Ovarian and Hypothalamic Control of the Daily Surges of Prolactin Secretion During Pseudopregnancy in the Rat

M. E. Freeman, M. S. Smith, S. J. Nazian, J. D. Neill

    Research output: Contribution to journalArticle

    190 Scopus citations

    Abstract

    Cervical stimulation in the rat institutes a pattern of prolactin secretion consisting of two daily surges, one diurnal and one nocturnal, which continue for the greater part of pseudopregnancy. This contrasts with the diestrous day 1-2 interval of the estrous cycle wherein prolactin levels are low and relatively unchanging. A variety of noxious procedures such as aortic cannulation and serial blood sampling, sham ovariectomy and sham surgical cuts in the hypothalamus selectively and temporarily suppresses the diurnal prolactin surges of pseudopregnancy; the nocturnal surges remained unaffected. In the absence of the ovaries (removed on day 0 of pseudopregnancy) the diurnal prolactin surges have disappeared no later than day 5, whereas the nocturnal surges are present at day 6 but have disappeared by day 10. Hypothalamic retrochiasmatic cuts abolish immediately both surges. These results demonstrate the existence of an apparently unique kind of neuroendocrine reflex, copulation-induced, which results in repeated nocturnal surges of prolactin secretion at daily intervals for a prolonged period of time in response to a brief 1-min stimulus. To account for these observations, a hypothalamic mnemonic system has been postulated which is activated by cervical stimulation and which retains and expresses this information repeatedly even in the absence of the ovaries.

    Original languageEnglish (US)
    Pages (from-to)875-882
    Number of pages8
    JournalEndocrinology
    Volume94
    Issue number3
    DOIs
    StatePublished - Mar 1974

    ASJC Scopus subject areas

    • Endocrinology

    Fingerprint Dive into the research topics of 'Ovarian and Hypothalamic Control of the Daily Surges of Prolactin Secretion During Pseudopregnancy in the Rat'. Together they form a unique fingerprint.

  • Cite this