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Biomedical subjects

W Wuttke

Publications and source records attributed to W Wuttke.

At least 199 records · Page 11Linked to original sources
PubMed1980

The role of monoamines in female puberty.

The estradiol positive feedback mechanism appears to become mature between days 10 and 20 after birth. Rising serum prolactin levels between day 20 after birth and puberty are correlated with high hypothalamic norepinephrine turnover. High prolactin levels stimulate hypothalamic dopamine (DA) turnover, which may actively inhibit hypothalamic luteinizing hormone-releasing hormone (LHRH) release. Hypothalamic DNA receptor sensitivity is high in 10- to 20-day-old rats and gradually decreases between day 20 after birth and puberty. The reason for this desensitization may be the high hypothalamic DA turnover. This may result in a less strong inhibition of LHRH release allowing the positive feedback action of estradiol to elicit the first preovulatory luteinizing hormone (LH) surge initiating puberty.

Adrenalectomy↗
PubMed1980

Hyperpolarization of hypothalamic parvocellular neurons by 17 beta-estradiol and their identification through intracellular staining with procion yellow.

Intracellular recordings and injections of procion yellow (PY) were made in parvocellular neurons in hypothalamic slices of female guinea pigs. Eighty-five neurons, with an average resting membrane potential of -35 mV, were recorded in the arcuate (ARC) ventromedial (VM), and in the cell-poor zones between the ARC and VM. Eleven of the ARC neurons and four neurons from the cell-poor zone could be driven antidromically by median eminence (ME) stimulation, nine other neurons from the three areas could be driven orthodromically by stria terminalis (ST) stimulation. Twenty-eight parvocellular neurons were tested with 17 beta-estradiol (E2), which was applied in the bathing medium as the free steroid. Eleven neurons (nine ARC and two cell-poor-zone neurons) were hyperpolarized 2 to 24 mV by 10(-10) M E2 concentrations. 10(-8) M estrone concentration was without effect on three of these cells. Through the intracellular injection of PY, the estrogen-sensitive neurons (N = 11) were identified as small fusiform cells with few dendrites. Spine-like appendages were found on only one of these cells. None of the larger pyramidal-like neurons of these areas responded to the application of E2.

Animals↗
PubMed1980

Single unit recordings in the rat pineal gland: evidence for habenulo-pineal neural connections.

Extracellular potentials were recorded in the pineal gland of urethane-anesthetized rats. Two distinct populations of excitable pineal "cells" were found, the silent "cells" which were driven by habenula stimulation and the spontaneously active cells. In the former case 17 of the responses (median latency of 1.2 ms) showed a positive-negative potential, and 6 (about 1 ms latency) showed only positive potential of 1-2 ms duration. The remaining cells (114), which could not be driven by habenula stimulation, exhibited spontaneous activity with a firing frequency from less than 1 Hz to greater than 100 Hz with a median firing frequency of 10 Hz. These experiments clearly demonstrate a direct habenulo-pineal fiber pathway and furthermore show that there are neuronal elements in the pineal which are only activated by habenula stimulation.

Animals↗
PubMed1980

[Neuroendocrine regulatory mechanisms].

The main center for the control of sexual functions is located in the hypothalamus. The medical preoptic area and the mediobasal hypothalamus are sites of production of neuropeptides which are released into the hypothalamo-pituitary portal vessel system and which function as releasing and inhibiting hormones.

Animals↗
PubMed1980

Diurnal variations of plasma luteinizing hormone, follicle-stimulating hormone, and prolactin in boys and girls from birth to puberty.

Thirty-eight girls and 44 boys were evaluated for nocturnal variations in plasma LH, FSH, and PRL. The children were subdivided into 4 groups according to their stage of sexual maturation. Blood samples were collected at 1800, 2200, 0200, and 0800 h from an indwelling venous catheter. The last sampling was followed by a simultaneous LHRH/TRH test to assess pituitary hormone reserve at different ages. In neither sex were differences of plasma LH values observed in age groups 1 and 2. In age group 3 (stages 2-3), girls demonstrated increased LH levels during sleep. The response to LHRH in this group was similarily high in girls and in girls and boys in age group 4 (stages 4-5). In the oldest group, a rise of plasma LH values at night occurred in both sexes. In girls, a significant nocturnal increase of plasma FSH values was found in age group 2 (prepubertal). In age group 3 (stages 2-3), boys also developed a nocturnal rhythm, with highest plasma FSH levels during sleep. Together with these increased nocturnal plasma hormone levels, a more pronounced response to LHRH stimulation occurred. Increased plasma PRL levels were found in all children at night without increasing basal values with the onset of puberty.

Adolescent↗
PubMed1980

Influence of drugs affecting prolactin secretion on some sexually differentiated hepatic and renal enzyme activities of steroid hormone metabolism in the rat.

The effects of drugs known to modify hypophyseal release of prolactin [perphenazine, reserpine, DOPA, 2-bromo-alpha-ergocryptine-mesasilate (CB 154)] were tested on sexually differentiated enzymes of hepatic (microsomal 3 alpha- and 3 beta-hydroxysteroid dehydrogenase and 5 alpha-reductase) and renal (cytoplasmic 17 beta-hydroxysteroid dehydrogenase) steroid metabolism whose activities had previously been shown to be influenced by prolactin administration to hypophysectomized rats. None of the drugs affected the renal enzyme activity. Reserpine caused a feminization of all three hepatic activities, whereas perphenazine only affected 5 alpha-reductase. Such changes are in accordance with the hypothesis that prolactin acts as a "feminizing factor" for these activities. However, the two drugs known to decrease prolactin secretion (DOPA, CB 154) also caused some feminization. Based on changes in seminal vesicle weight, this effect of DOPA might be due to alterations in the peripheral androgen concentration.

Animals↗
PubMed1979

Involvement of catecholamines in eliciting LH peaks in 15-day-old female rats: effects of treatment with prolactin.

In the serum of 15-day-old female rats, treated either with alpha-methyl-p-tyrosine (alpha-MPT) or saline, serum LH levels were determined. From the brains of all animals the medial preoptic areas (MPO) and the anterior and posterior mediobasal hypothalami (AMBH and PMBH) were punched out and stored frozen in perchloric acid. In the punches of those animals with very high or basal LH levels catecholamine concentrations were measured radioenzymatically and on the basis of the degree of catecholamine depletion after alpha-MPT the turnover rates of dopamine (DA) and norepinephrine (NE) were calculated. NE turnover in the MPO was significantly higher in the animals with high LH levels as compared to those with low LH values. In the PMBH an inverse correlation between LH levels and NE turnover rates could be demonstrated. NE turnover in the AMBH, and DA turnover in all 3 structures did not correlate with serum LH levels. Serum FSH and prolactin levels were higher in the animals with high LH levels. These changes are similar to those observed in adult proestrous rats and it is concluded that the LH peaks in 15-day-old animals reflect a positive feedback action of estradiol. In a second experiment prolactin was administered to determine if it could prevent the occurrence of these LH peaks. Ovine prolactin (2 X 0.5 micrograms/g body weight) injected from day 8--15 suppressed serum LH levels to almost undetectable values. Catecholamine turnover measurements in these animals revealed increased DA turnover in the MPO, AMBH and PMBH, whereas NE turnover was not affected. These results indicate that DA turnover of the incertohypothalamic and of the tuberoinfundibular DA neurons is accelerated by prolactin and that an increased DA turnover in one of these systems is responsible for inhibition of LH release.

Animals↗
PubMed1979

Ontogeny of catecholamine turnover rates in limbic and hypothalamic structures in relation to serum prolactin and gonadotropin levels.

Norepinephrine (NE) and dopamine (DA) concentrations and turnover rates have been studied in the n. accumbens, medial preoptic area (MPO) and anterior and posterior parts of the mediobasal hypothalamus of developing rats. Turnover rates are determined by injection of alpha-methyl-p-tyrosine 30 and 90 min prior to decapitation. NE concentrations and turnover in the n. accumbens were low in all age groups with slightly increased values between days 20 and 35 after birth whereas DA concentrations and turnover rates were low at day 15 and 20 and at high adult values by day 25 after birth. Medial preoptic and anterior mediobasal hypothalamic catecholamines exhibited a rather unique pattern. Concentrations and turnover rates were low in 15-day-old animals and increased between days 20 and 30 to very high values. Such high values were never observed in adult diestrous animals. The same pattern was also observed in the posterior mediobasal hypothalamus for NE concentrations and turnover rates whereas the respective values for DA showed relatively large fluctuations. On the basis of catecholamine measurements 30 and 90 min after blockade of tyrosine hydroxylase an attempt was also made to differentiate turnover rates of the functional and of the storage pool. Serum LH levels in the 15-day-old animals showed large fluctuations. FSH levels were high and prolactin levels were low. At the time of increased preoptic and hypothalamic NE and DA turnover rates, serum prolactin levels were also high whereas serum LH levels were lowest between days 20 and 30 and then slightly increased. Serum FSH levels were uniformly low. The possibility is discussed that high NE turnover may stimulate pituitary LH and prolactin release by hypothalamic mechanisms. Hihgh serum prolactin levels may stimulate DA turnover which is inhibitory to pituitary LH release, thus counteracting the stimulatory effect of NE on LH-RH release. The dopaminergic inhibition of LH may be relieved at the time of puberty partially because the DA receptors become desensitized to the action of DA.

Age Factors↗
PubMed1979

Effects of chemical lesion of the ventral noradrenergic bundle or the medial preoptic area on preovulatory LH release in rats.

The noradrenergic innervation of the medial preoptic area (MPO) and the hypothalamus is provided by mesencephalic neurons via the ventral noradrenergic tract. Fibers of these neurons emerge through the MPO. Bilateral microinjections of 6-OHDA into the ventral noradrenergic bundle (VNB) depletes large parts of the diencephalon of norepinephrine (NE) and dopamine (DA). Since the total hypothalamic DA content is of intrahypothalamic origin, 6-OHDA injection into the VNB does not reduce hypothalamic DA content. Similarly microinjections of 6-OHDA into the MPO reduces hypothalamic and preoptic NE content without altering NE concentrations in other diencephalic structures. Microinjections of 6-OHDA and of the carrier solution of 6-OHDA into the VNB or into the MPO of female rats with regular estrous cycles results in a slight disturbance of the cyclic activity for few days. Within 1--4 days normal cyclic activity is resumed. Preovulatory LH release is substantially reduced 8--12 days after injection of 6-OHDA into the VNB or into the MPO. On the basis of these and previous results it is concluded that the availability of NE in the MPO is an important factor in determining the hight of the preovulatory LH surge.

Animals↗
PubMed1979

Morphological features of physiologically identified hypothalamic neurons as revealed by intracellular marking.

In the in vitro slice preparation intracellular recordings and injections of procion yellow (PY) were made in neurons of the hypothalamus. Of these neurons, one medial preoptic-anterior hypothalamus (MPO-AH) and four arcuate-ventromedial hypothalamus (ARC-VM) neurons were driven by electrical stimulation of the median eminence area (ME). Two other MPO-AH and five other ARC-VM neurons were driven by stimulation of the stria terminalis (ST). On the basis of the PY injections two morphologically distinct cell types were delineated: a larger multipolar cell type with a polygonal perikaryon was found with equal frequency in the MPO-AH and the ARC-VM. A smaller fusiform cell type was encountered mainly in the ARC-VM. On the secondary dendrites of both cell types spine-like appendages were seldom seen, but dendritic swellings were common. Some of the dendrites projected to capillaries in both areas and presumably contacted them. The axons were usually tortuous and could only be traced a short distance.

Animals↗
PubMed1979

Annual rhythms of luteinizing hormone, follicle-stimulating hormone, prolactin and testosterone in the serum of male rhesus monkeys.

Six male rhesus monkeys were kept under rigidly controlled conditions for 1-2 years. During August of the first year a thyrotrophin releasing hormone (TRH) test was performed on each of the monkeys by giving 10 microgram TRH as a bolus injection. Significantly increased serum prolactin levels occurred 15 min after the injection. After a training period of 2 months, during which blood samples were collected every other day by puncture of the saphenous vein, blood was collected three times a week for 14 months. Serum levels of prolactin, LH, FSH and testosterone were measured by radioimmunoassay. Mean serum prolactin levels increased significantly during June, July and August in all six animals. Peak levels were observed in August and September and then levels declined gradually to reach a minimum in April and May. Mean serum testosterone levels closely paralleled the annual pattern of prolactin. Mean serum LH levels significantly decreased during the time when mean serum prolactin and testosterone levels were increasing and they increased again at the time of decreasing mean prolactin levels, i.e. mean serum LH and prolactin were negatively correlated. In individual monkeys, however, a rigid negative correlation between serum prolactin and LH could not be demonstrated. Mean serum FSH levels did not change significantly.

Animals↗