Acting at the level of the brain, interleukin- (IL-)1βis considered to be one of the most potent downregulators of reproduction processes during immune/inflammatory challenge. IL-1βsuppresses gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus resulting in the inhibition of the luteinizing hormone (LH) release from the anterior pituitary (AP). However, the presence of IL-1βreceptors in the AP suggests the possible direct action of this cytokine on LH secretion. The study was designed to determine the effect of IL-1βon the LH secretion from the AP explants collected from saline and LPS-treated ewes in the follicular phase. It was found that IL-1βsuppressed () GnRH-stimulated LH release and LHβgene expression in AP explants in both groups. However, IL-1βaction was more potent in the explants collected from LPS-treated animals. Pituitaries from LPS-treated animals were characterized by increased () IL-1 type I receptor and decreased () GnRH receptor gene expression level compared to the saline-treated group. IL-1βalso affected the GnRH-R gene expression in explants collected from LPS-treated animals. Our results show that direct action of IL-1βon the pituitary gonadotropes could be one of the reasons of the reproductive processes disorders accompanying an inflammatory state.

The push–pull perfusions of the infundibular nucleus–median eminence (IN/ME) were made in lactating ewes (n=7) twice, to identify dopamine (DA)-derived salsolinol and the changes in its extracellular concentration in response to suckling. The perfusate collecting period in every ewe consisted of control non-suckling period, 1000–1230 h (five perfusates), and suckling period, 1230–1500 h (next five perfusates). Simultaneously, blood samples were collected from 1000 to 1500 h at 10-min intervals. The perfusate concentrations of salsolinol and DA were measured by HPLC, and plasma prolactin and GH concentrations were assayed by the RIA. Mean concentrations of salsolinol in perfusates collected from the anterior and posterior parts of the IN/ME (according to post-mortem localization of a perfusion site) increased significantly (P<0.05 and P<0.001 respectively) during the suckling period, when compared with those noted during the non-suckling period. While no DA was found in the anterior part, only vestigial amounts of DA were found in a few perfusates collected from the posterior part. Salsolinol was not detected in the IN/ME of ewes 10 weeks after weaning (seasonal anoestrus). Mean plasma prolactin and GH concentrations during suckling were significantly (P<0.001) higher than those noted during the non-suckling period. In conclusion, our current study reveals that salsolinol is present in the IN/ME of lactating ewes and that its extracellular concentration increases during suckling. Moreover, it supports the role of salsolinol as a neurotransmitter involved in the regulatory process of prolactin secretion at least during lactation.