Reflections on the attainment of puberty in the rat: have circadian signals a role to play in its onset?

Mackinnon, P. C. B.; Puig-Duran, E.; Laynes, Robert

doi:10.1530/jrf.0.0520401

Cited by 42 publications

(18 citation statements)

References 59 publications

(69 reference statements)

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“…A similar result was described by Vomachka and Greenwald [27]. They tried to explain the finding using a proposition from a previous rat study [28], and speculated that FSH induces LH receptors at first and subsequently testicular testosterone output [27]. On the other hand, Ariyaratne and Mendis-Handagama [29] demonstrated that testicular production of testosterone in vitro kept low levels until 40 days of age, and progressively increased until 60 days old in the developing rat.…”

Section: Discussionsupporting

confidence: 62%

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Itoh

Kishi

Ohshima

et al. 2002

Journal of Reproduction and Development

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Abstract. We studied developmental reproduction of male golden hamsters (Mesocricetus auratus) by determining hormone secretion, observing morphological changes including distribution of immunoexpression of inhibin α subunit, 3β-hydroxysteroid dehydrogenase (HSD), and investigating sperm head count from birth to adulthood. Immunoexpression of inhibin α subunit was found in interstitial cells of not well organized testes of neonatal animals, and positive staining was also found in Sertoli cells in developing animals. However, the intensity of immunostaining in Sertoli cells varied when the spematogenic cycle of the seminiferous epithelium began. Testosterone levels in the plasma and testicular contents of testosterone and immunoreactive (ir)-inhibin increased from around 25 days of age, about 10 days before the presence of the first sperm in the testis. On the other hand, plasma concentrations of ir-inhibin progressively increased from birth to 10 days of age, when it reached peak levels. A reciprocal pattern of change between plasma concentrations of ir-inhibin and FSH was found from 10 days of age. Plasma concentrations and pituitary contents of LH increased from 15 days of age and reached adult levels about 40 days of age. The present results suggest that inhibin is an important factor in the regulation of FSH secretion even in infant male golden hamsters, and the regulated FSH may control the increasing the number of germ cells. Inhibin might be not the only endocrine factor as the regulator of FSH secretion, but also a paracrine or autocrine factor which is involved in spermatogenesis in the golden hamster. Key words: Inhibin, Hamster, Development, Testis (J. Reprod. Dev. 48: [343][344][345][346][347][348][349][350][351][352][353] 2002) arly 20 th century experiments, which were the initial proposal for the existence of inhibin, showed that destruction of the germinal epithelium by irradiation caused hyperfunction in the absence of atrophy of the second sex glands [1], and that injection of aqueous testicular extracts to castrated rats prevented the appearance of enlarged "castration cells" in the pituitary [2,3]. These

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Section: Discussionsupporting

confidence: 62%

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Itoh

Kishi

Ohshima

et al. 2002

Journal of Reproduction and Development

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“…A modi¬ fication of the rhythm of secretion of corticosterone during the prepubertal period has similarly been ob¬ served in other avian species (Meier & Dusseau, 1973;Wilson et al 1982) and in the rat (MacKinnon et al 1978;Ramaley, 1978). It is possible that development of a diurnal rhythm of secretion of a gonadal steroid, in response to the prepubertal increase in the secretion of LH, may have modified the corticosterone rhythm.…”

Section: Discussionmentioning

confidence: 87%

“…Previous studies have reported changes, during sexual development, in both the amplitude and phasing of the circadian rhythm of secretion of corticosteroids in several classes of vertebrates including mammals (rat: MacKinnon, Puig-Duran & Laynes, 1978;Ramaley, 1978), birds (white-throated sparrow: Dusseau & Meier, 1971; domestic duck: Wilson, Cunningham & Morris, 1982), Amphibia (European green frog: Dupont, Bourgeois, Reinberg & Vaillant, 1979) and fish (goldfish: Peter, Hontela, Cook & Paulencu, 1978; gulf killifish: Garcia & Meier, 1973).…”

Section: Introductionmentioning

confidence: 99%

Developmental changes in the diurnal rhythm of secretion of corticosterone and LH in the domestic hen

Wilson¹,

Jennings²,

Cunningham³

1984

Journal of Endocrinology

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When diurnal changes in the plasma concentrations of corticosterone and LH were compared at various times during sexual development a diurnal rhythm in the secretion of corticosterone was most pronounced at 4.5 weeks of age in hens maintained on a schedule of 8 h light: 16 h darkness (8L: 16D) and at 8.5 weeks of age in hens maintained on 16L: 8D. At these ages the phase-angle of the rhythm in relation to the onset of darkness was 3 h earlier than had been observed in previous studies of the adult hen. The characteristics of the corticosterone rhythm changed during sexual development and diurnal changes were no longer evident in hens at 17 weeks of age at a time when prepubertal plasma concentrations of LH were maximal. However, there was a tendency for plasma concentrations of corticosterone to fluctuate diurnally in hens studied at less than 10 days before the onset of lay although not to the same extent as has previously been observed in the adult hen. This period of development was associated with a pronounced increase in the plasma concentration of progesterone. An increase in the plasma concentration of LH at the onset of darkness was observed at all ages in hens maintained on either photoschedule . In hens of 4.5-15 weeks of age maintained on 16L: 8D or 8L: 16D this increase in the plasma concentration of LH was sustained during the first 5 or 8-11 h of darkness respectively but at 17 weeks of age only a transient increase in LH was seen at the onset of darkness. Plasma concentrations of LH in samples of plasma taken at intervals of between 3 days and 2 weeks throughout sexual development were, until 18-19 weeks, consistently higher in hens maintained on a photoschedule of 16L: 8D than on 8L: 16D.

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“…Studies of plasma gonadotrophin concentrations before puberty show that final maturation and/or activation of the oestradiol signalling system of the ovary occurs in the absence of any dramatic signal from the pituitary gland (Döhler & Wuttke, 1975;Chiappa & Fink, 1977ft). Subtle signals, however, in the form of episodic or diurnal gonadotrophin release cannot be excluded (MacKinnon et al 1978). Notwithstanding the broad similarities between the mechanisms that subserve the pubertal and the 'adult' gonadotrophin surge, there are differences with respect to detail.…”

Section: Discussionmentioning

confidence: 99%

Mechanism of the First Spontaneous Gonadotrophin Surge and That Induced by Pregnant Mare Serum and Effects of Neonatal Androgen in Rats

Sarkar¹,

Fink²

1979

Journal of Endocrinology

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The mechanism of the first (pubertal) preovulatory gonadotrophin surge was investigated in Wistar rats by measuring (1) LH releasing factor (LH-RF) in pituitary stalk plasma and in extracts of hypothalamic and preoptic tissue, (2) LH and FSH in peripheral plasma and extracts of anterior pituitary tissue and (3) the LH and FSH response to LH-RF. The mechanism of the first surge appeared broadly to resemble that in the adult. That is, the gonadotrophin surge which occurs on the afternoon of the day before vaginal opening was found to coincide with a surge of immunoreactive LH-RF in pituitary stalk plasma and a significant increase in pituitary responsiveness to LH-RF. The magnitude of the change in pituitary responsiveness was, however, less at puberty than in the adult while the peak of the LH-RF surge was higher at puberty. The surges of LH-RF in stalk plasma and gonadotrophin in peripheral plasma corresponded relatively precisely with a fall in the preoptic and hypothalamic content of LH-RF and in the pituitary content of LH and FSH, suggesting that, in contrast with the adult, the synthesis of LH-RF and gonadotrophin at puberty cannot keep up with their release. A significant increase in stalk plasma LH-RF concentration occurring concomitantly with a surge of LH could be induced on the afternoon of Day 32 of life by administering pregnant mare serum (PMS) ON Day 30 (about 10 days before vaginal opening). This, together with other evidence, suggests that the timing of the first gonadotrophin surge depends upon the capacity of the ovary to secrete oestradiol in the form of a surge. The fact that no significant increase in the pituitary responsiveness to LH-RF occurred in PMS-treated rats could account for the fact that the height of the gonadotrophin surge in these animals is only a third that of the spontaneous surge. No significant change in peripheral plasma LH or stalk plasma LH-RF concentrations was found around the time of vaginal opening or cornification in female rats given 1.25 mg testosterone propionate on Day 4 (androgenized female rats). Studies on the effect of ovariectomy and/or adrenalectomy suggested that the ovary and adrenal are involved in the timing of vaginal opening in normal but not in androgenized female animals.

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Reflections on the attainment of puberty in the rat: have circadian signals a role to play in its onset?

Cited by 42 publications

References 59 publications

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Developmental changes in the diurnal rhythm of secretion of corticosterone and LH in the domestic hen

Mechanism of the First Spontaneous Gonadotrophin Surge and That Induced by Pregnant Mare Serum and Effects of Neonatal Androgen in Rats

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