LAUSR

Effects of salmon gonadotropin releasing hormone analogue (sGnRH-A) and antidopaminergic drug, pimozide, on the synthesis of prolactin mRNA in vivo in female Prussian carp ( Carassius gibelio Bloch) during two different stages of the reproductive cycle were evaluated. The results showed that the lowest dose of sGnRH-A (5 μg/kg body weight) significantly stimulated the mRNA synthesis in fish during the recrudes - cence as well as during the preovulatory period, higher doses of this compound having no significant effect on prolactin mRNA synthesis. The blocker of dopamine receptors, pimozide, also potentiated prolactin mRNA synthesis - in recrudescent females it increased mRNA levels at the dose of 1 mg/kg, while in the preovula - tory period all of the used pimozide doses (1, 5, and 10 mg/kg) were responsible for the increase of prolactin mRNA levels. Taken together, the above results suggest that gonadotropin releasing hormone (GnRH) is the factor responsible for the stimulation of prolactin synthesis, while dopamine has an inhibitory influence on the prolactin production.