摘要:

Intraperitoneal administration of 2-cyclooctyl-2-hydroxyethylamine (CONH; 25–75 mg/kg) produced dose-related reductions in the epinephrine (EPI) concentrations in both the hypothalamic and brainstem regions, but not in the adrenal glands. The reductions in the hypothalamic and brainstem EPI concentrations in rats anesthetized with pentobarbital sodium were accompanied by parallel increases in blood glucose. These data suggest that CONH induces its hyperglycemia action at least in part by altering central EPI biosynthesis. This hyperglycemic was antagonized by spinal transection or adrenalectomy, but not by vagotomy. This indicates that CONH increases the adrenal-sympathetic efferent activity and leads to hyperglycemia in rat

ISSN:0028-3835    

DOI:10.1159/000124175

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The effect of photoperiod on the rhythm in pineal N-acetyltransferase activity and on the growth of testes and of brown adipose tissue was studied in infant rats at the age of 5–15 days. After exposure to light at night, high N-acetyltransferase activity declined in 6-, 7-, and 8-day-old intact rats, but not in 5-day-old intact rats or in 8-day-old blinded rats. Hence, light might penetrate under closed eyelids and might be perceived by retinal photoreceptors in rats older than 6 days. In 15-day-old animals, the amplitude of the N-acetyltransferase rhythm was ten times higher than in 5-day-old rats. The pattern of the N-acetyltransferase rhythm, namely the duration of elevated nocturnal activity, was different under long and short photoperiod at least 1 week before opening of eyes. Photoperiod affected the growth of testes and of interscapular brown adipose tissue already in the preweaning period. In 15-day-old rats, immediately after opening of eyes, the weight of testes was significantly higher and the weight of brown fat lower under long than under short photoperiod. Photoperiodic regulation thus occurs before rats open their eyelid

ISSN:0028-3835    

DOI:10.1159/000124176

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Recent findings have shown that lesions of the hypothalamic paraventricular nuclei (PVN) disrupt the synthesis of melatonin in the rat pineal gland. In order to further clarify the role of the PVN in the control of pineal function, the effects of electrical stimulation of these nuclei were investigated in acutely blinded adult male Sprague-Dawley rats. Following electrical stimulation, pineal serotonin-N-acetyltransferase (NAT) activity and pineal melatonin content were measured by means of radioenzymatic and radioimmunoassay methods, respectively. Stimulation had no significant effect on pineal melatonin synthesis throughout the early part of the dark phase, but caused a significant reduction in NAT activity during the light phase and the latter part of the dark phase. The pineal melatonin content appeared reduced, but due to large individual variations this reduction was not statistically significant. Stimulation duration experiments reveal that reduction of NAT activity is time dependent, with significant inhibition occurring after 30 min of stimulation. These observations further support the involvement of the PVN in the melatonin rhythm generating pathway and suggest that electrical activation of fibers in the PVN is similar to the effects of light on pineal melatonin synthesis.

ISSN:0028-3835    

DOI:10.1159/000124177

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

A 24 amino acid polypeptide that does not originate from (pre)proenkephalin has been isolated from ovine adrenal chromaffin granules. Its sequence is: Arg-Leu-Pro-Gly-Glu-Leu-Arg-Asn-Tyr-Leu-Asp-Tyr-Gly-Glu-Glu-Val-Gly-Glu-Glu-Ala-Ala-Arg-Gly-Val. This peptide is generated from a precursor molecule that has also been purified and partially sequenced. The proteolytic cleavage occurs at a triple Arg site. A search of the available protein sequence data banks shows very little homology to any known protein.

ISSN:0028-3835    

DOI:10.1159/000124178

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The effect of bromocriptine (BEC) treatment on spontaneous, sparsely granulated, prolactin-producing pituitary adenomas was studied in aging female Long-Evans rats of at least 23 months of age. Rats treated with BEC for 1–44 days showed a marked decrease in serum prolactin (PRL) concentrations at the end of the treatment period (9.1–34 ng/ml) when compared to the serum PRL levels of age-matched control animals (94.6–233 ng/ml). No significant differences in serum PRL levels (ng/ml; mean ± SEM) were noted in rats withdrawn for 14 days from BEC treatment (132.9 ± 18.8) when compared to age-matched controls (181.5 ± 70.9). The mean pituitary weight (mg) was significantly reduced in the rats treated for 44 days with BEC (23.4 ± 1.4) compared to untreated controls (43.4 ± 8.3). At the time of sacrifice, PRL-producing adenomas were found in 16 of 33 control rats, 5 of 10 rats treated for 1 day with BEC, 5 of 20 rats treated with BEC for 44 days, and 12 of 28 rats in the animals withdrawn from BEC treatment for 14 days. Morphometric analysis of sparsely granulated PRL-containing adenomas revealed that, althought the nuclear area was reduced after 1 day of BEC treatment, the cytoplasmic area was reduced only after 44 days. Forming granule diameters were significantly increased after 44 days of BEC treatment and markedly decreased in the withdrawal group. Storage granule diameters were increased in both the 1-day and 44-day groups and were decreased in rats withdrawn from BEC for 14 days. Rough endoplasmic reticulum, forming granule, storage granule, and lysosome volume densities were increased after 1 day of BEC treatment. The Golgi region volume density decreased only after 44 days of BEC treatment. We conclude that aging female Long-Evans rats harboring PRL-producing pituitary adenomas can respond to BEC administration with a decrease in serum PRL levels and morphologic changes in adenoma cells. However, the structural alterations in PRL cells of the rat adenomas are less conspicuous than those of human tumors. In the rat, like in human patients, a direct toxic effect of BEC on PRL-producing adenoma cells has not been de

ISSN:0028-3835    

DOI:10.1159/000124179

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The push-pull cannula technique was used to evaluate the role of the medial preoptic/anterior hypothalamic area (MPO) in regulating pituitary luteinizing hormone (LH) and prolactin release. The concentrations of the three catecholamines – dopamine, norepinephrine (NE), epinephrine (E) – and gamma-aminobutyric acid (GABA) and glutamate could be measured in 15-min fractions at which interval blood samples for LH and prolactin determination were also collected. Comparison of neurotransmitter release rates into the MPO were made between ovariectomized and ovariectomized estradiol benzoate treated rats. Release of the neurotransmitters occurred in a pulsatile manner, the release episodes for each transmitter appeared to be independent of the others. No direct correlation between neurotransmitter release episodes and blood LH or prolactin levels could be established. The release of GABA was significantly lower and that of NE and E higher in ovariectomized animals in comparison to estrogen-primed ovariectomized animals under negative feedback conditions. In the afternoon, however, when the estrogen stimulated LH and prolactin release, preoptic GABA release was low, whereas preoptic NE and particularly E release rates were high. Conspicuously high dopamine and NE release episodes were observed in estrogen-primed animals at noon, i.e., prior to the expression of the positive feedback signal. This may reflect a biochemical correlate to the so-called critical period. No consistent differences between ovariectomized and ovariectomized estradiol-17β benzoate treated animals were observed for preoptic glutamate release rates. The data show that preoptic GABA release rates show generally an inverse pattern to NE and E release and therefore also to blood LH and prolactin levels. No direct mathematical correlation between any of the neurotransmitter release rates and blood hormone levels could be establi

ISSN:0028-3835    

DOI:10.1159/000124180

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

We have previously reported that luteinizing hormone releasing hormone (LH-RH) levels in the medial basal hypothalamus (MBH) of adult male rats castrated for 2 weeks can be raised by testosterone (T) or estradiol (E2) treatment for 3–4 days. The present study was undertaken to determine the time after castration when the hypothalamus becomes refractory to this feedback action and whether prolongation of exposure to steroids would reinstate the hypothalamic LH-RH response. Treatment with T (Silastic capsules, s.c.) for 4 days, when commenced either immediately or 14 days after castration, significantly raised the MBH LH-RH levels. A 4-day regimen of E2 or dihydrotestosterone, on the other hand, evoked similar increase when commenced up to 21–28 days after castration. Further delay in institution of the 4-day treatment rendered the three steroids completely ineffective. When the effects of prolongation of treatment were tested in long-term castrated rats (56 days), it was found that T required 14 days as compared to 7 days of exposure with E2 or dihydrotestosterone to produce an equivalent MBH LH-RH response. Furthermore, the MBH LH-RH and serum LH responses were not always correlated, since increments in the MBH LH-RH were observed when serum LH levels were suppressed by physiological levels of T or dihydrotestosterone and also when they were unchanged with low levels of T or E2. These studies show that long-term castration causes a dichotomy in responsiveness of the hypothalamo-pituitary axis to steroids. While LH secretion was readily suppressed by T after castration, the duration of T treatment to elevate the MBH LH-RH levels increased dramatically in long-term castrated rats. The suppression of LH release was not correlated with T-induced increments in the MBH LH

ISSN:0028-3835    

DOI:10.1159/000124188

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

We have compared the immunoreactive oxytocin neurophysin from the human pineal gland with human neurohypophyseal neurophysin. The two proteins were reduced and carboxymethylated with [14C]-iodoacetic acid. Since the pineal protein was available only in a very small amount, we were obliged to use [12C]-carboxymethyl apomyoglobin as a nonalkylatable carrier. The trypsin and subtilisin digests of the two labelled proteins were compared by high-voltage electrophoresis on paper, partition paper chromatography, and high-performance liquid chromatography. The distribution of radioactivity in the above peptide separations suggests a great similarity between the two proteins and few significant differences. As far as we are aware, this study is the first attempt to analyze an extrahypophyseal neurophysin at the molecular level.

ISSN:0028-3835    

DOI:10.1159/000124181

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Immunoreactive serotonin is demonstrated to be present in 75% of rat adrenal medullary cells using an antibody to serotonin and peroxidase-antiperoxidase immunocytochemical method. The concentration of serotonin in rat adrenals was found to be 7.7 ± 0.1 × 10–6 mol/kg wet weight by high-performance liquid chromatography with electrochemical detection. Drugs that block serotonin synthesis (p-chlorophenylalanine) or deplete biogenic amines (reserpine) diminish immunostaining. The serotonin precursor .L·tryptophan and pargyline, a monoamine oxidase inhibitor, augment staining in reserpine-depleted adrenals. Serotonin is localized in those medullary cells which contain phenylethanolamine-N-methyltransferase, an enzyme which is necessary for the synthesis of epinephrine. We conclude, therefore, that serotonin coexists with epinephrine in rat adrenal medullary chromaffin cells. These results suggest that the adrenal medulla may play a major role in the metabolism of serot

ISSN:0028-3835    

DOI:10.1159/000124182

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Protein profiles of brain areas mediating effects of steroid hormones on copulation were compared between animals in gonadal steroid states predictive of either the presence or absence of copulatory activity. A broad range of proteins present in micropunches of tissue from the medial preoptic area (MPO) and from the ventromedial hypothalamus (VMH) were compared between male and female rats with gonadal steroids present or absent. Half of the animals of each gender were gonadectomized 1 month prior to sacrifice. The remaining males were left intact, while the remaining females were gonadectomized, implanted with estrogen capsules, and injected with progesterone prior to sacrifice. These females were screened for sexual receptivity immediately prior to sacrifice. Proteins from the MPO and VMH of each animal were separated by two-dimensional gel electrophoresis, silver stained, and quantified by computerized optical densitometry. Several proteins differed in density between gels of high-steroid males and females and between high-steroid and absent-steroid animals of one or both genders. Two previously reported sex differences were replicated and found to depend on activational effects of gonadal steroids. Several interesting reversal patterns were noted between MPO and VMH, including three proteins that were affected by gonadectomy in the MPO of males, but not females, and in the VMH of females, but not males, thus correlating with sexual function. These included serum albumin (a possible index of local area blood flow) and neuron-specific enolase, a glycolytic enzyme of anaerobic metabolism. A probable genetic polymorphism was discovered at a locus whose expression appears to be regulated by gonadal steroids. In general, it appears that gonadal steroids exert a quantitative influence over several proteins in the MPO and in the VMH, and that the pattern of proteins affected and the direction of the effect are both area and gender specific.

ISSN:0028-3835    

DOI:10.1159/000124183

出版商:S. Karger AG    

年代:1985

数据来源: Karger