Effects of LHRH-A2 and chlorpromazine (dopamine antagonists) on inducing spawning in Caspian Kutum, Rutilus frisii kutum

Caspian kutum, Rutilus frisii kutum, is one of the most commercially important fish species in the Caspian Sea, but there are few reports about the endocrinology of induced spawning in this fish. In the present study, 54 individuals of female broodstocks of Kutum were studied for quantity and quality of propagation index, during March and April 2007. Hormone treatments include: LHRH-A2 (1? g kg-1bw; chlorpromazine (2.5 mg kg-1bw); LHRH-A2 + chlorpromazine (1?g kg-1bw+2.5 mg kg-1bw); CPE as a positive control (1 mg kg-1bw); Physiological saline as a negative control; and normal brood stocks without injection. For histological examinations, ovarian samples of non-ovulated females were fixed in bouin\''s fluid. The routine procedures of preparation of tissues were followed and the paraffin blocks were cut at 5-7 microns, stained with H&E and studied under light microscope. The results showed that the highest percentage of ovulated females belonged to group 1 without significant difference with positive control. There was a significant difference between ovulated females in the LHRH-A2, chlorpromazine and LHRH-A2 + chlorpromazine treatments (P<0.05), while no significant differences in other propagation indices were found in any of the hormone treatments (P>0.05). Chlorpromazine could not be a potent dopamine antagonist and the microscopic observations of ovary in non- ovulated brood stocks showed that the oocytes in these treatments were in the final phase of IV stage.