences in the same study in acute- and chronically-stressed rats. Female Sprague-Dawley (SD) rats were randomly divided into 6 groups: chronic unpredictable mild stress (CUMS), acute foot shock (FS) and controls, animals in all 3 groups were sacrificed in proestrus or diestrus. Male SD rats were randomly divided into 3 groups: CUMS, FS and controls. Comparisons were made of behavioral changes in CUMS and control rats, plasma levels of corticosterone (CORT), testosterone (T) and estradiol (E2), and of the hypothalamic mRNA-expression of stress-related molecules, i.e. estrogen receptor α and ß, androgen receptor, aromatase, mineralocorticoid receptor, glucocorticoid receptor, corticotropin-releasing hormone, arginine vasopressin and oxytocin. CUMS resulted in disordered estrus cycles, more behavioral and hypothalamic stress-related molecules changes and a stronger CORT response in female rats compared with male rats. Female rats also showed decreased E2 and T levels after FS and CUMS, while male FS rats showed increased E2 and male CUMS rats showed decreased T levels. Stress affects the behavioral, endocrine and the molecular response of the stress systems in the hypothalamus of SD rats in a clear sexual dimorphic way, which has parallels in human data on stress and depression.

Effects of curcumin on glucose metabolism in the brains of rats subjected to chronic unpredictable stress: a 18 F-FDG micro-PET study.

BACKGROUND: Chronic unpredictable stress (CUS) can cause behavioral and physiological abnormalities that are important to the prediction of symptoms of depression that may be associated with cerebral glucose metabolic abnormalities. Curcumin showed potential antidepressant effects, but whether or not it can reverse cerebral functional abnormalities and so ameliorate depression remains unknown. METHODS: To investigate the effects of curcumin on brain activity in CUS rats, rats were subjected to 3 weeks of CUS and then treated with curcumin orally at a dose of 40 mg/kg/day for one month. 18 F fluorodeoxyglucose (18 F-FDG)-micro positron emission tomography (micro-PET) neuroimaging was used to detect changes in cerebral metabolism. Body weight, sucrose preference, and open field tests were used to record depressive behaviors during CUS and after curcumin treatment. RESULTS: Three weeks of CUS significantly decreased body weight, sucrose preference, sucrose consumption, total distance travelling, and the number of rearing events. It also induced metabolic alterations in several parts of the brain, showing increased glucose metabolism in the right hemisphere. After curcumin treatment for one month, sucrose preference, sucrose consumption, total distance travelling, and the number of rearing events returned to normal levels. Curcumin treatment also induced strong deactivation of the left primary auditory cortex and activation of amygdalohippocampal cortex. CONCLUSION: Curcumin was found to ameliorate the abnormalities in the behavior and brain glucose metabolism caused by CUS, which may account for its antidepressive effects.