Premium
Substance P and neurokinin A variations throughout the rat estrous cycle; comparison with ovariectomized and male rats: I. Plasma, hypothalamus, anterior and posterior pituitary
Author(s) -
Duval Pierre,
Lenoir Véronique,
Moussaoui Saliha,
Garret Claude,
Kerdelhué Bernard
Publication year - 1996
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19960901)45:5<598::aid-jnr9>3.0.co;2-7
Subject(s) - ovariectomized rat , medicine , endocrinology , neurokinin a , estrous cycle , substance p , neurokinin b , hypothalamus , anterior pituitary , chemistry , neuropeptide , biology , hormone , receptor
The concentrations of Substance P and Neurokinin A were measured in plasma, and the hypothalamo‐pituitary complex of 4‐day‐cycling female, ovariectomized and male rats. Estrous cycle‐related fluctuations were recorded for these two neurokinins. The patterns of plasma concentrations of Substance P and Neurokinin A, however, were not similar throughout the rat estrous cycle. The plasma concentration of Substance P increased on proestrus at 19.00 hr, while Neurokinin A decreased. The plasma concentration of Substance P was positively correlated with plasma 17β‐estradiol levels. In the ovariectomized rat, the absence of ovarian steroids led to low levels of plasma Neurokinin A, but the plasma concentration of Substance P did not show any change as compared to the estrous cycle. In the male rat, a similar observation was made in the presence of a testosterone environment. The largest variations in tissue concentration of both peptides were observed in the anterior pituitary. Substance P and Neurokinin A contents were higher throughout the proestrous day than the 3 other days. However, the level fell at 18.00 hr on proestrus, and there were similar falls in the hypothalamic contents of Substance P and Neurokinin A at 19.00 hr. In the ovariectomized rat, with no gonadal steroids, the hypothalamic and/or anterior pituitary levels of Substance P were in the same range as during the estrous cycle. However, the hypothalamic levels of Neurokinin A were lower and Neurokinin A was undetectable in the anterior pituitary. Substance P and Neurokinin A concentrations in the posterior pituitary were stable throughout the estrous cycle, with the exception of rises for both peptides on estrous day. Substance P levels were much lower in ovariectomized and male rats. These results describe large fluctuations in hypothalamic and pituitary Substance P and Neurokinin A contents through the estrous cycle in the female rat. They also strongly suggest the involvement of gonadal steroids in the differential regulation of Substance P and Neurokinin A in the female and male rat. © 1996 Wiley‐Liss, Inc.