Immunocytochemical and histochemical analyses of gonadotrophin releasing hormone, tyrosine hydroxylase, and cytochrome oxidase reactivity within the hypothalamus of chicks showing early sexual maturation

1993 ◽  
Vol 99 (3) ◽  
pp. 221-229 ◽  
Author(s):  
Gregory S. Fraley ◽  
Wayne J. Kuenzel
Keyword(s):  
Tyrosine Hydroxylase ◽  
Cytochrome Oxidase ◽  
Sexual Maturation ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

HYPOTHALAMIC, PITUITARY AND TESTICULAR FUNCTION DURING SEXUAL MATURATION OF THE MALE RAT

1977 ◽  
Vol 72 (1) ◽  
pp. 17-26 ◽  
Author(s):  
A. H. PAYNE ◽  
R. P. KELCH ◽  
E. P. MURONO ◽  
J. T. KERLAN
Keyword(s):  
Dehydrogenase Activity ◽  
Sexual Maturation ◽  
Hydroxysteroid Dehydrogenase ◽  
Male Rat ◽  
Releasing Hormone ◽  
Isomerase Activity ◽  
Serum Lh ◽  
Rate Of Increase ◽  
Gonadotrophin Releasing Hormone

SUMMARY Hypothalamic content of gonadotrophin-releasing hormone (GnRH), serum LH and FSH, capacity of the testis to synthesize testosterone in vitro, and testicular 5-ene-3β-hydroxysteroid dehydrogenase-isomerase and 17β-hydroxysteroid dehydrogenase were measured in groups of rats at approximately 5 day intervals from birth to day 64 and at days 74 and 89. The capacity of the testes to synthesize testosterone in vitro was measured in the presence of a saturating dose of rat LH. Gonadotrophin-releasing hormone increased steadily from 0·17 ng per hypothalamus at birth to a maximum of 7 ng at day 52 and then remained constant. LH concentrations were highly variable and often exceeded adult values between days 10 and 32. After day 32 a steady rise was observed which reached adult values between days 37 and 42. FSH concentrations markedly increased from 255 ng/ml observed at birth and day 10 to a peak value of 1000 ng/ml at day 32. Subsequently there was a steady decline in FSH values until day 74 when the concentration returned to values found at birth. 5-ene-3β-Hydroxysteroid dehydrogenase-isomerase activity exhibited a rapid increase between days 12 and 19 followed by an even greater rate of increase between days 19 and 32 when adult levels were attained. 17β-Hydroxysteroid dehydrogenase activity was very low between birth and day 22. Enzyme activity began to increase at day 22 with a rapid increase in activity observed between days 37 and 58. The increase in capacity to synthesize testosterone closely followed the increase in 17β-hydroxysteroid dehydrogenase activity. The study demonstrates that during sexual maturation in the male rat, changes in serum LH and FSH do not reflect changes in hypothalamic GnRH. The appearance of Leydig cells as monitored by 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity precedes by approximately 20 days the increase in testicular capacity to synthesize testosterone in vitro. The latter coincides with the increase in 17β-hydroxysteroid dehydrogenase activity. These results suggest that 17β-hydroxysteroid dehydrogenase is a limiting factor in the ability of the testis to respond to LH stimulation.

Sexual maturation of male rats treated postnatally with a gonadotrophin-releasing hormone antagonist

1988 ◽  
Vol 116 (2) ◽  
pp. 241-246 ◽  
Author(s):  
K.-L. Kolho ◽  
H. Nikula ◽  
I. Huhtaniemi
Keyword(s):  
Sexual Maturation ◽  
Gnrh Antagonist ◽  
Prolactin Receptor ◽  
Male Rats ◽  
Delayed Puberty ◽  
Testis Weight ◽  
Adult Rats ◽  
Releasing Hormone ◽  
Treatment Groups ◽  
Gonadotrophin Releasing Hormone

ABSTRACT Postnatal secretion of gonadotrophin by male rats was inhibited by a potent gonadotrophin-releasing hormone (GnRH) antagonist analogue (N-Ac-4-Cl-d-Phe1,4-Cl-d-Phe2,d-Trp3,d-Phe6,des-Gly10-GnRH-d-alanylamide; Org 30039; 2 mg/kg s.c. twice daily) on days 1–5, 6–10, 11–15 or 16–20 of life. The onset of puberty was determined by monitoring the separation of the preputium from the glans penis, i.e. balanopreputial separation (BPS). Rats treated on days 1–5 matured normally, whereas all treatments between days 6 and 20 delayed BPS (P < 0·01). In adult rats (between 110 and 160 days of age), testis weights were reduced by 21–35% (P < 0·01) in groups treated between days 1 and 15, although weights of the accessory sex glands were normal. Testicular FSH receptors were decreased by 31–47% (P < 0·01) in all treatment groups, whereas the LH receptor content was decreased only in rats treated between days 1 and 5 (18%; P < 0·05) and prolactin receptor content decreased only in rats treated up to day 10 (31–33%; P < 0·01). Concentrations of serum testosterone, LH and FSH, and pituitary contents of LH and FSH were unaffected by neonatal treatment with Org 30039. Animals treated with Org 30039 had reduced fertility which was most pronounced (88%; P < 0·01) in rats treated between days 1 and 5. However, motile sperm were detectable in the cauda epididymis of the infertile rats. In conclusion, postnatal gonadotrophin deprivation induced with a GnRH antagonist for different 5-day periods during the first 15 days of life delayed puberty, reduced adult testis weight and impaired fertility. Some effects of the antagonist were largely independent of the timing of gonadotrophin suppression. Other effects, including suppression of testicular LH and prolactin receptors and the delay in the onset of puberty, were found only in the younger and older treatment groups respectively. These findings emphasize the importance of neonatal hypothalamic-pituitary-gonadal function for subsequent sexual maturation. J. Endocr. (1988) 116, 241–246

Sexual maturation in starlings raised on long or short days: changes in hypothalamic gonadotrophin-releasing hormone and plasma LH concentrations

1989 ◽  
Vol 123 (2) ◽  
pp. 189-196 ◽  
Author(s):  
A. Dawson ◽  
A. R. Goldsmith
Keyword(s):  
Sexual Maturation ◽  
Releasing Hormone ◽  
Short Day ◽  
Nest Boxes ◽  
Adult Plumage ◽  
Gonadotrophin Releasing Hormone ◽  
Testicular Size ◽  
Induced Changes ◽  
Short Days

ABSTRACT Is the extended prepubertal period which occurs in most birds due to a juvenile photorefractoriness analogous to photorefractoriness in adults? Starlings were taken from nest boxes 4 days after hatching and hand-reared on long days or short days. In females on long days, hypothalamic gonadotrophin-releasing hormone (GnRH) content and plasma LH concentration remained low. In intact males on long days, plasma LH remained low and the testes remained small, and in castrated birds, plasma LH also remained low. In females reared on short days, hypothalamic GnRH content began to increase dramatically from 4 weeks of age and plasma LH increased from 6 weeks of age. In intact males on short days, there was a slight increase in plasma LH and testicular size, and in castrated males, plasma LH increased markedly from six weeks of age. All birds on long days moulted into adult plumage, whereas those on short days retained juvenile plumage. The changes in birds reared on short days were similar to those found when photorefractory adult birds are transferred to short days. This adds to the evidence that juvenile photorefractoriness is analogous to photorefractoriness in adults, and therefore that the seasonal termination of photorefractoriness is an annual puberty. However, the responses to short days occur later in birds raised on short days than in older birds transferred to short days, which suggests either that short day-induced changes occur more slowly in young birds, or that birds only respond to short days after a certain age. Journal of Endocrinology (1989) 123, 189–196

Temporal relationship between the onset of daily gonadotrophin surges and of puberty in female golden hamsters

1986 ◽  
Vol 108 (2) ◽  
pp. 219-224 ◽  
Author(s):  
R. S. Donham ◽  
N. Creyaufmiller ◽  
T. J. Lyons ◽  
M. H. Stetson
Keyword(s):  
Sexual Maturation ◽  
Vaginal Discharge ◽  
Daily Rhythm ◽  
Daily Injection ◽  
Daily Rhythms ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone ◽  
Age At Puberty ◽  
Phenobarbital Sodium ◽  
The Brain

ABSTRACT Daily rhythms of LH and FSH release commence on day 16 or 17 of age in the prepubertal female golden hamster, 2–3 weeks before regular 4-day oestrous cycles begin. We tested the hypothesis that the daily surges of gonadotrophin regulate, at least in part, rate of sexual maturation and, hence, age at puberty. We predict that an advance or a delay in the initiation of the daily rhythm should result in a corresponding advance or delay in the day of puberty. In the first test, the onset of daily gonadotrophin surges was advanced by gonadotrophin-releasing hormone (GnRH) injections; in the second test, the onset was delayed by daily injection of phenobarbital sodium (PB). The day of the first of at least three consecutive post-ovulatory vaginal discharges was used as an index of the age at puberty. Gonadotrophin-releasing hormone (50 ng/0·1 ml saline per animal) was injected at 16.30 h on days 8–17 of age. These injections initiated a daily mid-afternoon surge of LH about 8 days before the onset of the daily rhythm of gonadotrophins in salineinjected controls and the day of first vaginal discharge was advanced by 4 days compared with saline-injected controls (32·0±1·8 days vs 36·3±1·0 days; P < 0·001). Phenobarbital sodium (100 mg/kg body wt), injected at 13.30 h from 16 to 25 days of age, blocked daily surges of gonadotrophin observed in controls by day 18. These injections of PB delayed by about 8 days the appearance of daily LH surges and the day of first vaginal discharge was delayed 8 days compared with saline-injected controls (43·0±1·2 vs 35·4±1·1; P<0·001). Control animals injected with PB after the critical period, i.e. at a time when daily gonadotrophin surges are not affected, demonstrated first vaginal oestrus at the same age as saline-injected controls. These results support the proposal that daily rhythms of hormone release by the brain and pituitary regulate the processes of sexual maturation. J. Endocr. (1986) 108, 219–224

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