Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Preoptic Area”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1976

Efferents from medial basal forebrain and hypothalamus in the rat. I. An autoradiographic study of the medial preoptic area.

Efferent projections from the medial and periventricular preoptic area, bed nucleus of the stria terminalis and nuclei of the diagonal band were traced using tritiated amino acid autoradiography in albino rats. Medial and periventricular preoptic area efferents were not restricted to short-axon projections. Ascending projections from the medial preoptic area (mPOA) were traced through the diagonal band into the septum. Descending mPOA axons coursed in the medial parts of the medial forebrain bundle. Projections to most hypothalamic nuclei, including the arcuate nucleus and median eminence, were observed. In the midbrain, mPOA efferents were distributed in the central grey, raphe nuclei, ventral tegmental area and reticular formation. Projections from the mPOA were also observed to the amygdala through the stria terminalis, to the lateral habenula through the stria medullaris, and to the periventricular thalamus. Axons of the most medial and periventricular preoptic area (pvPOA) neurons had a distribution similar to more lateral mPOA neurons but their longest-axoned projections were weaker. The pvPOA did not send axons through the stria medullaris but did project more heavily than the more lateral mPOA to the arcuate nucleus and median eminence. Projections from the bed nucleus of the stria terminalis (nST) were in most respects similar to those from the medial preoptic area, with the major addition of a projection to the accessory olfactory bulb. The nuclei of the diagonal band of Broca (nDBB) gave a different pattern of projections than mPOA or nST, projecting, for instance, to the medial septum and hippocampus. Descending nDBB efferents ran in the ventral portion of the medial forebrain bundle. Among hypothalamic cell groups, only the medial mammillary nuclei received nDBB projections. nDBB efferents also distributed in the medial and lateral habenular nuclei and the mediodorsal thalamic nucleus.

Animals↗
PubMed1979

Enhancement of immunoreactive somatostatin release into hypophysial portal blood by electrical stimulation of the preoptic area in the rat.

Electrical stimulation of the preoptic area resulted in a significant increase in the secretion rate of immunoreactive somatostatin (IRS) and its concentration in the hypophysial portal blood of urethane-anesthetized rats. In contrast, stimulation of the ventromedial nucleus did not cause any changes in portal immunoreactive somatostatin. The flow rate of portal blood also increased significantly by electrical stimuli to the preoptic area but not to the ventromedial hypothalamus. These findings support the view that the preoptic area plays an inhibitory role in the regulation of GH secretion by increasing the release of somatostatin into hypophysial portal vessels in the rat.

Animals↗
PubMed1978

Activation of hypothalamic neuronal activity by the electrolytic deposition of iron into the preoptic area.

Changes in brain activity after electrochemical stimulation of the preoptic area of pro-oestrous rats were studied by the measurement of the electro-encephalogram (EEG) of the frontal cortex and the recording of single neurones in the anterior hypothalamus. All rats were anaesthetized with urethane between 10.00 and 12.00 h to allow prolonged electrophysiological recording and to block the spontaneous surge of LH during the afternoon. Electrochemical stimulation was applied, between 12.00 and 14.00 h, as an anodal current through an implanted steel electrode; this caused the electrolytic deposition of iron and evoked the release of LH and ovulation. Electrochemical stimulation of the preoptic area changed the cortical EEG, either immediately or after a delay of a few minutes, from a labile pattern with alternate periods of arousal and slow-wave sleep, to a stage of continuous arousal which persisted for the remainder of the recording period (2--3 h). Conversely, the EEG pattern of the cortex was not disturbed by electrolytic lesions placed in the preoptic area through a platinum electrode. Electrochemical stimulation of the arcuate region of the hypothalamus, the lateral septal area, the medial amygdaloid complex and the anterior parts of the thalamus caused no obvious change in the EEG patterns. Ipsilateral anterior hypothalamic neurones, about 1 mm caudal to the focus of electrochemical stimulation, displayed an immediate decrease in electrical activity after application of the current. After 10--20 min however, the rates of discharge of action potentials in 9 out of the 16 neurones under consideration increased progressively from 0.5 to 15--25 action potentials/s and these rates were maintained until the recordings were lost after 90--230 min. No such acceleration in electrical activity was observed in neurones on the contralateral side. Iron deposited during electrochemical stimulation was precipitated as sulphide and stained by Timm's method. There was a central damaged area of radius 0.6 mm surrounded by an 'undamaged' area with considerable infiltration of iron, up to a distance of 1.7 mm from the electrode tip. Cells within the area of infiltration did not stain for iron 10 min after electrochemical stimulation, but after 30 min, neural elements in this peripheral zone were stained in a manner similar to the Golgi method. The concentrations of LH in the plasma remained unchanged in all rats for 10--15 min after electrochemical stimulation. Thereafter, the concentrations increased progressively and approximately in parallel to the changes in action potential activity until, after 2 h, the individual concentrations of 300--600 ng LH/ml were more than six times the values obtained before stimulation. Bilateral electrochemical stimulation resulted in appreciably higher concentrations of LH and produced values close to those observed during the pro-oestrous surge of the hormone...

Action Potentials↗
PubMed1976

Direct neural connection from the medial preoptic area to the hypothalamic arcuate nucleus of the rat.

Direct neural connections from the medial preoptic area (MPOA) to the arcuate nucleus were studied on light and electron microscope level by a multistep experimental procedure. The hypothalamic deafferentation technique of Halász and Pupp (1965) was used in itself or was combined with electrolytic lesions. In order to eliminate all fibers of more rostral source traversing the medial preoptic area an extended rostral preoptic deafferentation was made, and a survival time of at least 3 weeks was chosen to allow for the complete disappearance of the degenerated fragments from the arcuate nucleus. In the main experimental group the medial preoptic area was destroyed by an electrolytic lesion 3 or more weeks following such rostral preoptic deafferentations. In these animals degenerated fibers and terminals certainly of preoptic origin were found distributed bilaterally, with a predominance on the side of the lesion. - These data suggest that axons originating from medial preoptic neurons terminate in the arcuate nucleus, thus constituting a preoptico-tuberal pathway.

Animals↗
PubMed1976

Studies on the role of the preoptic area in the control of reproductive function in the rat.

The present study was designed to determine the effects of bilateral lesions restricted to the medial preoptic area on reproductive function in rats. Adult female rats were placed in a stereotaxic instrument, and bilateral lesions were made in the medial preoptic area of the diencephalon using an anodic current and platinum or stainless steel electrodes. Both types of lesions produced identical effects. Most animals with lesions restricted to the medial preoptic area showed repeated periods of pseudopregnancy for the duration of their lives. Ova were detected in the oviducts on the day of estrus between pseudopregnancies, and deciduomata could be produced by uterine traumatization during pseudopregnancy. Daily administration of lergotrile mesylate, a dopamine agonist, for about two weeks, to the pseudopregnant rats with lesions resulted in the appearance of normal 4 or 5-day estrous cycles. These results suggest that the medial preoptic area may not be necessary for ovulation in the rat, and that the normal function of the preoptic area in the control of reproductive cyclicity may be mediated via dopaminergic neurons. In agreement with earlier studies, we found that lesions that extended into the anterior hypothalamus resulted in constant estrus.

Acetonitriles↗
PubMed1976

Characterization of the androgen receptors in the hypothalamus, preoptic area and brain cortex of the rat.

The specific androgen receptors for testosterone (T) (1) and 5alpha-dihydrotestosterone (DHT) in the cytosol fraction of the hypothalamus, preoptic area and brain cortex of the rat have been characterized using electrophoresis and isoelectric focusing in polyacrylamide gels. After labeling of the cytosol fractions in vivo and in vitro we were able to demonstrate androgen-receptor complexes moving with an electrophoretic mobility (R(f) of 0.5 in 3.25% acrylamide gels containing 0.5% agarose and 10% glycerol. Polyacrylamide gel electrophoresis was used as a quantitative assay for androgen receptors in the tissues. The hypothalamus, preoptic area and brain cortex were found to possess a single class of high affinity binding sites for androgens and the dissociation constants (K(D) were estimated to be 3.4, 4.3 and 2.6 X 10 (-10M) respectively. The binding capacities were 3.7 (hypothalamus), 3.5 (preoptic area) and 1.8 X 10 (-15) (brain cortex) moles of high affinity binding sites per mg protein. Like other androgen-receptor complexes, the testosterone-receptor complexes of the hypothalamus, preoptic area and brain cortex were temperature labile, sulfhydryl dependent and revealed a very slow rate of dissociation at o degrees C (t1/2 greater than 36 hr). The receptors in all the tissues had an isoelectric point of 5.8. The steroid specificity of the cytoplasmic androgen receptors was tested in vitro by the competing efficiency of different unlabeled steroids for (3H)-testosterone binding. In the three tissues in investigation the following order of affinity was found: DHT greater than T greater than Cyproterone acetate greater than progesterone greater than androstenedione greater than 17beta-estradiol. Cortisol did not effect androgen binding significantly. Thus, the physiochemical characteristics of the cytoplasmic androgen receptors of the hypothalamus, preoptic area and brain cortex are very similar, if not identical, to those of the androgen receptors described in the anterior pituitary, ventral prostate, epididymis and testis.

Androgens↗
PubMed1977

Do aging changes in the preoptic area contribute to loss of cyclic endocrine function?

Two-year-old Wistar rats showing repeated periods of pseudopregnancy were compared with young rats that had electrolytic lesions placed in the medial preoptic area. Electrolytic lesions in the medial preoptic area in young rats induced repeated pseudopregnancies what were similar to those seen in the old pseudopregnant rats. Serum prolactin levels were elevated in both groups of rats. Administration of lergotrile mesylate (an ergot-dervied dopamine agonist and prolactin inhibitor) resulted in a reduction in serum prolactin levels and in the appearance of normal consecutive 4- or 5-day estrous cycles in the old rats and in the young rats with brain lesions. These results suggest that the repeated periods of pseudopregnancy in the aged rats may result from a deficiency in dopamine or from an abnormality in dopamine metabolism in neurons arising or passing through the medial preoptic area.

Aging↗
PubMed1977

Direct projection from the medial preoptic area to the median eminence of the cat.

The projection from the medial preoptic area to the median eminence of the cat was clarified by electron microscopy. After placing the electrolytic lesion in the preoptic area several kinds of degenerating neuronal processes and terminals were observed in the external layer of the median eminence. The one was dark shrunk terminals containing dense cored vesicles, the other was the dark ones containing myeline figure-like structure. The relationship between catecholamine-containing nerve endings and RH/IH-containing endings in the external layer of the median eminence was discussed.

Animals↗
PubMed1977

A daily neural signal for luteinizing hormone release in the untreated ovariectomized rat: changes in gonadotropin-releasing hormone content of the preoptic area and hypothalamus throughout the day.

Gonadotropin-releasing hormone (GnRH) content of preoptic areas (POA) and hypothalami, and serum gonadotropins of rats ovariectomized six weeks earlier were measured throughout the day in two experiments. In the first, rats were decapitated at 2 h intervals between 0800 and 1800 h. The entire preoptic-hypothalamic region was removed and extracted for radioimmunoassay (RIA) of GnRH. Serum gonadotropins measured by RIA were highly variable but mean concentrations were not significantly different throughout the day. However, preoptic hypothalamic content of GnRH declined markedly between 1000 and 1200 h. In the second experiment, 75 rats were divided into three groups and were untreated or were implanted sc with empty Silastic capsules or capsules containing estradiol-17beta (E2). Two days later, groups of five rats from each of the three treatment groups were decapitated at 0800, 1100, 1400, 1700 and 2000 h. The preoptic area was separated from the hypothalamus by a transverse cut at the caudal aspect of the optic chiasm. POA and hypothalamic content of GnRH correlated well (r=0.74, P less than 0.001, n=75). Two-way analysis of variance failed to reveal any effect of treatment on the GnRH content in either the POA or hypothalamus. GnRH content of both regions decreased significantly between 1100 and 1700h regardless of whether E2 was administered. In striking contrast, gonadotropin surges occurred in the late afternoon only in the E2-treated rats. Serum GnRH was undetectable (less than 5 pg/ml) in all groups of animals. These experiments demonstrate that in the untreated ovariectomized rat GnRH content of the POA and hypothalamus decreases during the early afternoon. This study supports the concent of a daily neural signal for LH release and that E2 is necessary for expression of the daily LH surge in the ovariectomized rat.

Animals↗
PubMed1976

Immunoreactive luteinizing hormone releasing factor in pituitary stalk blood from female rats: sex steroid modulation of response to electrical stimulation of preoptic area or median eminence.

The effects of sex steroid hormones on the responsiveness of the neural mechanism responsible for the secretion of LH-RF have been examined in the female rat. Responsiveness was determined at pro-oestrus by measuring the increments in immunoreactive LH-RF of pituitary stalk blood produced by electrical stimulation of the medial preoptic area or median eminence. Ovariectomy on the morning of dioestrus reduced the LH-RF response to preoptic stimulation while oestradiol benzoate (OB) or testosterone propionate (TP) administered immediately after ovariectomy significantly augmented the response. The facilitatory effect of TP was possibly due to its conversion to an aromatized derivative since 5alpha-dihydrotestosterone monobenzoate was ineffective. Progesterone did not facilitate preoptic responsiveness, and, when administered to animals ovariectomized at 12.00 h of pro-oestrus, reduced the LH-RF response at 18.00 h the same day. Stimulation of the median eminence produced a significantly greater increment in LH-RF than stimulation of the preoptic area. The facilitatory action of OB on the LH-RF response was less marked for median eminence compared with preoptic stimulation. The administration of ICI 46474 at 17.00 h of dioestrus did not reduce preoptic responsiveness on the morning of the next day, suggesting that this compound does not act as an 'antioestrogen' at the level of the preoptic area.

Animals↗
PubMed1977

Sex differences in dentritic patterns in hamster preoptic area.

Sexual dimorphism is described in the dentritic field pattern of Golgi-stained neurons from the dorsomedial preoptic area of adult golden hamsters (Mesocricetus auratus). Data were obtained through a mathematical reconstruction of dentritic densities of neurons sampled from this area in males and females. Males tended to have a central concentration, while females showed an irregular dendritic density distribution with concentrations dorsolateral, ventral and medial to the area of highest dentriic density in the males. These results suggest sex differences in the afferent inputs to neurons in the dorsomedial preoptic area which may be related to functional sexual dimorphism in physiology and behavior.

Animals↗
PubMed1978

Autoradiographic evidence for pathways from the medial preoptic area to the midbrain involved in the drinking response to angiotensin II.

The 3H-amino acid autoradiographic method was used to localize intracerebral sites from which angiotensin II (AII) elicits drinking and to identify their efferent neural pathways. Small injections (0.02-0.1 mul) of AII and 3H-amino acid mixtures were injected together or separately into widespread regions of the forebrain of adult rats in normal food and water balance. From an analysis of 39 positive and negative injection sites it was concluded that the caudal half of the medial preoptic area and the adjacent rostral part of the anterior hypothalamic area are sensitive to AII. Two anatomically defined pathways arising from neurons within this region were identified. One descends through the medial forebrain bundle and appears to terminate in the lateral hypothalamic area, the ventromedial nucleus, the mammillary body, and the ventral tegmental area. The other descends through the periventricular region and posterior hypothalamic area to end in the midbrain central gray. Additional widespread connections with the amygdala, septum, habenula, and pons appear to arise in the lateral preoptic area (Swanson, '76). Combined AII-3H-amino acid injections centered in the subfornical organ only elicited drinking in those cases in which injected label diffuse through the third ventricle to the medial preoptic area. No efferent pathways were identified in experiments in which a small injection (0.02 mul) heavily labeled cells strictly confined to the subfornical organ and there was no ventricular spread of label.

Angiotensin II↗
PubMed1979

Effects of lesions of the amygdala, preoptic area, and hypothalamus on estradiol-induced activity in the female rat.

Lesions of the anterior hypothalamic nucleus and the medial preoptic area sharply attenuated enhancement of wheel running by estradiol benzoate in ovariectomized female rats. Lesions of the corticomedial amygdala had no effect on this behavior. The hormonal effects on activity were largely independent of any changes in body weight. Results of this first experiment indicated that the anterior hypothalamic and medial preoptic areas are critically involved in the induction of activity by estradiol. However, this experiment provided no support for suggestions that the corticomedial amygdala inhibits those structures that mediate the estrogenic induction of activity. In the second experiment, food deprivation was used to stimulate activity. Results of this experiment suggested that the reduction in the ability of estradiol to induce activity following anterior hypothalamic and medial preoptic lesions does not reflect a general inability to become more active.

Amygdala↗
PubMed1976

Immunoreactive luteinizing hormone releasing factor in rat pituitary stalk blood: effects of electrical stimulation of the medial preoptic area.

Blood was collected from the cut pituitary stalk of male and female rats before and during the application of an electrical stimulus to the medial preoptic area. The plasma was assayed for immunoreactive LH releasing factor (RF) by a double antibody radioimmunoassay using a specific antiserum raised in rabbits against the free acid derivative of the decapeptide LH-RF conjugated to bovine serum albumin. The decapeptide (used as a standard) and pituitary stalk plasma cross-reacted in a similar manner with the antiserum. Stimulation of the preoptic area increased significantly the amount of LH-RF in pituitary stalk plasma in both male and female rats. The increase in LH-RF was linearly related to the strength of the stimulating current, and the amount of LH-RF liberated diminished on cessation of the stimulus. The concentration of LH-RF in pituitary stalk plasma from female rats was significantly greater than that in jugular venous plasma. The magnitudes of the mean increments of LH-RF in pituitary stalk plasma (stimulation minus pre-stimulation values) at various times of the oestrous cycle in female rats suggest that between 18.00 h of dioestrus and 13.00 h of pro-oestrus there is an increase in sensitivity of the LH-RF secretory mechanism to electrical stimulation. However, the increments decreased in magnitude between 13.00 and 18.00 h of pro-oestrus, indicating that the marked increase in responsiveness of the hypothalamo-hypophysial system to electrical stimulation which occurs during this period is due mainly to a change in sensitivity of the pituitary gonadotrophs to LH-RF. The LH-RF in pituitary stalk plasma collected before application of the stimulus was higher at some of the times examined during pro-oestrus than at other times of the oestrous cycle. A higher level of the secretion of the factor may be important for the full development of the priming effect of LH-RF and, consequently, the marked increase in responsiveness of the pituitary gland which occurs during the afternoon of pro-oestrus.

Animals↗
PubMed1979

Induced ovulation in aged female rats by L-dopa implants into the medial preoptic area.

Direct placement of L-dopa into the medial preoptic area (MPOA) of aged pseudopregnant or constant vaginal estrous female rats resulted in a reinitiation of vaginal cycles and ovulation. Similar treatment with L-dopa in the dorsomedial septum or cortex was ineffective. Direct placement of leucine into any of the three brain regions did not have an effect on ovarian function. Intermittent treatment with L-dopa to MPOA was found to reinstate and maintain vaginal cycles in constant estrous females only when administered on the day of vaginal estrus of successive cycles. These findings support the hypothesis that age-dependent disturbances in ovarian function may be initiated by changes in neurotransmitter metabolism within the central nervous system.

Age Factors↗
PubMed1977

Thermoregulatory behaviour after repetitive cooling of the preoptic area and of the spinal cord in the rat.

The thermoregulatory behaviour of 6 rats was studied during exposure to cold and warm ambient temperatures after either the preoptic area or the cervical spinal cord had been intermittently cooled for an average of 130 h. The precooled animals worked more for heat in cold environments and for cool air in a warm environment than the control animals. This behaviour, probably due to a decreased ability of the precooled animals to retain heat, suggested that the precooled animals were not fully adapted to cold. 1974) will learn to press a lever to modify their thermal environment, and this paper describes the thermoregulatory behaviour of rats after prolonged cooling of the preoptic area, and of the spinal cord. The thermoregulatory behaviour of cold exposed and cold adapted animals has already been studied in several species (Carlton and Marks, 1958; Laties and Weiss, 1960; Revusky, 1966; balwin and Ingram, 1967).

Adaptation, Physiological↗
PubMed1979

Neural connexions between the medial forebrain bundle, the preoptic area and the basal hypothalamus in the rat: an electrophysiological study.

1. Electrophysiological experiments have been performed on intact cycling female rats to investigate the neural connexions that exist between the medial forebrain bundle, the anterior hypothalamic region, which included the preoptic area, and the basal hypothalamus. Recordings have been made from a total of 351 neurones in the anterior hypothalamus of which 216 were responsive to stimulation of either or both the medial forebrain bundle and basal hypothalamus (arcuate and ventromedial nuclei).2. Forty-six of these cells were responsive to a stimulus applied both to the medial forebrain bundle and the basal hypothalamus with a variety of response combinations. The majority of neurones were orthodromically activated by stimulation in both sites. Inhibition by stimulation of the medial forebrain bundle coupled with orthodromic excitation from the basal hypothalamus, or the reverse situation, was also encountered frequently.3. A few cells were antidromically invaded by the stimulation of the medial forebrain bundle and these received orthodromic or inhibitory inputs from the basal hypothalamus, although one unit outside the anterior hypothalamus was antidromically activated by both stimuli.4. Ninety per cent of all the doubly responsive units that could be antidromically activated by stimulation of the basal hypothalamus received an orthodromic input from the medial forebrain bundle, and no cells in the anterior hypothalamus that projected to the basal hypothalamus were found to receive an inhibitory input from the medial forebrain bundle.5. These results provide electrophysiological evidence for inhibitory and excitatory inputs from the medial forebrain bundle to the preoptic and anterior hypothalamic cells that either project to, or receive connexions from, the basal hypothalamus. Neurones in the preoptic area which project to the basal hypothalamus are implicated in the control of anterior pituitary function, particularly gonadotrophin secretion. These experiments, coupled with functional studies, suggest that there is an excitatory input from the medial forebrain bundle to these preoptic and anterior hypothalamic cells which may modulate adenohypophyseal secretions.

Animals↗
PubMed1979

Effects of transecting lateral neural connections of the medial preoptic area on maternal behavior in the rat: nest building, pup retrieval and prolactin secretion.

In lactating female rats bilateral parasagittal cuts transecting the dorsolateral neural connections of the medial preoptic area (MPOA) abolished nest building and retrieving components of maternal behavior, while crouching and nursing were unaffected. While few animals with these cuts were suckled when presented with pups the prolactin secretion response was undiminished when suckling did occur. Whereas previous studies have demonstrated that extensive surgical separation of the medial preoptic area-anterior hypothalamic continuum from the lateral preoptic area-lateral hypothalamus disrupts all aspects of maternal behavior, the present study has determined more specifically the zone of fibers essential for the active components of maternal behavior, i.e., nest building and retrieving. These fibers appear to enter/leave MPO dorsolaterally beneath the crossing of the anterior commissure in the region of the bed nucleus of the stria terminalis. These neural connections are not the same as those that regulate prolactin secretion in the lactating rat.

Animals↗