Effects of lesions in the medial basal part of the suprachiasmatic area on prolactin and gonadotropin surges induced by estrogen and progesterone treatment in ovariectomized rats

Kawakami, M.; Arita, J.

Neuroendocrinology 32(4): 242-247


ISSN/ISBN: 0028-3835
PMID: 6783974
DOI: 10.1159/000123166
Accession: 000874686

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Bilateral lesions in the medial basal part of the suprachiasmatic area (MBSC) lying immediately rostral to the suprachiasmatic nuclei caused persistent vaginal cornification. Estradiol benzoate (EB) injections induced a surge in serum prolactin, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels between 15.00 and 18.00 h in ovariectomized rats bearing sham lesions in the MBSC. The EB-induced surge of LH and FSH release was eliminated in ovariectomized animals with lesions in the MBSC. Serum prolactin levels showed consistently low levels during 24 h 3 out of the 7 lesioned animals and considerable fluctuations but no surge in the remaining 4 animals. Progesterone injections into the EB-treated rats with MBSC lesions did not elicit the marked surge in serum LH and FSH which was observed in sham-lesioned animals. In contrast, the EB-treated rats with MBSC lesions showed a significant rise of serum prolactin levels after progesterone injections, similar to that of sham lesioned animals. These results suggest that MBSC plays an essential role in the neural control of the steroid-induced surges of prolactin and gonadotropin release.