Lack of effect of noradrenergic denervation of the hypothalamus and medial preoptic area on the feedback regulation of gonadotropin secretion and the estrous cycle of the rat

G. Nicholson, G. Greeley, J. Humm, W. Youngblood, J. S. Kizer

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    Abstract

    In order to determine the effect of noradrenergic denervation of the hypothalamus and preoptic area on the regulation of gonadotropin secretion in the rat, bilateral injections of 6-OH-dopamine (8 μg free base in 2 μl) or vehicle were made in caudal, ventral pons. After the placement of such lesions, concentrations of norepinephrine were markedly reduced throughout the hypothalamus and preoptic area (median eminence, 60-76%; arcuate nucleus, 75-80%; dorsomedial nucleus, 65-81%; suprachiasmatic nucleus, 70%; periventricular nucleus, 85%; paraventricular nucleus, 74%; ventromedial nucleus, 82%; and medial preoptic area, 82%), whereas concentrations of dopamine in these same areas were unchanged. Despite the placement of such lesions, serum LH and FSH levels in both intact and castrated rats were not significantly different from FSH and LH values in nonlesioned controls (intact and castrated). In addition, all lesioned female animals reinitiated consecutive 4-day estrous cycles, with the mean number of days between surgery and reinitiation of estrous being identical to that of controls. From these findings, two conclusions seem warranted: 1) nuclei within the hypothalamus and preoptic area receive the vast majority of their noradrenergic innervation by the ventral norepinephrine bundle, and 2) normal regulation of LH and FSH secretion in castrated and intact males as well as in normally cycling females is possible despite a substantial denervation of the noradrenergic innervation of the hypothalamus and medial preoptic area.

    Original languageEnglish (US)
    Pages (from-to)559-566
    Number of pages8
    JournalEndocrinology
    Volume103
    Issue number2
    StatePublished - 1978

    Fingerprint

    Preoptic Area
    Estrous Cycle
    Denervation
    Gonadotropins
    Hypothalamus
    Dopamine
    Norepinephrine
    Mediodorsal Thalamic Nucleus
    Median Eminence
    Arcuate Nucleus of Hypothalamus
    Suprachiasmatic Nucleus
    Pons
    Paraventricular Hypothalamic Nucleus
    Ambulatory Surgical Procedures
    Injections
    Serum

    ASJC Scopus subject areas

    • Endocrinology
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Lack of effect of noradrenergic denervation of the hypothalamus and medial preoptic area on the feedback regulation of gonadotropin secretion and the estrous cycle of the rat. / Nicholson, G.; Greeley, G.; Humm, J.; Youngblood, W.; Kizer, J. S.

    In: Endocrinology, Vol. 103, No. 2, 1978, p. 559-566.

    Research output: Contribution to journalArticle

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    abstract = "In order to determine the effect of noradrenergic denervation of the hypothalamus and preoptic area on the regulation of gonadotropin secretion in the rat, bilateral injections of 6-OH-dopamine (8 μg free base in 2 μl) or vehicle were made in caudal, ventral pons. After the placement of such lesions, concentrations of norepinephrine were markedly reduced throughout the hypothalamus and preoptic area (median eminence, 60-76{\%}; arcuate nucleus, 75-80{\%}; dorsomedial nucleus, 65-81{\%}; suprachiasmatic nucleus, 70{\%}; periventricular nucleus, 85{\%}; paraventricular nucleus, 74{\%}; ventromedial nucleus, 82{\%}; and medial preoptic area, 82{\%}), whereas concentrations of dopamine in these same areas were unchanged. Despite the placement of such lesions, serum LH and FSH levels in both intact and castrated rats were not significantly different from FSH and LH values in nonlesioned controls (intact and castrated). In addition, all lesioned female animals reinitiated consecutive 4-day estrous cycles, with the mean number of days between surgery and reinitiation of estrous being identical to that of controls. From these findings, two conclusions seem warranted: 1) nuclei within the hypothalamus and preoptic area receive the vast majority of their noradrenergic innervation by the ventral norepinephrine bundle, and 2) normal regulation of LH and FSH secretion in castrated and intact males as well as in normally cycling females is possible despite a substantial denervation of the noradrenergic innervation of the hypothalamus and medial preoptic area.",
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