Estradiol increases expression of the brain-derived neurotrophic factor after acute administration of ethanol in the neonatal rat cerebellum.

Recently it has been shown that estradiol prevents the toxicity of ethanol in developing cerebellum. The neuroprotective effect of estradiol is not due to a single phenomenon but rather encompasses a spectrum of independent proccesses. According to the specific timing of Purkinje cell vulnerability to ethanol and several protective mechanisms of estradiol, we considered the neurotrophin system, as a regulator of differentiation, maturation and survival of neurons during CNS development. Interactions between estrogen and Brain derived neurotrophic factor (BDNF, an essential factor in neuronal survival) lead us to investigate involvement of BDNF pathway in neuroprotective effects of estrogen against ethanol toxicity. In this study, 17β-estradiol (300-900μg/kg) was injected subcutaneously in postnatal day (PD) 4, 30min prior to intraperitoneal injection of ethanol (6g/kg) in rat pups. Eight hours after injection of ethanol, BDNF mRNA and protein levels were assayed. Behavioral studies, including rotarod and locomotor activity tests were performed in PD 21-23 and histological study was performed after completion of behavioral tests in PD 23. Our results indicated that estradiol increased BDNF mRNA and protein levels in the presence of ethanol. We also observed that pretreatment with estradiol significantly attenuated ethanol-induced motoric impairment. Histological analysis also demonstrated that estradiol prevented Purkinje cell loss following ethanol treatment. These results provide evidence on the possible mechanisms of estradiol neuroprotection against ethanol toxicity.