Neuropharmacology and analgesia Estradiol increases expression of the brain-derived neurotrophic factor after acute administration of ethanol in the neonatal rat cerebellum Bita Firozan, Iran Goudarzi n , Mahmoud Elahdadi Salmani, Taghi Lashkarbolouki, Arezou Rezaei, Kataneh Abrari School of Biology, Damghan University, Damghan, Iran article info Article history: Received 18 November 2013 Received in revised form 10 February 2014 Accepted 23 February 2014 Available online 18 March 2014 Keywords: Ethanol Purkinje cell 17β-estradiol Neuroprotection Brain derived neurotrophic factor abstract 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 (300–900 μg/kg) was injected subcutaneously in postnatal day (PD) 4, 30 min prior to intraperitoneal injection of ethanol (6 g/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. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Fetal Alcohol Spectrum Disorder (FASD) is associated with persistent deficits in motor coordination and balance that are likely caused, in part, by alterations in the normal trajectory of cerebellar development (Connor et al., 2006; Jacobson et al., 2008; Norman et al., 2009). The cerebellum is one of the brain parts that are strongly influenced during the early postnatal period, a critical period of life (Ben Amara et al., 2009; Nguon et al., 2005). Marcussene and colleagues indicated that rat's expo- sure during differentiation (PD4-9) produced significant reduc- tions in Purkinje cell profile densities, predominantly in the early maturating regions of the vermis (lobules I–IV and IX–XI). These results indicate that Purkinje cells are more venerable to alcohol-induced population depletion during differentiation than during neurogenesis. These sensitive processes may be disturbed by early postnatal ethanol exposure (Marcussen et al., 1994), resulting in massive loss of Purkinje cells, as reported in several studies (Pierce et al., 1999). Previous studies suggested that a number of mechanisms can be underlying ethanol-induced central nervous system (CNS) damage. Among these are (1) alterations in the synthesis or availability of essential neurotrophic factors (NTFs), their receptors, or both; (2) generation of oxidative stress, depletion of protective endogenous antioxidants, or both; and (3) changes in elements of the apoptosis cascade that would compromise neuronal survival (Heaton et al., 2003). It seems that probably these mechanisms together contribute to ethanol-induced damage. There are several reports that NTFs influence the expression and/or stability of protective antioxidant enzymes (Guegan et al., 1999; Mattson et al., 1995; Sampath et al., 1994), whereas NTF levels reduction can induce reactive oxygen species (Fiers et al., 1999; Schulz et al., 1997). Thus, reductions in such neurotrophic support, in addition to depriving developing neuronal populations of substances essential to their maintenance, could also trigger secondary events that would be further damaging. NTFs have also been linked to expression of proteins of the Bcl-2 survival regulatory gene family (Rong et al., 1999) and play a vital role in regulating components of the intrinsic cell death program Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ejphar European Journal of Pharmacology http://dx.doi.org/10.1016/j.ejphar.2014.02.041 0014-2999/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Tel./fax: þ98 232 5247146. E-mail address: irangoudarzi@du.ac.ir (I. Goudarzi). European Journal of Pharmacology 732 (2014) 1–11