Induction of ovulation in the loach (Paramisgurnus dabryanus) using pimozide and [D-Ala6, Pro9-N-ethylamide]-LHRH

The effects of intraperitoneal injections of [D-Ala6, Pro9-N-ethylaminde]-luteinizing hormone releasing hormone (LHRH-A) and pimozide (PIM), a dopamine receptor antagonist, on ovulation in loach were investigated. LHRH-A and PIM administered separately were ineffective in inducing ovulation. However, injections of PIM and LHRH-A simultaneously or the injection of PIM 2.5–3 h prior to LHRH-A were highly effective means of inducing ovulation. The simultaneous injection of PIM (1.0 μg/g body wt) and LHRH-A (0.05 μg/g body wt) resulted in a greater ovulatory response than injection of carp pituitary extract (1 pituitary/fish).