摘要:

To elucidate the effect of acute behavioral stress on plasma and cerebrospinal fluid (CSF) concentrations of adrenocorticotropic hormone (ACTH) and β-endorphin, rhesus monkeys were subjected to 30 min of confinement stress. Simultaneous plasma and. CSF samples revealed no significant change in CSF ACTH or β-endorphin up to 120 min after the onset of the stress despite significant elevations in plasma cortisol, ACTH, and β-endorphin. It is suggested that acute behavioral stress does not alter CSF ACTH or β-endorphin, and that this information may be clinically useful for future human studies of CSF ACTH and β-endorphin in neuropsychiatric illne

ISSN:0028-3835    

DOI:10.1159/000124061

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The inhibitory effect of melatonin on evoked dopamine release from the hypothalamus was studied in adult male rats throughout a 24-hour period. The animals were maintained under a daily schedule of 14 h of light (0.00–14.00 h) and 10 h of darkness. The inhibition of dopamine release in vitro by 1 µM melatonin clearly exhibited a 24-hour rhythm with a peak at 5.00 h and almost no inhibition at 15.00 h. The concentrations of melatonin needed to produce this effect were similar throughout the 24-hour cycle, although the actual amount of inhibition at any given concentration of melatonin varied. Other indole derivatives, with the exception of 5-methoxy tryptophol, did not affect significantly the release of 3H-dopamine from the male rat hypothalami. The inhibition of dopamine release by melatonin was not observed in newborn rats but developed during the first week of life, reaching a plateau level between 6 and 7 days postnatally. However, the difference between the amount of inhibition by melatonin at 5.00 h and at 8.00 h existed from the time the inhibition was first observed. The change in amplitude of this difference was due not to differences in the apparent affinity towards melatonin but to increase in the maximal inhibition observed at 5.00 h. The data indicate that the hypothalamic sensitivity to melatonin exhibits a circadian rhythm, and that this develops postnatally prior to the development of circadian variations in melatonin levels, i.e. the ‘melatonin rhythm’. In addition, the data suggest that the occurrence of the diurnal rhythm in sensitivity is not simply the consequence of a down-regulation of melatonin receptors by melatonin released from the pineal gland the previous

ISSN:0028-3835    

DOI:10.1159/000124062

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The distribution of immunoreactive corticotropin-releasing hormone (CRF) in the forebrain and pituitary of the frog Rana ridibunda was studied by means of specific radioimmunoassay and immunohistochemistry using the indirect immunofluorescence and the peroxidase-antiperoxidase techniques. Relatively high concentrations of CRF-like material were found in both chiasmatic and infundibular regions of the hypothalamus (352 ± 11 and 422 ± 36 pg, respectively). Large amounts of CRF were also found in neurointermediate lobe extracts. Standard curves of synthetic CRF and the dilution curves for hypothalamic or neurointermediate lobe extracts were parallel. After Sephadex G-75 gel filtration, CRF-like immunoreactivity eluted in a single peak, in the same position as synthetic ovine CRF. Reversed-phase high-performance liquid chromatography of the material purified on Sephadex G-75 revealed 5 components with CRF-like immunoreactivity. The major peak had a retention time of 22 min as compared to 25.4 min for ovine CRF and 36 min for rat CRF. The detection of CRF-like immunoreactivity in neurons was facilitated by colchicine pretreatment of the frogs. The great majority of the CRF-positive perikarya were seen in the ventral region of the preoptic nucleus. A few scattered perikarya were also observed in the dorsal preoptic nucleus and in the retrochiasmatic region. Immunoreactive fibers were found in the infundibular nucleus and in various extrahypothalamic zones. CRF-containing neurons were apparently distinct from mesotocinergic and vasotocinergic neurons. A large number of immunoreactive nerve fibers were observed in the median eminence in close contact with the capillaries of the pituitary portal plexus and in the neural lobe. A few CRF-positive fibers were detected in the intermediate lobe, whereas the distal lobe was totally negative. These results show that the diencephalon and pars intermedia-nervosa of the frog contain a peptide immunologically related to mammalian CR

ISSN:0028-3835    

DOI:10.1159/000124063

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Blood was collected at 20-second intervals from the external carotid artery and from the dorsal longitudinal sagittal sinus (sagittal sinus, SS) of ovariectomized sheep. The point of SS catheterization was very near the point at which diencephalic effluent entered the SS. Concentrations of beta-endorphin (β-EP) immunoreactivity were quantified by radioimmunoassay procedures in blood plasma and in cerebrospinal fluid (CSF) from the cisterna magna. Increases in plasma β-EP concentration were provoked by intracarotid injection of naloxone and by experimental production of bacteremia (i.e., intravascular bacteria), but these procedures failed to increase β-EP in CSF. Quantities of β-EP in plasma samples from the SS were assumed to represent arterial contribution (minus tissue uptake), diencephalic secretion, and retrograde delivery of pituitary β-EP to the diencephalic effluent. The arterial contribution was removed mathematically by subtracting the arterial plasma β-EP concentration from the concurrent SS plasma concentration of β-EP to yield a paired arteriovenous (AV) difference. When this AV difference was consistently positive and satisfied our statistical criterion for being greater than zero, we concluded that either pituitary β-EP was delivered in a retrograde manner to diencephalon or the diencephalon secreted β-EP. However, this situation occurred in only 5 of 31 periods examined. Furthermore, only 2 of these 5 periods occurred during times of increasing arterial concentrations of β-EP. Such concurrence would be expected if both changes were caused by a major discharge of β-EP from the pituitary gland. Therefore, the present results provide little evidence for retrograde delivery of pituitary β-EP to the brain without system

ISSN:0028-3835    

DOI:10.1159/000124132

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

In the present work we demonstrate by means of quantitative in vitro autoradiography that the vasoactive intestinal peptide (VIP) is able to increase the number of serotonini (5-HT1) binding sites in the dorsal subiculum of the rat hippocampus and to decrease them in the suprachiasmatic nucleus (SCN). Bilateral adrenalectomy (ADX) for 6 days counteracted the stimulatory effect of VIP on 5-HT1 binding sites in the dorsal subiculum, but did not modify the inhibitory effect of the peptide in the SCN. Moreover, ADX increased 5-HT1 binding sites in response to VIP in various subfields of the hippocampus as well as in the superior colliculus and in the dorsal lateral septum, but this effect was not observed in normal or in ADX rats bearing a corticosterone implant. The present data are suggestive of a possible interaction between VIP and 5-HT in the regulation of the SCN and of a modulatory role of adrenal steroids in VIP activity in the hippocampal formation.

ISSN:0028-3835    

DOI:10.1159/000124133

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

The effect of 5-hydroxytryptophan (5-HTP), a serotonin precursor, and p-chloroamphetamine (PCA), a serotonin neurotoxin, selective for serotoninergic neurons, that depletes serotonin (5-HT) levels in brain, on the luteinizing hormone (LH) release response to estrogen-progesterone (E-P) was studied in prepubertal female rats of different ages. E-P decreased LH levels on days 16, 18 and 20, increasing the levels of the pituitary hormone at day 26 of age. Destruction of the serotoninergic system advanced the onset of the positive feed-back mechanism, since the rats pretreated with PCA showed at day 20 an LH release by E-P administration while in the controls of the same age the ovarian hormones decreased the LH concentration. On the other hand, PCA potentiated the positive feed-back mechanism of E-P on LH in 26-day-old rats, while at this age the LH release response to E-P was significantly reduced by the administration of 5-HTP. These results suggest that the serotoninergic system has an inhibitory effect on the development of the positive feed-back of ovarian steroids on LH secretion, that could be representative of a regulatory participation of serotonin in the onset of puberty. 5-HTP stimulated LH release on days 16, 18 and 20, but did not modify the LH concentration of day 26. Since between 20 and 26 days of age the positive feed-back mechanism matures, the possibility arise that the modification in the effect of serotonin on LH release on day 26 is connected with the physiological changes in the gonadotropin control that occur after day 20 in the female rat.

ISSN:0028-3835    

DOI:10.1159/000124064

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Adult female rats were implanted with permanent cannulae in the third ventricle of the brain and allowed to recover regular 4-day estrous cycles. They received intrajugular cannulae on the morning of proestrus and later between 12.00–13.00 h catecholamines – norepinephrine (NE; 5.3 or 15.9 µg), dopamine (DA; 5.3 µg), epinephrine (E; 5.3 or 15.9 µg) or vehicle (artificial CSF) – were administered intraventricularly. Plasma LH levels were measured in blood samples obtained prior to and 10, 20, 30 or 60 min after catecholamine injections. While NE or DA failed to alter basal plasma LH levels, E evoked a significant 2-fold rise in plasma LH levels. Quite unexpectedly, however, infusion of E (18.5 µg) over a 30-min period during the critical period failed to either reverse the pentobarbital-blockade of ovulation or stimulate LH release. Prior suppression of E levels selectively with LY 78335 blocked the preovulatory LH surge and ovulation. However, intraventricular E failed to evoke LH release in these LY 78335-blocked proestrous rats, an observation suggestive of some α1-adrenoreceptor blocking action of the drug. In contrast, the α1-adrenoreceptor blocking action was not evident in the estrogen, progesterone-primed ovariectomized rats similarly pretreated with LY 78335. These studies show that (1) E-containing neurons in the hypothalamus may play an important role in the preovulatory LH release; (2) LY 78335 may exert inhibitory effects on preovulatory LH release, in part, by blocking α1-adrenoreceptors, and (3) participation of NE and DA, if any, in evoking preovulatory LH release remains to be

ISSN:0028-3835    

DOI:10.1159/000124065

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

In order to characterize the properties of tuberohypophysial dopaminergic neurons which terminate in the intermediate (IL) and neural (NL) lobes of the pituitary gland a technique was developed which permitted the selective dissection of the rat pituitary into its three distinct lobes (NL, IL and anterior lobe, AL). The success of the dissection was evaluated histologically and biochemically by measuring the distribution of peptide hormones characteristic of the dissected regions. As would be predicted, prolactin was found almost exclusively in the AL, arginine-vasopressin in the NL and α-melanotropin in the IL. Over two-thirds of total immunoreactive β-endorphin was located in the IL and less than 30% was found in the AL. The concentration of dopamine (DA) was greater in the IL than in the NL, but the rate of turnover of the amine was approximately the same suggesting that the basal activity of tuberohypophysial DA neurons is similar in both regions. On the other hand, the turnover of DA in the IL, but not NL, was increased following the administration of a DA antagonist (haloperidol) and decreased following a DA agonist (bromocriptine). Thus, the activity of DA neurons terminating in the IL is regulated, at least in part, by DA receptor-mediated mechanisms and in this regard these neurons resemble DA neurons terminating in the nucleus accumbens and striatum. Since DA turnover in NL was not altered by the administration of haloperidol or bromocriptine it is proposed that these neurons lack DA receptor-mediated regulatory mechanisms and thus resemble tuberoinfundibular DA neurons terminating in the median eminenc

ISSN:0028-3835    

DOI:10.1159/000124066

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

We have investigated the role of progesterone in the mating-induced release of luteinizing hormone (LH) and ovulation in female rats exposed to a 60-day period of constant light (LL). Plasma LH and progesterone concentrations were increased after mating; plasma estradiol concentrations, although not increased after mating, were increased compared with the concentrations in female rats on light-dark (LD) exposure during diestrus, proestrus evening and estrus. Progesterone induced ovulation in about half the number of female rats exposed to long-term LL, and in these animals, there was a significant increase in pituitary responsiveness to luteinizing hormone releasing hormone (LHRH) 5 h after progesterone injection. The magnitude of the priming effect of LHRH was markedly increased 2 h after progesterone treatment. Treatment with sodium pentobarbitone (SP) 15 min before an injection of progesterone, blocked the increase in pituitary responsiveness to LHRH 5 h later, but treatment with SP 4 h before progesterone injection did not block the increase in the magnitude of the priming effect of LHRH. These results suggest that progesterone acts both at the brain and pituitary to facilitate LH release, and that the increase in plasma progesterone produced by mating is at least partly responsible for the LH surge induced by mating in LL rats.

ISSN:0028-3835    

DOI:10.1159/000124067

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Pineal serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine (NE) and dopamine (DA) were measured by high-pressure liquid chromatography with electrochemical detection and serum melatonin was measured by radioimmunoassay in rats aged 3 weeks, 8 weeks and 18 months. They were killed either at mid-light or mid-dark of a 12 h light:12 h dark cycle. Diurnal rhythms were observed for 5-HT and 5-HIAA in all ages studied while those for NE and DA were not observed in the 18-month-old animals. Pineal 5-HT and 5-HIAA were higher in 3-week-old rats at mid-dark, and lower at mid-light than in older animals. The pineal content of NE was lower in the 3-week-old rats at mid-dark and mid-light compared with that in the 8-week-old while the DA content was lower at mid-dark. In addition, pineal 5-HT, 5-HIAA, NE and DA were lower in the 18-month-old than in the 8-week-old animals at mid-dark. At mid-dark serum melatonin levels showed an age-related decrease. This study shows that an age-related decrease of pineal 5-HT, 5-HIAA, NE and DA can only be demonstrated at mid-dark and that the age-related decrease of melatonin may not be due to a decrease in sympathetic activity.

ISSN:0028-3835    

DOI:10.1159/000124068

出版商:S. Karger AG    

年代:1985

数据来源: Karger