It is known that the brain is able to synthesize several biologically active neurosteroids including 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone and androstenedione.

We investigated the immunohistochemical localization and molecular expression of the cytochrome P450 17a-hydroxylase/C17, 20-lyase (P450C17), an enzyme which plays a pivotal role in the synthesis of these hormones from pregnenolone and progesterone. The study has been performed in vestibular and cerebellar nuclei of adult male rats to evaluate the neurosteroids involvement in vestibular and cerebellar functions. P450C17 was detected by indirect immunofluorescence and Western Blot analysis in Superior, Lateral, Medial and Inferior vestibular nuclei as well as in Dentatus, Interpositum and Fastigii cerebellar nuclei. Results showed that P450C17 immunoreactivity was widely distributed in vestibular and cerebellar nuclei. The expression of P450C17 in these structures was also confirmed by Western Blot analysis. These findings are in agreement with earlier studies performed on rat brain slices showing that several neurosteroids are responsible for long term potentiation of medial vestibular neurons. Moreover, results show for the first time that P450C17 is expressed in cerebellar nuclei. Since vestibular and cerebellar nuclei are involved in postural and motion control, it could be assumed that neurosteroids from P450C17 influence this complex function of the central nervous system.