Secretion from neuropeptide-treated splenocytes modifies ovarian steroidogenesis

Abstract

There are evidences for modulation of immune function by the sympathetic nervous system and its principal neurotransmitter norepinephrine (NE) through superior ovarian nerve (SON)-coeliac ganglion-noradrenergic postganglionic innervation of the spleen. Seven days after SON transection at 53 days of age, the rat splenocytes were isolated and then cultured for 48 h. These culture media, used to stimulate ovaries from 60-day-old intact rats (neither SON-transected nor sham-operated) at diestrus 2 stage, in in vitro incubations, showed a decrease in progesterone release, an increase in estradiol release and no change in androstenedione release in relation to splenocyte culture media from control (sham-operated) rats. When splenocytes from SON transected (SON-t) rats were treated with vasoactive intestinal peptide (VIP) or neuropeptide Y (NPY), both at 10(-6) M for 24 h, their secretions increased the progesterone release while decreasing the estradiol release from the intact ovaries, compared with the secretions of untreated splenocytes from SON-t rats. Although the secretions of splenocytes treated with VIP decrease the androstenedione release from the ovaries, the treatment with NPY produced no change in hormone release. In the present paper the ovarian steroidogenic response, which was modified by the effects of an in vivo SON transection on spleen cells, was reverted by an in vitro system in which the splenocytes were treated with VIP or NPY. This could indicate that the spleen of SON-t rats does not receive those neuropeptides by neural route however, when they are added to splenocyte culture in vitro, the cell secretions revert the profile of steroid hormones released from the intact ovary. We also present functional evidence for modulation of the immune function by sympathetic nervous system and neurotransmitters other than NE.