Ovulation and spawning induction in Rutilus frisii kutum: Advances in application of catecholaminergic pharmaceutics at different doses as compared with ovaprim a potent ovulating agent

The involvement of adrenergic and dopaminergic receptor subunits are recognized in regulating fish repoduction. The potential for neuroendocrine novel pharmaceutics to induce final maturation and ovulation has not been well studied. The aim of the present study was to investigate the effects of new catecholamine pharmaceutics at different doses, including clozapine and olanzapine (the third generation of D4 and D2 dopamine receptor antagonists, respectively), which could be more effective than the first and second generations, salbutamol (β2-adrenergic receptor agonist) and metoprolol (β1- adrenergic receptor antagonist) as compared with ovaprim (D-Ala6,Pro9-Net)-sGnRH+Domperidone, on final oocyte maturation (FOM), ovulation and spawning in Rutilus frisii kutum. In the present investigation, 126 gravid females were injected once with ovaprim, 0.5mlkg-1 BW, salbutamol sulphate (SLB) 2, 4 or 8 mg kg-1 BW; metoprolol tartrate (MTP) 5, 10 or 20 mg kg-1 BW; olanzapine (OLZ) 2, 5 or 10 mg kg-1 BW; clozapine (CZ) 2, 8 or 12 mg kg-1 BW (N=9), been divided into 14 groups. Intact and ovaprim were negative and positive Control groups respectively. The results showed that all fish dosed with 0.5 ml kg-1 of ovaprim ovulated within 13 hours after injection,while no fish ovulated in negative control group (Intact). The parameters include ovulation index, fertilization success, relative fecundity and the number of eggs which were the highest mean values belonged to ovaprim treatment. Ovulation succes (100%) was obtained in OLZ 5 mg kg-1, CZ 12 mg kg-1, MTP 5 mg kg-1 and SLB 4 mg kg-1 treatments. Therefore, it could be concluded that SLB 4 mg appears to employ β2-adrenoceptor mechanisms in mediating the considered effects. In contrast, MTP at high doses (10 mg and 20 mg) significantly inhibited the stimulatory effect of adrenergic system on FOM and ovulation. The stimulation by the blocker (MTP) was higher in the low dose, 5 mg kg-1. The successful spawning using CZ 12 mg and OLZ 5 mg are important steps in the expansion of the culture of Caspian kutum.