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Results for “PITUITARY HORMONES”

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At least 919 records · Page 51Linked to original sources
PubMed1977

Effect of acute exposure to cold on the levels of corticosterone and pituitary hormones in plasma collected from free conscious cannulated rats.

To investigate the initial response of the pituitary and adrenal cortex functionings of rats acutely exposed to cold, we developed a technique for cannulation which allowed sequential blood collection from conscious and freed rats. Two cannulae were inserted, one into the carotid artery used for collection and the other into the femoral vein for blood transfusion to keep the blood volume constant. Significant increases in plasma corticosterone and thyrotropin were evoked within 15 min after exposure. While plasma growth hormone (GH) slightly decreased, and the prolactin level tended to fall by 1 hr after cold exposure but the difference was not significant as compared with control values.

Animals↗
PubMed1995

[Effect of ovariectomy and natural menopause on levels of selected pituitary hormones, 17-beta estradiol and lipid profile in blood serum].

UNLABELLED: The main goal of this study was to measure changes in pituitary and sex hormone levels as a result of surgical or natural menopause, assess influences and correlation's between concentration of hormones and selected parameters of lipid profile important in the atherogenesis in the early period after surgical ovariectomy and during natural menopause. The first group consisted of 59 women (age +/- 3, 7) on whom hysterectomy with bilateral ovariectomy were performed. Blood samples were taken before operation and on 9th day after the operation. The second group consisted of 28 postmenopausal women (age 53 +/- 4). Methods hormonal measures were performed by radioimmunometric assays in blood serum (FSH, LH, PRL, 17-beta estradiol, testosterone, androstenedione and SHGB). The assessment of particular parameters of lipid profile: total cholesterol, HDL-C, LDL-C and triglycerides was performed by biochemical methods. RESULTS: We found statistically important, negative correlation between levels of estradiol and gonadotrophins; after surgical ovariectomy and natural menopause there are time depended changes in lipid profile. Early period after surgical ovariectomy is characterized by decrease in concentration of 17-beta estradiol and increase of atherogenic lipid parameters. Among postmenopausal women there is negative correlation between 17-beta estradiol concentration and atherogenic factor and total cholesterol. Changes of the lipid profile in the serum of the blood may be connected with hormonal homeostatic disturbances, decreased level of oestrogen's and rising level of gonadotrophins.

Estradiol↗
PubMed1975

Plasma hormones and pituitary luteinizing hormone in the rat during the early stages of pregnancy and after post-coital treatment with tamoxifen (ICI 46,474).

Plasma levels of oestradiol-17beta, progesterone and luteinizing hormone (LH) and pituitary levels of LH have been measured during the first 6 days of pregnancy, in normal rats and in rats receiving two doses of Tamoxifen (trans-1-(rho-beta dimethylamino-ethoxyphenyl)-1-2-diphenylbut-1-ene) on day 2 of pregnancy. In normal rats oestradiol rose strongly from early on day 3 to reach a peak concentration between 22.00 h on day 3 and 08.00 h on day 4. Progesterone concentrations rose from day 2 to reach peak values on day 3-4. In animals in which implantation was delayed 20-24 h by administration of Tamoxifen (0.1 mg/kg) orally on day 2 the increased level of plasma oestrogen was also delayed by 20 h. A higher dose of Tamoxifen (0.2 mg/kg) on day 2, which prevented implantation, completely eliminated the increase in plasma oestradiol. Neither dose of Tamoxifen affected the levels of progesterone. In both normal rats and rats treated with 0.1 mg Tamoxifen/kg, plasma LH levels declined by day 3 while pituitary levels rose steadily. There was no detectable change in either plasma or pituitary LH levels, accompanying the increase in plasma oestradiol in the normal rats. In animals receiving Tamoxifen (0.2 mg/kg), plasma LH increased to a maximum by day 4 while levels of pituitary LH decreased. The results show that the oestrogen "surge" of early pregnancy, occurs normally about midnight on day 3 and not late on day 4 as previously thought. It is considered that the plasma oestradiol peak in early pregnancy results from an increased release of FSH rather than an increased release of LH. Tamoxifen may owe part of its antifertility action to a capacity to inhibit the synthesis of oestradiol from progesterone.

Adrenalectomy↗
PubMed1980

Immunocytochemical demonstration of anterior pituitary hormones in the pars tuberalis of long-term hypophysectomized rats.

The hormone-containing cells of the pars tuberalis of the rat adenohypophysis were studied, 4--5 months after hypophysectomy, with a double bridge immunocytochemical technique and with antisera directed against the hormones of the pars distalis. Corticotropes, lactotropes, somatotropes, thyrotropes, and gonadotropes were found in the pars tuberalis of all animals. These cells are well well situated to receive blood, nerve terminals, and tanycyte processes from the median eminence and, thus, to be influenced by the chemical messengers from the hypothalamus. It is concluded that the pars tuberalis has to be regarded as a potential source of adenohypophyseal hormones in an animal model traditionally considered to be free of such hormones.

Adrenocorticotropic Hormone↗
PubMed1993

N-methyl-d,l-aspartate modulation of pituitary hormone secretion in the pig: role of opioid peptides.

Sixteen ovariectomized (OVX) mature gilts, averaging 139.6 +/- 3.1 kg body weight (BW) were assigned randomly to receive either progesterone (P, 0.85 mg/kg BW, n = 8), or corn oil vehicle (OIL, n = 8) injections im twice daily for 10 d. On the day of experiment, all gilts received either the EAA agonist, N-methyl-d,l-aspartate (NMA; 10 mg/kg BW, iv) alone or NMA plus the EOP antagonist, naloxone (NAL, 1 mg/kg BW, iv), resulting in the following groups of 4 gilts each: OIL-NMA, OIL-NMA-NAL, P-NMA and P-NMA-NAL. Blood samples were collected via jugular cannula every 15 min for 6 hr. All pigs received NMA 5 min following pretreatment with either 0.9% saline or NAL 2 hr after blood collection began and a GnRH challenge 3 hr after NMA. Administration of NMA suppressed (P < 0.03) LH secretion in OIL-NMA gilts and treatment with NAL failed to reverse the suppressive effect of NMA on LH secretion in OIL-NMA-NAL gilts. Similar to OIL-NMA gilts, NMA decreased (P < 0.03) mean serum LH concentrations in P-NMA gilts. However, in P-NMA-NAL gilts, serum LH concentrations were not changed following treatment. All gilts responded to GnRH with increased (P < 0.01) LH secretion. Additionally, administration of NMA increased (P < 0.01) growth hormone (GH) and prolactin (PRL) secretion in both OIL-NMA and P-NMA gilts, but this increase in GH and PRL secretion was attenuated (P < 0.01) by pretreatment with NAL in OIL-NMA-NAL and P-NMA-NAL gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1985

Effect of acute ether stress on monoamine metabolism in median eminence and discrete hypothalamic nuclei of the rat brain and on anterior pituitary hormone secretion.

This study was designed to correlate the endocrine responses elicited by acute ether stress with the changes in metabolism of several monoamines in discrete nuclei of the rat brain. Concentrations of norepinephrine (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) and also of the specific metabolites of NE, DA, and 5-HT, 3-methoxy-4-hydroxyphenylethylene glycol, 3,4-dihydroxyphenylacetic acid, and 5-hydroxyindole-3-acetic acid, respectively, were concurrently measured in microdissected nuclei using high-performance liquid chromatography with electrochemical detection. The ratio of the metabolites to their respective amines was used as an estimate of the metabolism of NE, DA, and 5-HT. Acute exposure to ether vapors induced, within 5-15 min, large increments in plasma levels of adrenocorticotropic hormone (ACTH), beta-endorphin, and prolactin (PRL), and decrements in the levels of plasma growth hormone (GH). Significant increases in NE metabolism were observed in the rostral (ANr) and caudal (ANc) divisions of the arcuate nucleus, as well as in the paraventricular (PVN) and dorsomedial nuclei, 15 min after ether stress. A significant decrease in 5-HT metabolism was observed in the PVN, supraoptic nucleus, and ANc, whereas significant increases in 5-HT metabolism were detected in the suprachiasmatic nucleus and ANr. DA metabolism selectively increased in the ANr. The present results indicate that the acute changes in ACTH, beta-endorphin, PRL, and GH release induced by ether exposure are temporally correlated with increases in NE metabolism in many hypothalamic nuclei; a selective increase in DA metabolism restricted to the ANr, and differential effects on 5-HT metabolism, probably reflecting selective activation or inhibition of different populations of 5-HT neurons.

Adrenocorticotropic Hormone↗
PubMed1989

Action of trimipramine on sleep and pituitary hormone secretion.

Trimipramine is unlike other antidepressants in that it does not suppress REM sleep and possesses an atypical pharmacological profile. This antidepressant was administered in the evening to 10 depressed patients at a dosage of 75 mg on night 1 with 25 mg increments each night, up to 200 mg on night 6 and at this dosage thereafter. Sleep parameters were measured at baseline and on nights 2, 11 and 21. On nights 11 and 21, there was a significantly improved sleep pattern as shown by increases in sleep period time, total sleep time and sleep efficiency, and there was a decrease in sleep onset latency. No suppression of REM sleep occurred, and an increase was even noted; this, however, may have been due to a particularly low baseline value. Subjective assessments in which self-ratings of sleep quality were used also demonstrated an improvement in sleep. In addition, the neuroendocrine effects of trimipramine were investigated in 8 healthy volunteers after a single oral 75 mg dose. After 3 hours, a significant fall in plasma cortisol concentration from 117 to 43 micrograms/L and a significant rise in plasma prolactin concentration from 6 to 16.3 micrograms/L were observed, but there was no significant effect on plasma human growth hormone concentration. These results further support the effectiveness of trimipramine therapy in normalising a disturbed sleep pattern in depressed patients, and it may be of use in non-depressed insomniacs. The acute neuroendocrine effects of trimipramine are similar to those observed with neuroleptics and further indicate its atypical pharmacological profile.

Adult↗
PubMed1991

[Effects of continuous lighting on secretion of melatonin and pituitary hormones in women].

Effects of light exposure on the serum concentrations of melatonin, prolactin, LH and FSH were studied in 53 women during their follicular phases. Twenty seven women were exposed to light (500-800 lux at eye level) from 17:30h to 22:00h, and 17 women received the same light intensity from 17:30h to 2:00h, while 9 women stayed in a dark room from 21:00h to 2:00h as control subjects. The light exposure suppressed a nocturnal increase in the serum concentrations of melatonin both at 22:00h and 2:00h. The light exposure and awake condition suppressed the serum prolactin concentrations and increased the serum FSH concentrations at 2:00h, while the influence on the serum LH concentrations was not clear because of LH pulsatility. These results show that the circadian rhythm of melatonin, prolactin and FSH is affected by light exposure and wakefulness, and the effects of light exposure would become more evident if light exposure was continued over a longer period.

Adult↗