PITUITARY HORMONE SECRETION IN THE GENETICALLY MALE RAT PSEUDOHERMAPHRODITE

1975 ◽  
Vol 64 (2) ◽  
pp. 249-255 ◽  
Author(s):  
A. S. GOLDMAN ◽  
A. W. ROOT ◽  
G. DUCKETT ◽  
B. H. SHAPIRO
Keyword(s):  
Growth Hormone ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Female Rats ◽  
Male Rat ◽  
Normal Male ◽  
Pituitary Hormone ◽  
Male And Female ◽  
Male And Female Rats ◽  
Serum Lh

SUMMARY Pituitary content or concentration of follicle-stimulating hormone (FSH), prolactin and growth hormone in the genetically androgen insensitive male rat pseudohermaphrodite is intermediate between normal male and female rats, while pituitary luteinizing hormone (LH) concentration and serum FSH levels are the same as in the normal male. The concentration of serum LH, prolactin and growth hormone indicates no sexual dimorphism. Although the pseudohermaphrodite is genetically male with a female phenotype, our results suggest some degree of masculinization of the hypothalamicpituitary system.

Growth hormone responses to multiple injections of a fragment of human growth hormone-releasing factor in conscious male and female rats

1985 ◽  
Vol 106 (3) ◽  
pp. 281-289 ◽  
Author(s):  
R. G. Clark ◽  
I. C. A. F. Robinson
Keyword(s):  
Growth Hormone ◽  
Human Growth ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Male And Female ◽  
Gh Secretion ◽  
Male And Female Rats ◽  
Hormone Responses ◽  
Males And Females

ABSTRACT The GH responses to single i.v. injections of GH-releasing factor (GRF) in conscious male rats are highly variable. Although normal male rats show a pulsatile secretory pattern of GH with pulses occurring at intervals of 3–3·5 h, the peaks occur at different times in individual animals. We have compared the GH responses of young conscious male and female rats to multiple i.v. injections of 1 μg human (h) GRF1-29NH2. The peak GH responses occurred 3–5 min after hGRF1-29NH2 injection and were lower in female than in male rats. Both males and females responded uniformly to hGRF1-29NH2 injections given 180 min apart and the GH responses became entrained with no endogenous GH pulsing. Female rats produced consistent GH peaks in response to hGRF1-29NH2 injections at 90-min intervals, whereas male rats responded only to alternate injections, so that GH peaks occurred only every 180 min despite giving GRF every 90 min. When the frequency of hGRF1-29NH2 administration was increased to once every 40 min female rats again responded consistently to each injection. Male rats responded intermittently, being able to respond to two injections 40 min apart, after which they became refractory to hGRF1-29NH2. This cycle of varying sensitivity to GRF in male rats probably underlies their 3-hourly endogenous GH secretory rhythm. Female rats can respond uniformly to repeated GRF injections, consistent with their more continuous pattern of endogenous GH secretion. Introducing a pulse of 10 μg rat GH into a series of hGRF1-29NH2 injections did not induce refractoriness to hGRF1-29NH2, suggesting that GH does not itself desensitize the pituitary to GRF. Whether the different patterns of GH secretion in males and females result from different patterns of GRF and/or somatostatin secretion remains to be determined. J. Endocr. (1985) 106, 281–289

scholarly journals Effects of Growth Hormone Secretagogues on Prolactin Release in Anesthetized Dwarf (dw/dw) Rats*

Endocrinology ◽  
1998 ◽  
Vol 139 (8) ◽  
pp. 3590-3596 ◽  
Author(s):  
Danielle F. Carmignac ◽  
Pamela A. Bennett ◽  
Iain C. A. F. Robinson
Keyword(s):  
Growth Hormone ◽  
Receptor Expression ◽  
Female Rats ◽  
Normal Male ◽  
Growth Hormone Secretagogues ◽  
Prolactin Release ◽  
Male And Female ◽  
Gh Secretagogues ◽  
Male And Female Rats ◽  
Tsh Levels

Abstract In addition to stimulating GH release, GH secretagogues such as GH-releasing peptide-6 (GHRP-6) stimulate small amounts of ACTH and PRL release. Although the effects on ACTH have recently been studied, there is little information about the effects of GHRP-6 on PRL. We have now studied GHRP-6-induced GH and PRL release and their regulation by estrogen (E2) in anesthetized male and female rats and in GH-deficient dwarf (dw/dw) rats that maintain high pituitary PRL stores and show elevated hypothalamic GH secretagogue receptor expression. Whereas GHRP-6 (0.1–2.5 μg, iv) did not induce PRL release in normal male or female rats, significant PRL responses were observed in dw/dw females. These responses were abolished by ovariectomy and could be strongly induced in male dw/dw rats by E2 treatment. These effects could be dissociated from GHRP-6-induced GH release in the same animals, but not from PRL release induced by TRH, which was also abolished by ovariectomy and induced in males by E2 treatment. However, the effects of GHRP-6 on PRL were unlikely to be mediated by TRH because in the same animals, TSH levels were unaffected by GHRP-6 whereas they were increased by TRH. The increased PRL response could reflect an increase in GH secretagogue receptor expression that was observed in the arcuate and ventromedial nuclei of E2-treated rats. Our results suggest that the minimal PRL-releasing activity of GHRP-6 in normal rats becomes prominent in GH-deficient female dw/dw rats and is probably exerted directly at the pituitary; these GHRP-6 actions may be modulated by E2 at both hypothalamic and pituitary sites.

Growth Hormone Secretion Is Differently Affected in Genetically Obese Male and Female Rats

1993 ◽  
Vol 57 (5) ◽  
pp. 928-934 ◽  
Author(s):  
Daniela Cocchi ◽  
Marco Parenti ◽  
Lorena Cattaneo ◽  
V. De Gennaro Colonna ◽  
Andrea Zocchetti ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Female Rats ◽  
Male And Female ◽  
Male And Female Rats ◽  
Obese Male

SOME BIOLOGICAL PROPERTIES OF A POTENT FOLLICLE STIMULATING HORMONE PREPARATION

1965 ◽  
Vol 48 (3) ◽  
pp. 439-445 ◽  
Author(s):  
Harold Papkoff
Keyword(s):  
Interstitial Cell ◽  
Follicle Stimulating Hormone ◽  
Intrinsic Property ◽  
Biological Properties ◽  
Female Rats ◽  
Male And Female ◽  
Male And Female Rats ◽  
Stimulating Hormone

ABSTRACT A preparation of ovine follicle stimulating hormone (FSH) which is approximately 50 times as active as NIH-FSH-S1 has been tested in hypophysectomized male and female rats and found to be a potent steroidogenic factor. Contamination of the FSH preparation with interstitial cell-stimulating hormone (ICSH, LH) was found to be very low (0.006–0.016 unit/mg) and could not account for the observed activity. In addition, treatment of the FSH preparation with 6 m urea and neuraminidase indicates that the steroidogenic activity is either an intrinsic property of the FSH molecule or a discrete entity which differs chemically from ICSH.

Significance of the Secretory Pattern of Growth Hormone

Physiology ◽  
1986 ◽  
Vol 1 (2) ◽  
pp. 44-47
Author(s):  
OGP Isakkson ◽  
J-O Jansson ◽  
RG Clark ◽  
I Robinson
Keyword(s):  
Growth Hormone ◽  
Plasma Concentration ◽  
High Amplitude ◽  
Female Rats ◽  
Healthy Children ◽  
Male And Female ◽  
Male And Female Rats ◽  
Low Concentrations ◽  
Lower Amplitude ◽  
Secretory Pattern

The plasma concentration of growth hormone fluctuates widely with pronounced peaks at intervals of a few hours and troughs of nearly vanishingly low concentrations in between. The pattern of secretion varies, and different patterns affect growth differently. Tall children usually have frequent growth hormone peaks of a high amplitude, whereas short, healthy children usually have fewer peaks of a lower amplitude. Male and female rats have different patterns, and a "masculine" pattern promotes growth more than a "feminine" pattern. If the same amount of growth hormone is administered in several pulses rather than continuously, the effect on growth is much greater.

PREVENTION OF CENTRAL DEFEMINIZATION BUT NOT MASCULINIZATION IN MALE RATS BY INHIBITION NEONATALLY OF OESTROGEN BIOSYNTHESIS

1977 ◽  
Vol 74 (3) ◽  
pp. 375-382 ◽  
Author(s):  
J. T. M. VREEBURG ◽  
PAULA D. M. VAN DER VAART ◽  
P. VAN DER SCHOOT
Keyword(s):  
Sexual Function ◽  
Ovarian Function ◽  
Testosterone Propionate ◽  
Neonatal Period ◽  
Female Rats ◽  
Male Rats ◽  
Normal Male ◽  
Male And Female ◽  
Male And Female Rats ◽  
Copulatory Behaviour

SUMMARY An inhibitor of aromatization, androsta-1,4,6-triene-3,17-dione (ATD), was administered to newborn male and female rats and various parameters of gonadal and sexual function were examined in adulthood. Males injected with 1 mg ATD on the day of birth (day 1) and on days 3, 5, 10 and 15 postnatally, subsequently (day 55) showed normal male and female copulatory behaviour, but were not able to maintain cyclicity in ovarian transplants. When the ATD was administered by Silastic implants, however, cyclicity in ovarian transplants did occur. Neither form of treatment brought about significant changes in neonatal plasma or testicular testosterone concentrations. Female rats implanted on day 3 of life with Silastic capsules containing ATD and then given an injection of 0·25 mg testosterone propionate on day 5 subsequently showed normal ovarian function, whereas the controls receiving only testosterone propionate showed persistent vaginal cornification, anovulation and polyfollicular ovaries. The results support the view that the central conversion of testicular androgens to oestrogens during the neonatal period is necessary to abolish cyclic gonadotrophin release and to suppress female copulatory behaviour.

FAILURE OF DIHYDROTESTOSTERONE TO ELICIT SEXUAL BEHAVIOUR IN THE FEMALE CAT

1977 ◽  
Vol 75 (1) ◽  
pp. 173-174 ◽  
Author(s):  
VERONICA A. CERNY
Keyword(s):  
Sexual Behaviour ◽  
Female Rats ◽  
University Of Pennsylvania ◽  
Male Rat ◽  
Peripheral Target ◽  
Target Tissue ◽  
Male And Female ◽  
Behavioural Effects ◽  
Male And Female Rats ◽  
Target Organs

Laboratory of Anatomy, Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, U.S.A. (Received 28 March 1977) Testosterones have stimulatory effects on peripheral target tissue and sexual behaviour in male and female rats (Beach, 1942), guinea-pigs (Young, 1961; Diamond & Young, 1963), rabbits (Palka & Sawyer, 1966; Beyer & Rivaud, 1973) and cats (Green, Clemente & de Groot, 1957; Young, 1961; Whalen & Hardy, 1970). 5α-Androstan-17β-ol-3-one (dihydrotestosterone, DHT) has stimulatory effects on peripheral target organs, and like testosterones, a negative feedback effect on the pituitary gland and hypothalamus (Feder, 1971). No behavioural effects were seen in male or female rats when DHT was injected systemically (Beyer, Morali & Cruz, 1971; Feder, 1971) nor in the male rat when it was administered intracerebrally (Johnston & Davidson, 1972). Many experiments support the hypothesis that only androgens that can be aromatized to oestrogens can elicit sexual behaviour and

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