Summary
The effects of coitus on the ultrastructure of neurons in the suprachiasmatic nucleus of the rabbit were studied. Changes first became apparent 1/2 h after coitum in neurons located near capillaries. More pronounced ultrastructural changes were observed in large neurons removed at 1 h post-coitus. These changes, characterized by well developed Golgi systems and rough endoplasmic reticulum, the presence of large dense-core vesicles and a significant increase in both neuronal and nuclear size, were also evident in neurons observed at 2 to 10 h post coitum. Similar ultrastructural features were not observed in the neurons of the control animals. The post-coital ultrastructural changes observed within these neurons suggest high synthetic activity which may concern the production sites of the neurohormone LH-RF. Two populations of dense-core vesicles were observed: a) those with a mean diameter of 849 Å, and b) those with a mean diameter of 1542 Å. The small dense-core vesicle is probably monoamine in nature; the larger vesicle may contain the neurohormone LH-RF. A third vesicle type with a mean diameter of 1836 Å and characterized by a granular content of low electron density was also observed. That this vesicle represents the immature form of the large (1542 Å) dense-core vesicle is suggested; however, morphological evidence supporting this hypothesis is inconclusive. There is also no evidence for the storage of secreted materials within the soma of these neurons. Immediate transport toward the median eminence is suggested.
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References
Aghajanian, G. K., Bloom, F. E., Heard, M. H.: Electron microscopy of degeneration within the serotonin pathway of rat brain. Brain Res. 13, 266–273 (1969).
Barraclough, C. A.: Modification in reproductive function after exposure to hormone during prenatal and early postnatal period: In: Neuroendocrinology, vol. II (L. Martini and W.F. Ganong, eds.), p. 61–99. New York: Academic Press 1967.
— Yrarrazaval, S., Hatton, R.: A possible hypothalamic site of action of progesterone in the facilitation of ovulation in the rat. Endocrinology 75, 383–845 (1964).
Clattenburg, R. E., Singh, R. P., Montemurro, D. G.: Ultrastructural changes in the preoptic nucleus of the rabbit following coitus. Neuroendocrinology 8, 289–306 (1971).
Crighton, D. B., Schneider, H. P. G., McCann, S. M.: Localization of LH-Releasing factor in the hypothalamus and neurohypophysis as determined by an in vitro method. Endocrinology 87, 323–329 (1970).
Donovan, B. T., Harris, G. W.: Adrenergic agents and the release of gonadatrophic hormones in the rabbit. J. Physiol. (Lond.) 132, 577–585 (1965).
Everett, J. W.: The preoptic region of the brain and its relation to ovulation. In: Control of ovulation (C. A. Villee, ed.), p. 101–112. New York: Pergamon Press 1961.
— Neuroendocrine aspects of mammalian reproduction. Rev. Physiol. 31, 383–416 (1969).
Flament-Durand, J.: Ultrastructural aspects of the paraventricular nuclei in the rat. Z. Zellforsch. 116, 61–69 (1971).
Frith, D. A., Hooper, K. C.: The effect of coitus on the activity of certain enzymes in the female rabbit hypothalamus. Acta endocr. (Kbl.) 66, 213–220 (1971).
Fuxe, K.: Evidence for the existence of monoamine neurons in the central nervous system. IV. The distribution of monoamine nerve terminals in the central nervous system. Acta physiol. scand. 64 (Suppl. 247) 37–85 (1965).
— Hökfelt, T.: Central monoaminergic systems and hypothalamic function. In: The hypothalamus (L. Martini, M. Motta and F. Frasciani, eds.), p. 123–138. New York: Academic Press 1970.
Gorski, R. A.: The neural control of ovulation. In: Biology of gestation, vol 1 (N.S. Assali, ed.), p. 1–66. New York: Academic Press 1968.
— Localization of hypothalamic regulation of anterior pituitary function. Amer. J. Anat. 129, 219–222 (1970).
Halász, B.: Endocrine function of hypothalamic islands. In: Progress in endocrinology (C. Gual, ed.), p. 508–514. Amsterdam: Excerpta Medica Foundation 1969.
Harris, G. W.: The induction of ovulation in the rabbit by electrical stimulation of the hypothalamus-hypophysial mechanism. Proc. roy. Soc. B 122, 374–394 (1937).
-- Electrical stimulation of the hypothalamus and the mechanism of neural control of the adenohypophysis. J. Physiol. (Lond.) 107–429 (1948).
— Ovulation. Amer. J. Obstet. Gynec. 105, 659–669 (1969).
— Naftolin, F.: The hypothalamus and the control of ovulation. Brit. med. Bull. 26, 3–9 (1970).
Haterius, H. O., Derbyshire, A. J.: Ovulation in the rabbit following upon the stimulation of the hypothalamus. Amer. J. Physiol. 119, 329–330 (1937).
Hilliard, J., Hayward, J. N., Sawyer, C. H.: Postcoital patterns of secretion of pituitary gonadotrophin and ovarian progestin in the rabbit. Endocrinology 75, 957–963 (1964).
Kalra, S. P., Sawyer, C. H.: Blockade of copulation-induced ovulation in the rat by anterior hypothalamic deafferentation. Endocrinology 87 (6), 1124–1128 (1970).
Koves, K., Halász, B.: Location of the neural structures triggering ovulation in the rat. Neuroendocrinology 6, 180–194 (1970).
McCann, S. M.: A hypothalamic luteinizing hormone releasing factor. Amer. J. Physiol. 202, 395–400 (1962).
Mess, B.: Site and onset of production of releasing factors: In: Progress in endocrinology (C. Gual, ed.), p. 564–570. Amsterdam: Excerpta Medica Foundation 1968.
Quinn, D. L.: Hypothalamic mechanisms involved in the control of gonadotrophic hormone secretion in the guinea pig: evidence of elevated brain thresholds to electrical stimulation in the medical preoptic-anterior hypothalamic region during “early” diestrous. Endocrinology 87, 343–349 (1970).
Sawyer, C. H., Everett, J. W., Markee, J. E.: A neural factor in the mechanism by which estrogen induces the release of luteinizing hormone in the rat. Endocrinology 44, 218–233 (1949).
Scharrer, E., Scharrer, B.: Secretory cells within the hypothalamus. Res. Publ. Ass. Res. nerv. ment. Dis. 20, 170–194 (1940).
Schneider, H. P. G., Crighton, R. G., McCann, S. M.: Suprachiasmatic LH-Releasing factor. Neuroendocrinology 5, 271–280 (1969).
Sloper, J. C., Bateson, R. G.: Ultrastructure of neurosecretory cells in the supraoptic nucleus of the dog and rat. J. Endocr. 31, 139–150 (1965).
Stutinsky, F. S.: Hypothalamic neurosecretion. In: The Hypothalamus (L. Martini, M. Motta, and F. Fraschini, eds.), p. 45–68. New York: Academic Press. 1970.
Teleisnik, S., Velasco, M., Astrada, J.: Effect of hypothalamic deafferentation on the control of luteinizing hormone secretion. J. Endocr. 46, 1–7 (1970).
Tejasen, T., Everett, J. W.: Surgical analysis of the preoptico-tuberal pathway controlling ovulatory release of gonadotropins in the rat. Endocrinology 81, 1387–1396 (1967).
Zambrano, D., De Robertis, E.: The secretory cycle of supraoptic neurons in the rat. Z. Zellforsch. 73, 414–431 (1966).
— The effect of castration upon the ultrastructure of the rat hypothalamus. II. Arcuate nucleus and outer zone of the median eminence. Z. Zellforsch. 87, 409–421 (1968).
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This investigation was supported by grants to the two senior authors from the Medical Research Council of Canada.
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Clattenburg, R.E., Singh, R.P. & Montemurro, D.G. Post-coital ultrastructural changes in neurons of the suprachiasmatic nucleus of the rabbit. Z.Zellforsch 125, 448–459 (1972). https://doi.org/10.1007/BF00306653
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DOI: https://doi.org/10.1007/BF00306653