Specific neural phase relation of serotonin and dopamine modulate the testicular activity in Japanese quail.

Specific phase relation of serotonin and dopamine modulate the hypothalamo-hypophyseal-gonadal axis as well as photosexual responses in Japanese quail， but the effect of these specific phase relations on testicular activity and steroidogenesis is not yet been investigated. We hypothesized that temporal phase relation induced alteration in local testicular gonadotropin-releasing hormone (GnRH)-Gonadotropin-inhibitory hormone (GnIH) and their receptor system may modulate the testicular activity and steroidogenesis through local (paracrine and autocrine) action. To validate this hypothesis， we have checked the alterations in the expression of gonadotropin-releasing hormone receptor (GnRH-R)， gonadotropin-inhibitory hormone receptor (GnIH-R) messenger RNA (mRNA)， growth hormone receptor (GH-R)， proliferating cell nuclear antigen (PCNA)， cell communication and gap junctional proteins (14-3-3 and connexin-43 [Cnx-43])， steroidogenic factor-1 (SF-1)， steroidogenic acute regulatory (StAR) protein， steroidogenic enzyme (3β-hydroxysteroid dehydrogenase [3β-HSD]) in testis as well as androgen receptor (AR) in testis and epididymis of control， 8-， and 12-hr quail. Experimental findings clearly indicate the increased expression of GnIH-R mRNA and suppression of GnRH-R， GH-R， PCNA， 14-3-3， Cnx-43， SF-1， StAR， 3β-HSD in testis as well as AR in testis and epididymis in 8-hr quail， while 12-hr quail exhibited the opposite results that is significantly decreased expression of GnIH-R mRNA and increased expression of GnRH-R， GH-R， PCNA， 14-3-3， Cnx-43， SF-1， StAR， 3β-HSD in testis as well as AR in testis and epididymis. The significantly increased intratesticular testosterone has been observed in the 12-hr quail while， 8-hr quail showed opposite result. Hence， it can be concluded that 12-hr quail showed significantly increased testicular activity and steroidogenesis while opposite pattern was observed in 8-hr quail.