Vitamin D receptor expression and acid sphingomyelinase activity in prefrontal region of a learning animal model.

Contextual fear conditioning (CFC) paradigm is routinely used to study fear-based learning in animals and it provides a useful model for understanding fear and anxiety in human. In the present study, such model was used following the previously established CFC protocol, and immunohistochemistry, enzymatic activity and western blotting analysis approaches were used to identify the expression of acid sphingomyelinase (aSMase) and vitamin D receptor (VDR) in prefrontal region brain of rat. Results revealed an increase of aSMase activity in conditioned rats, suggesting an apoptotic condition in such animals. In addition, an increase of density and organization of axonal neurofilaments and of VDR expression has been observed in brain of conditioned rats, supporting an induction of growth and organization of new neurons in prefrontal regions, whose contribution to various aspects of contextual fear learning is still largely unknown.