Advertisement

How does the Gonad Affect LHRH Secretion? Effects of Gonadectomy on LHRH Release from Median Eminence Nerve Terminals Incubated In Vitro and on LHRH Concentration in Hypophyseal Portal Blood

  • M. M. Valenca
  • M. Ching
  • C. Masotto
  • A. Negro-Vilar
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 219)

Abstract

It is well established that the central nervous system exerts an important influence on many aspects of reproductive function, particularly by controlling the secretion of pituitary gonadotropins. This is accomplished by way of specific brain messengers which, in turn, regulate pituitary endocrine function. The primary hypothalamic hormonal messenger regulating luteinizing hormone (LH) secretion is the decapeptide LHRH, which is synthetized as a large molecular weight prohormone in the neuronal cell bodies. After axonal transport, the mature decapeptide LHRH is stored in nerve terminals in the median eminence (ME) from which it is secreted into the hypophyseal portal circulation. The secretion of LHRH seems to be under the influence of multifactorial regulatory mechanisms in which numerous extracellular messengers may participate, including the catecholamines (Negro-Vilar et al., 1979), peptides (Valenca et al., 1985; Kalra and Kalra, 1984) and sex steroid hormones (Rudenstein et al., 1979; Kalra and Kalra, 1984). A review of some of these regulatory mechanisms is included in this volume (see chapter by Negro-Vilar, Valenca and Culler).

Keywords

Luteinizing Hormone Median Eminence Luteinizing Hormone Level Pituitary Gonadotropin LHRH Release 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Carmel PW, Antunes JL, Ferin M, 1979. Collection of blood from the pituitary stalk and portal veins in monkeys, and from the pituitary sinusoidal system of monkey and man. J Neurosurg 50:75–80PubMedCrossRefGoogle Scholar
  2. Carmel PW, Araki S, Ferin M, 1976. Pituitary stalk portal blood collection in rhesus monkeys: evidence for pulsatile release of gonadotropinreleasing hormone (GnRH). Endocrinology 99:243–48PubMedCrossRefGoogle Scholar
  3. Ching M, 1982. Correlative surges of LHRH, LH and FSH in pituitary stalk plasma and systemic plasma of rat during proestrus: effect of anesthetics. Neuroendocrinology 34:279–84PubMedCrossRefGoogle Scholar
  4. Clayton RN, Popkin RM, Fraser HM, 1982. Hypothalamic regulation of pituitary gonadotropin-releasing hormone receptors: effects of gonadotropin-releasing hormone immunoneutralization. Endocrinology 110:1116–23PubMedCrossRefGoogle Scholar
  5. Culler MD, Negro-Vilar A, 1986. Evidence that pulsatile follicle-stimulating hormone secretion is independent of endogenous luteinizing hormone-releasing hormone. Endocrinology 118:609–12PubMedCrossRefGoogle Scholar
  6. Dluzen DE, Ramirez VD, 1985. In-vivo activity of the LH-releasing hormone pulse generator in castrated and intact male rats. J Endocr 107:331–40PubMedCrossRefGoogle Scholar
  7. Eskay RL, Mical RS, Porter JC, 1977. Relationship between luteinizing hormone releasing hormone concentration in hypophyseal portal blood and luteinizing hormone release in intact, castrated, and electrochemically stimulated rats. Endocrinology 100:263–70PubMedCrossRefGoogle Scholar
  8. Kalra PS, Crowley WR, Kalra SP, 1987. Differential in vitro stimulation by Naloxone and K+ of luteinizing hormone-releasing hormone and catecholamine release from the hypothalami of intact and castrated rats. Endocrinology 120:178–85.PubMedCrossRefGoogle Scholar
  9. Kalra SP, Kalra PS, 1984. Opioid-adrenergic-steroid connection in regulation of luteinizing hormone secretion in the rat. Neuroendocrinology 38:418–26PubMedCrossRefGoogle Scholar
  10. Morrell JI, Schwanzel-Fukuda M, Fahrbach SE, Pfaff DW, 1984. Axonal projections and peptide content of steroid hormone concentrating neurons. Peptides 5:227–39PubMedCrossRefGoogle Scholar
  11. Negro-Vilar A, Ojeda SR, McCann SM, 1979. Catecholaminergic modulation of luteinizing hormone-releasing hormone release by median eminence terminals in vitro. Endocrinology 104:1749–57PubMedCrossRefGoogle Scholar
  12. Rudenstein RS, Bigdeli H, McDonald MH, Snyder PJ, 1979. Administration of gonadal steroids to the castrated male rat prevents a decrease in the release of gonadotropin-releasing hormone from the incubated hypothalamus. J Clin Invest 63:262–67PubMedCrossRefGoogle Scholar
  13. Sar M, 1984. Estradiol is concentrated in tyrosine hydroxylase-containing neurons of the hypothalamus. Science 223:938–40PubMedCrossRefGoogle Scholar
  14. Valenca MM, Johnston CA, Negro-Vilar A, 1985. Gonadal inhibitory effects of LHRH analogs: evidence for a hypothalamic site of action mediated by opiate peptides. J Andrology (supp) 6:41Google Scholar
  15. Weiland NG, Barraclough CA, Catt KJ, 1986. Effects of long- and short-term gonadectomy on the hypothalamo-hypophysial (LH-releasing hormone-LH) system in oestrogen-treated male and female rats. J Endocr 110:367–73PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • M. M. Valenca
    • 1
  • M. Ching
    • 1
  • C. Masotto
    • 1
  • A. Negro-Vilar
    • 1
  1. 1.Reproductive Neuroendocrinology Section, LRDT, National Institute of Environmental Health SciencesNational Institutes of HealthUSA

Personalised recommendations