The influence of PMSG and antisergon on monoamine oxidase activity in some hypothalamic-hypophysiary structures and in the epiphysis of sheep in the estrus period

Abstract

Hormonal influence resulting from serum gonadotropin was investigated by radiochemical activity studies of the degradation enzyme of monoamine oxidase catecholamines (MAO) in certain regions of the hypothalamus (area preoptica, corpus mamillare, infundibulum), which participates in the regulation of sheep sexual functioning, as well as in nucleus caudatus, in the hypophysis and epiphysis. We attempted to eliminate the negative effect of PMSG by application of anti-PMSG serum (Antisergon) administered 24 and 58 hours after PMSG. The administration of 100 IU PMSG resulted in statistically significant (p < 0.01) increases in MAO activity (by 25.9%) in the area preoptica of the hypothalamus of sheep, in comparison to a control group with synchronized estrus. After the administration of Antisergon (after 58 hours) this increase was adjusted to the level of MAO activity of the control group. The most pronounced increase in MAO activity (by 82.8%) was recorded in infundibulum. After the administration of AntiPMSG, 24 and 58 hours post PMSG, MAO activity in infundibulum did not differ from that of the control group. MAO activity in the hypophysis and epiphysis of sheep after administration of PMSG, showed a significant decrease (p < 0.01), persisting even after administration of Antisergon. Our results indicate that hormonal stimulation with serum gonadotropin causes an increase in MAO activity in the observed regions of sheep hypothalamus. The changes are less pronounced after administration of Antisergon. Hypophysis and epiphysis react to the hormonal preparation by a decrease in MAO activity which persists even after administration of anti-PMSG serum.