Serotonin, GnRH-A, and dopamine interaction in the control of in vivo luteinizing hormone release in Prussian carp (Carassius gibelio Bloch) at the time of gonad recrudescence

Abstract

The effects of serotonin (5-HT), GnRH analogue (D-Ala6 LHRH, GnRH-A) and dopamine antagonist - pimozide (PIM), on luteinizing hormone (LH) release in mature Prussian carp female (Carassius gibelio Bloch) were examined at the time of gonad recrudescence. Fish were intraperitoneally injected with 5-HT (10 mg/kg), GnRH-A (20 μg/kg) or PIM (5 mg/kg) or the combinations: 5-HT+GnRH-A, 5-HT+PIM, 5-HT+GnRH-A+PIM. Before the injection and 3, 6, 12 or 24 h after treatment blood samples were collected for LH levels determination by ELISA method. The analysis of LH concentrations, expressed as the percentage of pre-treatment, showed that serotonin alone had no influence on the spontaneous LH release, however the additive effects of serotonin and GnRH-A was observed. Serotonin potentiated the GnRH-A-stimulated LH release and potentiated also the effect of PIM. Extremely strong response to PIM and also to the combination with GnRH-A masked the participation of serotonin in the process of LH release in fish with recrudescing gonads. The interaction of serotonin GnRH-A and PIM in the control of LH release is discussed.

Keywords

• gonadotropin-releasing hormone analoque
• lh
• pimozide - dopamine antagonist
• serotonin