Immunocytochemical Evidence that Suckling Inhibits the Postovariectomy Depletion of Median Eminence Luteinizing Hormone Releasing Hormone
- 1 January 1982
- journal article
- research article
- Published by S. Karger AG in Neuroendocrinology
- Vol. 34 (4), 258-264
- https://doi.org/10.1159/000123309
Abstract
Suckling has been demonstrated to impair the release of pituitary luteinizing hormone (LH) and to prevent the dramatic increase in plasma LH observed following ovariectomy. In the present study, the effect of suckling (10 pups/animal) for either 1 or 3 weeks on the relative amount of luteinizing hormone releasing hormone (LHRH) present in the hypothalamus and preoptic area of ovariectomized and intact rats was examined using immunocytochemical methodology. Controls consisted of nonlactating animals which were either intact (diestrous) or ovariectomized for 1 or 3 weeks. Brains were removed following transcardial perfusion of phosphate-buffered formalin and Bouin’s fixative. After dehydration, clearing and paraffin embedding, the brains were sectioned and LHRH localized by an indirect immunoperoxidase technique. A positive reaction denoting the presence of immunoreactive LHRH was observed over axons and termini throughout the rostral to caudal extent of the median eminence (ME) and surrounding the organum vasculosum of the lamina terminalis (OVLT) in the preoptic area. Ovariectomy resulted in a progressive decline in the concentration of LHRH within the ME as evidenced by a reduction in the intensity of the staining reaction and in the number of axons over which the reaction was observed. In contrast, brains from ovariectomized rats which had been suckled appeared to have concentrations of LHRH in the ME equal to or greater than that of the diestrous controls. Similarly, the concentration of LHRH In the ME of intact, suckled rats did not differ significantly from that of the diestrous controls. Neither ovariectomy nor suckling produced any observable change in the relative concentration of LHRH located near the OVLT. These data demonstrate that suckling prevents the depletion of LHRH from the ME following ovariectomy and provide evidence for mechanism by which the suckling stimulus may suppress plasma LH.This publication has 16 references indexed in Scilit:
- Effect of Ovariectomy and Adrenalectomy on Luteinizing Hormone-Releasing Hormone in Pituitary Stalk Blood from Female Rats*Endocrinology, 1980
- I mmunohistochemistry of Hypothalamic GN RH Following Manipulation of Sex Steroid Levels: Evidence that Androgens have Divergent Effects on GNRH Stores and Serum Follicle Stimulating Hormone Levels1, 2Biology of Reproduction, 1978
- A Comparison of Pituitary Responsiveness to Luteinizing Hormone-Releasing Hormone during Lactation and the Estrous Cycle of the Rat*Endocrinology, 1978
- Regional Distribution of Hypothalamic Luteinizing Hormone-Releasing Hormone in Proestrous Rats: Effects of Ovariectomy and Estrogen Replacement*Endocrinology, 1978
- Effects of Castration, Steroid Replacement, and Hypophysectomy on Hypothalamic LHRH and Serum LHExperimental Biology and Medicine, 1977
- Inhibition of Gonadotropin Secretion During Lactation in the Rat: Relative Contribution of Suckling and Ovarian Steroids1Biology of Reproduction, 1977
- Higher molecular weight immunoreactive species of luteinizing hormone releasing hormone: Possible precursors of the hormoneBiochemical and Biophysical Research Communications, 1977
- Pituitary Stalk Portal Blood Collection in Rhesus Monkeys: Evidence for Pulsatile Release of Gonadotropin-Releasing Hormone (GnRH)Endocrinology, 1976
- Luteinizing Hormone-Releasing Hormone in Peripheral Plasma and Hypothalamus of Normal and Ovariectomized RatsNeuroendocrinology, 1976
- Effects of Suckling on Hypothalamic LH-Releasing Factor and Prolactin Inhibiting Factor, and on Pituitary LH and ProlactinEndocrinology, 1967