Abstract
Reproductive research in aging animals is often performed with very old rats manifesting spontaneous persistent estrus (SPE). However, Charles River (CD) Sprague Dawley rats present SPE as early as 6 months of age and thus are potentially very useful in such studies since the concomitant pathologies associated with old age can be avoided. Serum levels of LH, FSH, prolactin, estrogens, and progesterone were measured by RIA in 8 to 12 month SPE rats after rapid decapitation at 0300, 1000 or 1600 hr (8–11 rats/group). As reported by others in very old SPE rats, proiactin was high at 1600 hr (169±40 ng/ml) compared with levels at 0300 hr (43 ± 7 ng/ml) or 1000 hr (95 ± 25 ng/ml). LH and FSH values did not change with time of day, but those of FSH were consistently above baseline values of cyclic rats. Total estrogens were low (75 ± 9 pg/ml) at 1000 hr but significantly higher at both 0300 hr (127 ± 11.7 pg/ml) and 1600 hr (141 ± 23 pg/ml), resembling levels at about 1000 hr on proestrus in cyclic rats (125 ± 16 pg/ml). Average progesterone concentrations resembled baseline values of cyclic rats but varied widely (0.02 to 25 ng/ml). These findings suggest that the middle-aged SPE rat may be used in studies of the aging reproductive system, and that future studies with SPE rats should consider variations in prolactin, estrogen and progesterone with the time of day.
Similar content being viewed by others
References
Everett, J. W.: Spontaneous persistent estrus in a strain of albino rats. Endocrinology, 25: 123–127, 1939.
Everett, J. W.: Central neural control of reproductive functions of the adeno-hypophysis. Physiological Rev., 44: 373–431, 1964.
Aschheim, P.: Aging in the hypothalamic-hypophyseal ovarian axis in the rat, in The Hypothalamus, Pituitary and Aging, edited by Everitt, A. V. and Burgess, J. A., Charles C. Thomas, 1976, pp. 376–418.
Meites, J., Huang, H. H., and Simpkins, J. W.: Recent studies on neuroendocrine control of reproductive senescence in rats, in Aging, Vol. 4, The Aging Reproductive System, edited by Schneider, E. L., New York, Raven Press, 1978, pp. 213–235.
Meites, J., Steger, R. W., and Huang, H. H.: Relation of neuroendocrine system to the reproductive decline in aging rats and human subjects. Fed. Proc., 39: 3168–3172, 1980.
Damassa, D. A., Gilman, D. P., Lu, K. H., Judd, H. L., and Sawyer, C. H.: The twenty-four hour pattern of prolactin secretion in aging female rats. Biol. Reprod., 22: 571–575, 1980.
Miller, A. E., and Riegle, G. D.: Temporal changes in serum progesterone in aging female rats. Endocrinology, 106: 1579–1583, 1980.
Niswender, G. D., Midgley, A. R., Monroe, S. E., and Reichert, L. E., Jr.: Radioimmunoassay for rat LH with antiovine LH serum and ovine LH-131I. Proc. Soc. Exp. Biol. Med., 128:807–811, 1968.
Everett, J. W., Krey, L. C., and Tyrey, L.: The quantitative relationship between electrochemical preoptic stimulation and LH release in proestrus versus late diestrus rats. Endocrinology, 93: 947–953, 1973.
Aksel, S., Schomberg, D. W., Tyrey, L., and Hammond, C. B.: Vasomotor symptoms, serum estrogens and gonadotropin levels in surgical menopause. Am. J. Obstet. Gynecol., 126: 165–169, 1976.
Schomberg, D. W., Stouffer, R. L., and Tyrey, L.: Modulation of progestin secretion in ovarian cells by 17 β-hydroxy-5α-androstan-3-one (dihydrotestosterone): A direct demonstration in monolayer culture. Biochem. Biophys. Res. Comm., 68: 77–81, 1976.
Beach, J. E., Tyrey, L., and Everett, J.W.: Serum prolactin and LH in early phases of delayed and direct pseudopregnancy in the rat. Endocrinology, 96: 1241–1246, 1975.
Huang, H. H., Steger, R. W., Bruni, J. F., and Meites, J.: Patterns of sex steroid and gonadotropin secretion in aging female rats. Endocrinology, 103: 1855–1859, 1978.
Lu, K. H., Hopper, B. R., Vargo, L. M., and Yen, S. C. C.: Chronological changes in sex steroid gonadotropin and prolactin secretion in aging female rats displaying different reproductive states. Biol. Reprod., 21: 193–204, 1979.
Mann, D. R., and Barraclough, C. A.: Changes in peripheral plasma progesterone during the rat 4-day estrus cycle; an adrenal diurnal rhythm. Proc. Soc. Exp. Biol. Med., 142: 1226–1229, 1973.
Shaikh, A. A., and Shaikh, S. A.: Adrenal and ovarian steroid secretion in the rat estrous cycle temporarily related to gonadotropins and steroid levels found in peripheral plama. Endocrinology, 96: 37–44, 1975.
Mann, D. R., Cost, M. G., Jacobson, C. D., and MacFarland, L. A.: Adrenal gland rhythmicity and pituitary regulation of adrenal steroid secretion. Proc. Soc. Exp. Biol. Med., 156: 441–445, 1977.
Campbell, C. S., Schwartz, N. B., and Gorski Firlit, M.: The role of adrenal and ovarian steroids in the control of serum LH and FSH. Endocrinology, 101: 162–172, 1977.
Freeman, M. E., and Sterman, J. R.: Ovarian steroid modulation of prolactin surges in cervically stimulated ovariectomized rats. Endocrinology, 102: 1915–1920, 1978.
Author information
Authors and Affiliations
About this article
Cite this article
Beach, J.E., Tyrey, L., Schomberg, D.W. et al. Nocturnal and diurnal levels of prolactin, LH, FSH, estrogens, and progesterone in middle-aged, spontaneously persistent estrous rats. AGE 6, 82–85 (1983). https://doi.org/10.1007/BF02432508
Issue Date:
DOI: https://doi.org/10.1007/BF02432508