Concentrations of Catecholamines in the Median Eminence of Sheep after Superovulation

Abstract

Pástorová B.: Concentrations of Catecholamines in the Median Eminence of the sheep after superovulation. Acta vet. Brno 2008, 77:159-162 the effect of hormonal superovulation preparations of FsH (450 IU) or PMsG (1500 IU), on concentration of catecholamines (dopamine, norepinephrine and epinephrine) was studied in the oestrus period using radioenzymatic methods in the median eminence of the sheep.The administration of FSH caused a significant increase in the concentrations of norepinephrine (NE) and epinephrine (EPI) in the median eminence (ME) of sheep (p < 0.01 and p < 0.05, respectively). the comparison of the effect of hormonal preparations on the changes in catecholamine levels showed that the effect of FsH was observed mostly in eminentia mediana of sheep.We propose that the given changes in concentrations of catecholamines in the median eminence of sheep after administration of PMsG or FsH are related to steroids after hormonal stimulation. Ewes, brain, norepinephrine, dopamine, FSH and PMSG superovulationthe median eminence (ME) represents a small mildly convex protuberance situated in front of and behind the infundibulum (Rajtová and Kačmárik 1999); it forms the floor of the third ventricle. This site has more morphological features; numerous nerve pathways converge here and biologically active compounds and neurotransmitters accumulate. the ME is also considered as the terminal field where higher numbers of neurons from different cerebral regions terminate. the hormonal preparations generally used for inducing superovulation in farm animals act on steroidogenesis and influence hypothalamic nuclei and their gonadotropic receptors through a feedback mechanism (Deaver and Dailey 1983). High concentrations of circulating oestrogens affect adrenergic receptors and the levels and metabolism of catecholamines in the central and peripheral adrenergic system (FernandezPardal et al. 1986; Pástorová and Várady 1996ab). Simultaneously with changes in the metabolism of catecholamines, some changes in the activity of catecholamine-degrading enzymes in brain of sheep were observed after hormonal treatment (Chevillard et al. 1981;Pástorová and Várady 1996a). With regard to the sporadic information about the effect of hormonal preparations that are commonly used in the biotechnology of controlled reproduction on the catecholaminergic system in the median eminence of sheep, we studied changes in catecholamines after administration of FsH and PMsG. Materials and MethodsExaminations were carried out using brain samples from 18 slovak Merino sheep, 2 -3 years old, of average body mass 42 ± 3.8 kg, in their oestrous period (september -october). the sheep were fed standard molasses feed with vitamin additives twice daily. the oestrus of all sheep was synchronized with intravaginal sponges (20 mg chlorsuperlutin). on day 13 after instillation, the sponges were removed and FsH ad usum vet. (FolIstIMAN, spofa, Prague) was administered i.m. to the first experimental group (n = 6) three times daily for 2 days at total ...