The therapeutic potential of 1, 25-dihydroxy vitamin D3 on cisplatin-affected neurological functions is associated with the regulation of oxidative stress and inflammatory markers as well as levels of MMP2/9.

Calcitriol as a biologically active form of vitamin D3 has beneficial effects on all body systems. This vitamin has a potent neuroprotective effect via several independent mechanisms against brain insults induced by anticancer drugs. The present study was designed to examine the neuroprotective effects of calcitriol against neurotoxicity induced by cisplatin. Induction of neurotoxicity was done with cisplatin administration (5 mg/kg/week) for 5 successive weeks in male Wistar rats. The neuroprotective influence of calcitriol supplementation (100ng/kg/day for 5 weeks) was assessed through behavioral, electrophysiological, and molecular experiments. Cisplatin administration impaired spatial learning and memory and decreased prefrontal brain-derived neurotrophic factor (BDNF). Peripheral sensory neuropathy was induced through cisplatin administration. Cisplatin also reduced the amplitudes of the compound action potential of sensory nerves in electrophysiological studies. Cisplatin treatment elevated MDA levels and reduced anti-oxidant (SOD and GPx) enzymes. Pro-inflammatory cytokines (IL-1ß and TNF-α) and metalloproteinase-2 and 9 (MMP-2/9) were augmented through treatment with cisplatin. Learning and memory impairments along with BDNF changes caused by cisplatin were amended with calcitriol supplementation. Reduced sensory nerve conduction velocity in the cisplatin-treated group was improved by calcitriol. Calcitriol partially improved redox imbalance and diminished the pro-inflammatory cytokines and MMP-2/9 levels. Our findings showed that calcitriol supplementation can relieve cisplatin-induced peripheral neurotoxicity. Calcitriol can be regarded as a promising new neuroprotective agent.

Beneficial effects of enriched environment on behavior, cognitive functions, and hippocampal brain-derived neurotrophic factor level following postnatal serotonin depletion in male rats.

The neurotransmitter serotonin (5-HT) is one of the most important modulators of neural circuitry and has a critical role in neural development and functions. Previous studies indicated that changes in serotonergic system signaling in early life critically impact mental health, behavior, the morphology of hippocampal neurons, and cognitive functions across the lifespan. The enriched environment (EE) has indicated beneficial effects on behavior and cognitive functions in the developmental period of life, but its impacts on cognitive impairments and behavioral changes following postnatal serotonin depletion are unknown. Therefore, the present study aimed to evaluate the influences of the EE housing (postnatal days [PNDs] 21-60) following postnatal serotonin depletion (by para-chlorophenylalanine [PCPA], 100 mg/kg, s.c, in PNDs 10-20) on anxiety-related behaviors, cognitive functions, and brain-derived neurotrophic factor (BDNF) mRNA expression in the hippocampus of male rats. Memory and behavioral parameters were examined in early adulthood and after that, the hippocampi of rats were removed to determine the BDNF mRNA expression by PCR (PNDs 60-70). The findings of the present work indicated that adolescent EE exposure alleviated memory impairment, decreased BDNF levels, and anxiety disorders induced by experimental depletion of serotonin. Overall, these results indicate that serotonergic system dysregulation during the developmental periods can be alleviated by adolescent EE exposure.

Calcitriol supplementation attenuates cisplatin-induced behavioral and cognitive impairments through up-regulation of BDNF in male rats.

Chemotherapy-induced cognitive impairment such as memory impairment and concentration problems are now extensively recognized as side effects of chemotherapy. These problems reduce the quality of life in patients. Therefore, the present study aims to examine the effects of calcitriol supplementation (100 ng/kg /day for five weeks) on cognitive impairment, behavioral deficits, and hippocampal brain-derived neurotrophic factor (BDNF) changes following cisplatin treatment (5 mg/kg/ once a week for five weeks). We also determined the impact of cisplatin and calcitriol administration on reaction time against the thermal stimulus and muscle strength. Our findings showed that cisplatin administration resulted in a significant increase in anxiety-like behaviors. Treatment of rats with cisplatin also impaired performance in the passive avoidance and novel object recognition tasks which are indicating cognitive deficits. Co-administration of calcitriol prevented the cisplatin-induced behavioral and cognitive impairments. Cisplatin exposure also resulted in enhanced reaction time to the thermal stimulus and decreased muscle ability. Besides, hippocampal BDNF levels were reduced in cisplatin-treated rats; however, calcitriol alleviated these effects of cisplatin and up-regulated BDNF mRNA in the hippocampus. In addition, calcitriol alone indicated a significant change in BDNF level compared to the control group. We conclude that increased hippocampal BDNF mediates the beneficial effects of calcitriol against neurotoxicity in cisplatin-exposed rats. However, further studies are required to explore the other mechanisms that mediate the beneficial effect of calcitriol.

Adolescent enriched environment exposure alleviates cognitive impairments in sleep-deprived male rats: Role of hippocampal brain-derived neurotrophic factor.

Developmental life experience has long-lasting influences on the brain and behavior. The present study aims to examine the long-term effects of the enriched environment (EE), which was imposed during the adolescence period of life, on their passive avoidance and recognition memories as well as anxiety-like behaviors and hippocampal brain-derived neurotrophic factor (BDNF) levels, in sleep-deprived male rats. In the present study, the male pups were separated from their mothers in postnatal day 21 (PND21) and were housed in the standard or EE for 40 days. In PND 61, the rats were allocated in four groups: control, SD (sleep deprivation), EE, and EE + SD groups. SD was induced in rats by a modified multiple platform model for 24 h. Open field, novel object recognition memory, and passive avoidance memory tests were used to examine behavior and cognitive ability. The expression of hippocampal BDNF levels was determined by PCR. The results revealed that SD increased anxiety-like behaviors and impaired cognitive ability, while adolescent EE housing alleviated these changes. In addition, EE reversed SD-induced changes in hippocampal BDNF level. We also demonstrated that EE not only has beneficial effects on the cognitive functions of normal rats but also declined memory deficits induced by SD. In conclusion, our results suggest that housing in EE during the adolescence period of life reduces cognitive impairment induced by SD. The increase of the BDNF level in the hippocampus is a possible mechanism to alleviate cognitive performance in sleep-deprived rats.