• Smith, M (Susan) (PI)

    Project: Research project

    Project Details


    Postpartum lactation in humans and monkeys is associated with ovarian
    quiescence attributed to suckling-induced deficits in GnRH secretion and
    hyperprolactinemia. The work proposed in this application would
    investigate the validity and nature of these mechanisms in the rhesus
    monkey, a primate in which the control of gonadotropin secretion and
    ovarian function appear similar to the human. 1. Because a reduced frequency of pulsatile GnRH release has the potential
    of disrupting normal gonadotropin secretion and ovarian cycles, the
    intermittent discharge of this hypothalamic hormone will be assessed
    indirectly by measuring pulsatile LH release in chronically catheterized
    monkeys nursing their infants. Moreover, changes in pulsatile LH release
    that might occur following abrupt removal of the infant will be recorded at
    several postpartum intervals. To relate the intensity of the suckling
    stimulus to the duration of gonadotropin suppression during lactation, some
    rhesus infants will be retricted to mother's milk during the usual period
    of weaning in an attempt to delay resumption of maternal pituitary function
    as assessed by pulsatile LH secretion and the positive feedback action of
    estradiol. 2. The possibility that the sensitivity of the hypothalamic-pituitary axis
    to the negative feedback action of estrogen is enhanced during lactation
    will be tested in ovariectomized monkeys bearing estradiol capsules that
    produce low circulating levels of the steroid. 3. Exogenous pulses of GnRH will be administered to nursing monkeys in an
    attempt to re-initiate pituitary and ovarian function. Moreover, the
    possible role of progesterone in mediating the inhibitory action of
    lactational hyperprolactinemia on ovarian follicular development will be
    investigated in monkeys with hypothalamic lesions receiving pulsatile GnRH
    replacement and progesterone capsules. 4. The central neural mechanisms underlying the inhibition of GnRH
    secretion in lactating monkeys will be studied by measuring pulsatile LH
    release during suckling following administration of antagonists to the
    endogenous opioid peptides, dopamine, and serotonin. These studies, which are difficult to perform under suitable controlled
    conditions in humans, will serve to delineate the mechanisms involved in
    lactational amenorrhea in a primate model.
    Effective start/end date9/1/868/31/91


    • National Institutes of Health


    • Medicine(all)


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