Seasonal Fluctuations in Pituitary Gland and Plasma Levels of Gonadotropic Hormones inRana

1998 ◽  
Vol 109 (1) ◽  
pp. 13-23 ◽  
Author(s):  
Jung W. Kim ◽  
Wook-Bin Im ◽  
Han H. Choi ◽  
S. Ishii ◽  
Hyuk B. Kwon
Keyword(s):  
Pituitary Gland ◽  
Plasma Levels ◽  
Seasonal Fluctuations ◽  
Gonadotropic Hormones

Effect of corticosterone on the hypothalamic-pituitary-gonadal system of male Japanese quail exposed to either short or long photoperiods

1982 ◽  
Vol 95 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Pierre Deviche ◽  
Renato Massa ◽  
Luciana Bottoni ◽  
Jean-Claude Hendrick
Keyword(s):  
Pituitary Gland ◽  
Japanese Quail ◽  
Plasma Levels ◽  
Posterior Hypothalamus ◽  
Daily Dose ◽  
Cloacal Gland

Male quail were bred under short photoperiods of 8 h light: 16 h darkness (8L : 16D; SD) for the first 4 weeks of life and were then transferred to either long photoperiods of 16L : 8D (LD) or maintained under the SD regime. Both groups of birds were treated for 2 weeks with a daily dose of either 0·25 or 1·0 mg corticosterone. The conversion of [14C]testosterone in vitro into 5α- and 5β-dihydrotestosterone (5α- and 5β-DHT), 5α- and 5β-androstane-3α,17β-diol, and androstenedione was then measured in the pituitary and cloacal glands of all birds. In the hyperstriatum and posterior hypothalamus only 5β-reduced metabolites and androstenedione were detected. Transfer to LD and injection of corticosterone affected the metabolism of testosterone only in the pituitary and cloacal glands. In the pituitary gland, exposure to LD increased the production of 5α-reduced metabolites but not of either 5β-reduced metabolites or androstenedione. In both SD and LD birds, injections of corticosterone enhanced the production of 5β-reduced steroids and decreased the production of androstenedione. In LD birds corticosterone also decreased the production of 5α-androstane-3α,17β-diol. Plasma levels of LH and FSH were higher in the LD than in the SD birds. In the SD birds treatment with corticosterone increased the level of LH after 14 days of treatment. Exposure to LD decreased the production of 5β-androstane-3α,17β-diol and androstenedione in the cloacal gland and increased the conversion of testosterone into 5α-DHT Treatment with corticosterone increased the production of androstenedione in the cloacal gland of LD birds but decreased it in that of SD birds. Corticosterone also partially blocked the photoinduced growth of the cloacal gland, but it slightly stimulated the growth of the gland in the SD birds. After 2 weeks of treatment SD (but not LD) corticosterone-treated birds had higher testicular weights than the corresponding controls. It is suggested that treatment with corticosterone might affect the hypothalamic-pituitary-gonadal axis partly through changes in the metabolism of testosterone.

CHANGES IN PLASMA LEVELS OF PROLACTIN AND LH INDUCED BY LUTEOLYTIC OR LUTEOTROPHIC TREATMENT IN INTACT CYCLING SHEEP AFTER SECTION OF THE PITUITARY STALK

1973 ◽  
Vol 73 (4) ◽  
pp. 625-634 ◽  
Author(s):  
G. Kann ◽  
R. Denamur
Keyword(s):  
Pituitary Gland ◽  
Plasma Levels ◽  
Limit Of Detection ◽  
Oestrous Cycle ◽  
The Other ◽  
Pituitary Stalk ◽  
Similar Treatment ◽  
Luteal Regression ◽  
Gonadotrophin Secretion ◽  
Major Increase

ABSTRACT Oestradiol has been shown to cause either premature luteal regression or prolonged luteal maintenance depending on whether it is administered early or late in the oestrous cycle. Although these effects are not observable in the absence of the uterus, it was considered desirable to examine the possibility that the pituitary gland as well as the uterus may be involved in this phenomenon. Accordingly, plasma LH and prolactin concentrations were studied in sheep treated with oestradiol from day 3 (luteotrophic action) or day 11 (luteolytic action) with and without pituitary stalk section. Plasma LH fell below the limit of detection (0.3 ng/ml) in the plasma of sheep after pituitary stalk section, whether or not oestradiol had been administered. In the intact ewe, oestradiol given from day 3 resulted in luteal maintenance associated with a significant increase in the secretion of plasma LH and prolactin. However, similar treatment in the stalk sectioned ewe also resulted in luteal maintenance without any major increase in gonadotrophin secretion. On the other hand, when oestradiol was given from day 11, there was no evidence either from the intact or the stalk sectioned sheep that the pituitary contributed to the luteolytic action of oestradiol may possibly have a pituitary component, the luteolytic action is probably mediated solely by the oestrogenic action on the uterus.

Effect of stress on tissue and plasma levels of immunoreactive β-endorphin in ovariectomized rats primed with oestrogen and progesterone

1984 ◽  
Vol 100 (3) ◽  
pp. 277-280 ◽  
Author(s):  
G. K. Hulse ◽  
G. J. Coleman
Keyword(s):  
Pituitary Gland ◽  
Plasma Levels ◽  
Anterior Pituitary ◽  
Sesame Oil ◽  
Anterior Pituitary Gland ◽  
Oestrous Cycle ◽  
Ovariectomized Rats ◽  
Neurointermediate Lobe ◽  
Pituitary Tissue

ABSTRACT The aim of this study was to investigate the effect of oestrogen and progesterone on levels of immunoreactive β-endorphin (Ir-β-EP) in the hypothalamus, anterior pituitary gland, neurointermediate lobe and plasma under normal conditions and conditions of stress. The injection of oestrogen + progesterone into ovariectomized rats increased Ir-β-EP levels in extracts of anterior pituitary tissue and in plasma, under both normal and stressed conditions. Exposure to a stress reduced the content of anterior pituitary Ir-β-EP in ovariectomized rats treated with oestrogen + progesterone and also with sesame oil. Such treatment only resulted in increments in plasma Ir-β-EP in oil-treated but not in oestrogen + progesterone-treated overiectomized rats. It was concluded (1) that oestrogen and progesterone are involved in the regulation of resting levels of anterior pituitary Ir-β-EP during the rat oestrous cycle, (2) that stress reduces levels of anterior pituitary Ir-β-EP and (3) that increased levels of plasma oestrogen + progesterone inhibit plasma Ir-β-EP increments which normally accompany exposure to stress. J. Endocr. (1984) 100, 277–280

Studies on Transplantations of Amphibian Anterior Pituitary into Chick Embryo. Analysis of Induction Capacity by Differential Solubility and Precipitation Method

Development ◽  
1963 ◽  
Vol 11 (1) ◽  
pp. 227-237
Author(s):  
Gajanan V. Sherbet
Keyword(s):  
Growth Hormone ◽  
Chick Embryo ◽  
Pituitary Gland ◽  
Ribonucleic Acid ◽  
Anterior Pituitary ◽  
Precipitation Method ◽  
Active Principle ◽  
Tissue Protein ◽  
Gonadotropic Hormones ◽  
Differential Solubility

Since the discovery by Bautzmann, Holtfreter, Spemann & Mangold (1932) that a diffusion of inducing substance takes place from the inductor into the competent reacting tissue, protein and ribonucleic acid have been favoured by candidates for the study of the nature of the inducing substance (see Brachet, 1960a, b). Recently Mangold, Tiedemann & Woellwarth (1956) studied the inductive capacity of ox anterior pituitary in gastrulae of Triton alpestris. It was found to have considerable inductive power. They suggested that the gonadotropic hormones or the growth hormone might be the active principle of induction. These hormones are glycoprotein or simple protein in nature and hence it was felt desirable to study the inductive capacity possessed by fresh anterior pituitary gland by resorting to differential solubility and precipitation of the various glycoprotein, protein and ribonucleic acid (RNA) constituents of the gland.

FURTHER STUDIES ON THE EFFECTIVENESS WITH WHICH EXOGENOUS LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE STIMULATE THE RELEASE OF ENDOGENOUS FOLLICLE-STIMULATING HORMONE DURING THE RAT OESTROUS CYCLE

1981 ◽  
Vol 88 (1) ◽  
pp. 103-113 ◽  
Author(s):  
O. A. ASHIRU ◽  
M. E. RUSH ◽  
C. A. BLAKE
Keyword(s):  
Luteinizing Hormone ◽  
Plasma Level ◽  
Pituitary Gland ◽  
Plasma Levels ◽  
Jugular Vein ◽  
Follicle Stimulating Hormone ◽  
Early Afternoon ◽  
Stimulation Of ◽  
Intact Rats ◽  
Stimulating Hormone

The effects of exogenous rat LH or FSH on the release of endogenous FSH in the cyclic rat have been investigated. Rats were administered phenobarbitone to block the spontaneous increases in gonadotrophins in plasma during pro-oestrus and oestrus and then cannulated through the jugular vein or cannulated and hypophysectomized during the late morning or early afternoon of pro-oestrus. Comparison of patterns of plasma FSH in hypophysectomized and intact rats after i.v. injection of 0·5 μg FSH at 17.00 h suggested that exogenous FSH stimulated the release of endogenous FSH in less than 5 h. Intravenous LH (2 μg at 16.00 and at 18.00 h) raised the level of FSH in plasma between 2 and 6 h after the first injection of LH. Both gonadotrophins stimulated FSH release by the pituitary gland during the morning of oestrus. Comparison of patterns of plasma FSH in hypophysectomized and intact rats after i.v. injection of 0·25 or 0·05 μg FSH at 14.00 h suggested that the latency between FSH injection and stimulation of some FSH release by the pituitary gland is as short as 2 h. Intravenous LH (3,4 or 9 μg) at 14.00 h did not increase the level of FSH in plasma within 2 h and was only minimally effective in raising the level within 4 h. Intravenous LH (2 μg at 16.00 and at 18.00 h) on the afternoon of dioestrus day 2 was nearly as effective in increasing the levels of FSH in plasma as it was when administered to pro-oestrous rats. This procedure did not raise the plasma levels of FSH in rats used on dioestrus day 1. The results suggest that in the phenobarbitone-blocked, pro-oestrous rat (1) a small increase (less than that observed spontaneously) in plasma rat FSH during pro-oestrus is effective in stimulating FSH release by the pituitary gland, (2) an increase in plasma rat FSH can exert positive feedback on its own secretion within 2 h and (3) a large increase in plasma rat LH is not very effective in increasing the plasma level of FSH over a period of 4 h. The results also suggest that the spontaneous increase in plasma levels of FSH and, to a lesser extent, of LH is involved in causing the selective phase of FSH release which occurs during late pro-oestrus and the morning of oestrus, and that LH and FSH act differently, but not necessarily by way of a different mechanism, to stimulate release of FSH by the pituitary gland.

Adrenocortical Activity in Hypophysectomized Dogs

1958 ◽  
Vol 193 (2) ◽  
pp. 403-407 ◽  
Author(s):  
Kristen Eik-Nes ◽  
Kenneth R. Brizzee
Keyword(s):  
Oral Administration ◽  
Pituitary Gland ◽  
Femoral Artery ◽  
Plasma Levels ◽  
Anterior Pituitary ◽  
Pituitary Function ◽  
Sodium Pentobarbital ◽  
Adrenal Hormones ◽  
Adrenocortical Activity ◽  
Sodium Pentobarbital Anesthesia

The pituitary gland was removed in normal mongrel dogs. Following this operation low or zero plasma levels of 17-hydroxycorticosteroids (17-OHCS) were seen as early as 12 hours postoperatively. Dogs completely hypophysectomized from 15 to 30 days exhibited no increase in plasma 17-OHCS subsequent to the ‘stress’ of sodium pentobarbital anesthesia and cannulation of the femoral artery, and adrenal venous levels of 17-OHCS were very low in hypophysectomized dogs subjected to the ‘stress’ of laparotomy. Between the 15th and 30th day following hypophysectomy a normal removal of intravenously administered cortisol was found. However, at this time after hypophysectomy an inferior response in plasma 17-OHCS was demonstrated following the intravenous administration of ACTH. The oral administration of adrenal hormones to normal dogs for 15 days led to a similar impairment in the responsiveness of adrenocortical tissue to ACTH injection. It has thus been shown that lack of pituitary function for 15–30 days will rapidly result in a functional atrophy of the canine adrenal cortex. The data further demonstrate that intravenously administered cortisol is removed or ‘utilized’ at a normal rate in animals lacking pituitary function. Small remnants of anterior pituitary tissue appear to maintain a reduced but measurable adrenocortical capacity in the dog.

THE EFFECT OF SYNTHETIC HYPOTHALAMIC RELEASING FACTORS ON PLASMA LEVELS OF LUTEINIZING HORMONE IN THE COCKEREL

1973 ◽  
Vol 59 (3) ◽  
pp. 495-502 ◽  
Author(s):  
B. J. A. FURR ◽  
G. I. ONUORA ◽  
ROSEMARY C. BONNEY ◽  
F. J. CUNNINGHAM
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Plasma Levels ◽  
Mammalian Species ◽  
Thyroid Stimulating Hormone ◽  
Releasing Factors ◽  
Stimulating Hormone

SUMMARY The capacity of synthetic luteinizing hormone releasing factor (LH-RF) to stimulate the release of luteinizing hormone (LH) from the pituitary gland of the cockerel has been examined. Administration of LH-RF to 21 intact and 12 castrated cockerels aged between 14 and 20 months resulted in a rapid increase in the levels of LH in the plasma within 5–10 min of injection in both groups of birds. Plasma LH then declined rapidly and returned to basal values within 1 h. The amount of LH released in the intact birds was dependent on the dose of LH-RF. Concentrations of LH in the plasma did not increase after injection of thyroid-stimulating hormone releasing factor but the response of the pituitary gland to a subsequent injection of LH-RF 2 h later was not altered. The pattern of release of LH in the cockerel is compared with that of some mammalian species.

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