Initial studies demonstrated the ability of SP to alter the release of LH after intracerebroventricular or intravenous administration. Although the precise effects caused by the peptide on gonadotrophs have been a subject of controversy for several years, current evidence indicates that SP stimulates LH production both from monolayer cultures of anterior pituitary cells and from perifused pituitary fragments. buy ortho tri-cyclen online
Moreover, in a recent report, Mau et al. have shown SP to increase intracellular Ca2+ in individual pituitary gonadotrophs from rats, thus supporting a direct action of the peptide on this cell type. Nevertheless, there are still a number of aspects of the putative role of SP in gonadotroph control that await consideration. For example, few studies have examined the interaction between SP and the primary hypothalamic factor GnRH in the control of LH release. The absence of information is much more evident in the case of species other than the rat. Thus, the possible influence of SP on LH secretion from porcine gonadotrophs is unknown. Accordingly, the first aim of the present study was to examine the effects of SP on basal and GnRH-induced LH release in cell monolayers from immature female pig pituitaries. Furthermore, in an attempt to ascertain the action kinetics of both peptides on LH secretion, we employed a superfusion system to evaluate the response of pig pituitary fragments to SP and/or GnRH treatment.