Prenatal exposure to sodium valproate alters androgen receptor expression in the developing cerebellum in a region and age specific manner in male and female rats

Abstract

Valproic acid (VPA) is an anti-epileptic drug with teratogenicity activity that has been related to autism. In rodents, exposure to VPA in utero leads to brain abnormalities similar than those reported in the autistic brain. Particularly, VPA reduces the number of Purkinje neurons in the rat cerebellum parallel to cerebellar abnormalities found in autism. Thus, we injected pregnant females on embryonic day 12 either with VPA (600mg/kg, i.p.) or 0.9% saline solution and obtained the cerebellum from their offspring at different postnatal time points. Testosterone has been linked to autism and plays an important role during brain development. Therefore, we identified and analyzed the androgen receptor (AR) by immunohistochemistry and densitometry, respectively. We found VPA decreases AR density in the superficial Purkinje layer only in cerebellar lobule 8 at PN7, but increased it at PN14 compared to control in males. In females, VPA decreased AR density in the superficial Purkinje layer in cerebellar lobule 6 at PN14, but increased it in lobule 9 at the same time point. No differences were found in the deep Purkinje layer of any cerebellar lobule in terms of AR density neither in males nor females. We additionally found a particular AR density decreasing in both superficial and deep regions across development in the majority of cerebellar lobules in males, but in all cerebellar lobules in females. Thus, our results indicate that VPA disrupts the AR ontogeny in the developing cerebellum in an age and region specific manner in male and female rats. Future epigenetic studies including the evaluation of histone deacetylases (HDAC's) might shed light these results as HDAC's are expressed by Purkinje neurons, interact with the AR and are VPA targets. This work contributes to the understanding of the cerebellar development and it might help to understand the role of the cerebellum in neurodevelopmental disorders such as autism.

Pentylenetetrazole-induced seizures in developing rats prenatally exposed to valproic acid

“…It has been proposed that a dysregulation of estrogen receptor signaling may contribute to sex differences in autism (Crider et al, 2014). Interestingly, our work group recently showed that prenatal VPA induces gender-dependent changes in androgen receptor expression in the developing rat cerebellum (Perez-Pouchoulen et al, 2016), which may contribute to explain the differences in seizure susceptibility observed in this study. In the experiments reported by Kim et al (2013), a lower seizure threshold was found after VPA exposure; only male rats were used.…”

Aberrant Development and Synaptic Transmission of Cerebellar Cortex in a VPA Induced Mouse Autism Model

“…Some opinions state that a central inflammatory response is involved, as suggested by microglial activation (Suzuki et al, 2013) and elevated proinflammatory cytokines (Lucchina and Depino, 2014). VPA can also alter the endocannabinoid system (Kerr et al, 2013) or the androgen receptor (Perez-Pouchoulen et al, 2016) in the cerebellum. The neurotrophic factor may form an alternative explanation and we found an elevated expression of the brain derived neurotrophic factor (BDNF) in the P15 cerebellum but no change of its receptor TrkB (Supplementary Figure S5).…”

Sex Differences in Autism Spectrum Disorder: a Review

“…Purkinje cell abnormalities were male-specific in the Reeler mouse model of ASD, and the Adnp mouse model of ASD shows sex-specific hippocampal gene expression, behavior alterations, and response to treatment [224,225]. The VPA mouse model shows complex patterns of sex specificity in androgen receptor expression and deep cerebellar nuclei morphology [226,227]. …”