摘要:

The effects of treatment for 5 or 9 days with varying doses of thyrotropin-releasing hormone (TRH) or the linear β-alanine TRH congener (pGlu-His-Pro-β-Ala-NH2) on serum levels of TSH, T3 and T4 were studied in mice and rats. At low doses in rats treatment with TRH for 9 days significantly increased serum levels of T3 but not serum T4 whereas a higher dose of TRH (10 mg/kg) reduced serum T3 levels. β-ALA TRH (0.1–10 mg/kg IP) treatment for 9 days in rats significantly reduced serum T4 levels whereas serum T3 levels were only depressed at higher doses (1–10 mg/kg IP) of the peptide. In mice treatment for 5 days with TRH (1 and 10 mg/kg IP) significantly reduced serum levels of T3 and T4. In addition, TRH (0.1–10 mg/kg IP) or β-ALA·TRH treatment (1.0–10 mg/kg IP) for 9 days significantly reduced serum TSH levels in rats. TRH (10 mg/kg IP for 9 days) also significantly reduced serum GH levels in rats. No alteration in hypothalamic content of TRH or LHRH was observed after chronic TRH treatment. Some, but not all, of our findings support the hypothesis that treatment with high doses of TRH reduce pituitary-thyroid axis functions by a direct effect on hypophysial T

ISSN:0028-3835    

DOI:10.1159/000123000

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Both luteinizing hormone-releasing hormone (LHRH) and thyrotropin-releasing hormone (TRH) induce sexual receptivity in ovariectomized, estrogen-primed female lizards (Anolis carolinensis). Ovariectomized females pretreated with three daily injections of a subthreshold dose (0.2 μg) of estradiol benzoate were administered either 500, 1,000 or 1,500 ng of LHRH, or 1,000 ng of TRH 48 h following the last estrogen pretreatment injection. Hormone-treated females exhibited significantly higher sexual receptivity scores than controls when tested 2, 4, 6 and 24 h post-injection. Female sexual receptivity scores in females that were administered 500 ng of LHRH or 1,000 ng of deamido TRH were, however, no different than control scores at these test times. The observed ability of LHRH to increase female sexual receptivity is consistent with previous results in birds and mammals. The ability of TRH to increase female sexual receptivity is a novel finding that may underscore differences in neuroendocrine regulation of vertebrate estrous behavior

ISSN:0028-3835    

DOI:10.1159/000123001

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Constant intraventricular infusion (3.3–6.6 μl/min) of artificial cerebrospinal fluid with sodium concentrations of 100, 150, 200, 250, 300, and 350 mM produced a linear dose-related change in renal sodium excretion in conscious, unrestrained Sprague-Dawley rats. The periventricular receptors stimulated were able to evoke substantial changes in body sodium balance; the 350 mM Na CSF produced an estimated 14% deficit in the content of Na in the extracellular fluid over a 5-hour infusion period. This is the first demonstration of such a dose-response relation over a wide range of CSF Na concentration (above and below normal) in conscious animals. Both the dose-response relation, and the magnitude of the effects, suggests an important physiologic role for this control mechanism. The natriuresis in response to 300 mM sodium infusion was identical in Long-Evans Brattleboro rats heterozygous for diabetes inspidus (Dl), and in Sprague-Dawley rats, but was completely absent in homozygous animals. Although the experimental methods (conscious unrestrained rats) precluded simultaneous evaluation of efferent pathways other than antidiuretic hormone (ADH), the evidence from the DI rats suggests that ADH may be the efferent pathway for the respon

ISSN:0028-3835    

DOI:10.1159/000123002

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The purpose of this experiment was to trace the development of animals treated with exogenous corticosterone in order to determine whether maturation progressed more slowly but in a continuous fashion or whether the animals experienced a temporary cessation of development (`pubertal diapause’) during the prepubertal period. Daily administration of corticosterone in the drinking water (160 µg/mJ 4% ethanol in tap water: B-treated) from 22 days of age produced a significant delay in both vaginal opening and ovulation while 4% ethanol (the vehicle for B) or 16 µg B in ethanol was compatible with normal puberty. At 32 days of age, body weights, ovarian and uterine weights were comparable in controls, ethanol-treated and B-treated rats but adrenal weights were depressed by 160 µg B. Puberty progressed normally in ethanol-treated and 16 µg B-treated rats and organ weights were comparable in these groups on days 36 and 40. At these times, all organ weights in rats treated with 160 µ% B remained at levels comparable to day 32. A significant increase in organ weight took place only at puberty onset around 45 days of age. In contrast to other groups, puberty was not associated with adrenal growth in 160 µg B-treated rats. Estradiol, progesterone and prolactin levels remained level and similar to values found on day 32 in 160 µg B-treated rats until they entered puberty. No significant differences in FSH and LH were found among the groups. It can be concluded that rats maintained on a high dose of corticosterone passed through a waiting period during which very little growth or increased steroid secretion occurred and that they escaped from this ‘pubertal diapause’ as puberty began, despite the absence of recovery of adre

ISSN:0028-3835    

DOI:10.1159/000123003

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Intrahypothalamic implants of testosterone propionate (TP), 5α-dihydrotestosterone (DHT) and estradiol (E) were compared for their effectiveness in reactivating sexual behavior of castrated male golden hamsters. Males tested preexperimentally and then observed for loss of sexual behavior responses after long-term castration were divided into four experimental treatment groups: anterior TP implants, DHT implants and E implants, and posterior TP implants. All animals were tested at 7 and 21 days postimplantation. On the day 7 implant test mount frequency, latency and duration per mount were significantly different from the castrate response for the TP implant groups. On the day 21 implant test both TP and E implant groups showed significant changes in mounting while intromission frequency, latency and duration per intromission were significantly different from the castrate only for the TP implant groups. DHT implants were not effective in reactivating any aspect of copulatory behavior in the castrate male hamster

ISSN:0028-3835    

DOI:10.1159/000123004

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

Using two tests in intact adult rats, it has been found that a high positive correlation exists (p < 0.005) between the ovulation inhibiting and the serotonin antagonistic activities measured in vivo of five tricyclic compounds and ten ergot derivatives. In these chemically different classes of compounds, certain structural modifications induced similar activity changes in both tests. These pharmacological results support the view that serotonin plays an essential, apparently facilitatory role in the central mechanisms controlling ovulation in the rat.

ISSN:0028-3835    

DOI:10.1159/000123005

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The changes in the nucleus preopticus (NPO) and nucleus lateralis tuberis (NLT) of the catfish. Clarias batrachus, were studied after electrical stimulation of the optic nerve. The aldehyde fuchsia (AF)-positive neurosecretory material from the entire NPO was depleted after a 10-min stimulation as revealed from the bulk-stained preparations and tissue sections. However, a 3-min stimulation was sufficient to cause significant hypertrophic changes in the neuronal nuclei (p<0.005 in the ventral neurons; p < 0.01 in the dorsal neurons). In order to evoke significant stimulatory changes in the cell nuclei of the NLT, a longer period of stimulation than that for the NPO was essential. Similarly, stimulations of different durations were required to induce significant hypertrophic changes in the pars anterior and pars posterior of the NLT. Based on these observations, the possible existence of an afferent pathway from the optic nerve to the hypothalamic neurosecretory nuclei is suggested.

ISSN:0028-3835    

DOI:10.1159/000123006

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

The effect of stimulation of the bed nucleus of the stria terminalis (BNST) on ovulation and LH release was studied in unanesthetized, freely moving rats. Electrochemical stimulation (anodic d.c, 100 µA/30 sec) was applied at i 1.30 h through chronically implanted monopolar, stainless steel electrodes. Serial blood samples were obtained by way of a plastic cannula implanted in the jugular vein. Stimulation on the day of proestrus prevented ovulation and the preovulatory discharge of LH when the stimulus was applied to the lateral part of the BNST but advanced the surge of LH in those rats stimulated in the medial part of the nucleus. In ovariectomized estrogen-primed rats stimulation in the medial part of the BNST produced LH release but no effect was seen when the stimulus was applied in the lateral part. It is concluded that the BNST is part of a dual system with antagonistic effects on LH secretion

ISSN:0028-3835    

DOI:10.1159/000123007

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

A nonstressful frequent sampling technique was employed to determine the effect of perphenazine, 5 mg/kg on spontaneous secretion of rat growth hormone (rGH). The drug blocked secretion almost entirely for at least 3, but no more than 22 h. These results suggest a role for dopamine and/or norepinephrine as stimulatory neurotransmitters for spontaneous rGH secretory episodes. They further suggest that experimental or therapeutic use of phenothiazines might produce functional GH deficiency.

ISSN:0028-3835    

DOI:10.1159/000123008

出版商:S. Karger AG    

年代:1980

数据来源: Karger

摘要:

In ovariectomized rhesus monkeys (Macaco mulatto) electrical stimulation (ES) of the medial basal hypothalamus (MBH) for 30 min with stimulus parameters that caused no overt behavioral responses elicited 7-fold and 2-fold increases in serum concentrations of prolactin (Prl) and luteinizing hormone (LH), respectively, 15–30 min after the onset of ES. Intravenous infusion of dopamine (5, 10, or 40, µg/kg body weight/min) for 1 h beginning 30 min before ES markedly reduced (5- and 10-µg doses, p < 0.05) or inhibited (40-µg dose, p < 0.01) the electrically induced rise in serum Prl. Infusion of apomorphine, a drug that stimulates dopamine receptors, also suppressed or abolished the electrically induced elevation in serum Prl at doses of 100 and 150 µ 0.05). Moreover, the 40-µg of the endogenous opiate, β-endorphin, also elicited an increase in serum Prl to more than preinject¡on levels (p < 0.05). Infusion of naloxone · HCl (an opiate antagonist) at a dose of 10/fg/kg b.w./min for 50 min blocked the rise in serum Prl after the injection of β-endrophin. Naloxone infusion at 10 and 20 µ 0.05). However, these same naloxone regimens markedly reduced the rise in serum Prl after ES of the lostral hypothalamus (p < 0.01). Thus, within the MBH-pituitary unit of the rhesus monkey, dopamine appears to play a role in the electrically induced release of Prl. but not of LH. Although β-endorphin can initiate release of Prl, its locus of action, unlike that of dopamine, appears to be somewhere above the MBH-pituitary axis and may involve rostral hypothal

ISSN:0028-3835    

DOI:10.1159/000123009

出版商:S. Karger AG    

年代:1980

数据来源: Karger