Dynamic expression of 11β-hydroxylase during testicular development, recrudescence and after hCG induction, in vivo and in vitro in catfish, Clarias batrachus

•Dimorphic expression of 11β-hydroxylase (11β-h) during gonadal ontogeny in catfish.•Multiple forms of 11β-h with differential expression in various tissues.•Differential expression of 11β-h and 11-KT levels during gonadal recrudescence.•Expression of 11β-h was upregulated after hCG induction.•11β-h localization in Sertoli cells in addition to interstitial/Leydig cells.

Cytochrome P450 11β-hydroxylase (11β-h), is involved in the production of 11-hydroxytestosterone, an immediate precursor for 11-ketotestosterone (11-KT), a potent androgen in teleosts. To understand the role of 11β-h in gonadal development, maturation, function and recrudescence in an annually reproducing teleost, the present study was conducted using Clarias batrachus. Four forms of 11β-h cDNA, regular type (2.253 kb), variant 1 (1.290 kb), variant 2 (1.223 kb) and variant 3 (1.978 kb) were identified from the testis of catfish which expressed ubiquitously with high levels in testis. 11β-h transcripts were detected as early as 0 days post hatch further, stage- and sex-dependent increase in the 11β-h transcripts were seen during gonadal differentiation/development. In addition, high expression of 11β-h (regular type) in pre-spawning phase was detected. Corroboratively, levels of 11-KT in serum and testicular tissue was high during pre-spawning and spawning phases, which might facilitate initiation and normal progression of spermatogenesis. The expression of 11β-h was high after human chorionic gonadotropin induction in vivo (all forms), and in vitro (regular type). Immunohistochemical and immunofluorescence localization showed the presence of 11β-h in Sertoli and interstitial/Leydig cells of the testis. These results suggest that 11β-h is involved in late stages of testicular development, together with the regulation of seasonal reproductive cycle in catfish.