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 163 records · Page 9Linked to original sources
PubMed2000

Electrophysiology and pharmacology of projections from the suprachiasmatic nucleus to the ventromedial preoptic area in rat.

Extracellular and whole-cell patch-clamp recordings were made from neurons in the ventromedial preoptic area in rat horizontal brain slices. Responses to single-pulse electrical stimulation of the ipsilateral suprachiasmatic nucleus were characterized using peristimulus time histograms or postsynaptic current recordings, and bath application of neurotransmitter receptor antagonists. Extracellular recordings showed that suprachiasmatic nucleus stimulation (50-150 microA) elicited a short-latency suppression in 35 of 64 neurons (55%), with the majority (29/35, 83%) showing a biphasic response consisting of a short-latency suppression followed by a long-duration activation. In addition, 14 cells (22%) showed activation only, while 15 (23%) were unresponsive. The GABA(A) receptor antagonist bicuculline (5-10 microM) reversibly blocked suppressions evoked by suprachiasmatic nucleus stimulation (20/20 cells). In the majority of these neurons (13/20), bicuculline also unmasked an activation in response to stimulation. Activations elicited by suprachiasmatic nucleus stimulation, either in the presence or absence of bicuculline, were blocked by the non-N-methyl-D-aspartate and N-methyl-D-aspartate glutamate receptor antagonists 6,7-dinitroquinoxaline-2,3-dione and (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (10/10 cells). 6,7-Dinitroquinoxaline-2,3-dione (10 microM) selectively and reversibly blocked the initial, short-duration (<50 ms) activation, but had no effect on the longer-duration activation. In contrast, (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (10 microM) appeared to inhibit the long-duration activation selectively without affecting the initial rapid activation. Combined applications of the two ionotropic glutamate receptor antagonists blocked stimulation-induced activations completely. All the pharmacological effects were concentration dependent. Whole-cell patch-clamp recordings showed that suprachiasmatic nucleus stimulation elicited inhibitory postsynaptic currents or a combination of inhibitory and excitatory postsynaptic currents in 25 of 33 neurons tested. The inhibitory postsynaptic currents had short onset latencies (4.9+/-0.3 ms) and a reversal potential of -56.0+/-3.8 mV (n=5), and were reversibly blocked by bicuculline (5-10 microM, 4/4 cells). In the presence of bicuculline (5-10 microM), excitatory postsynaptic currents had short onset latencies (4.7+/-0.5 ms), and had a fast and a slow component. (+/-) 3-(2-Carboxypiperazin-4-yl)-propyl-1-phosphonic acid blocked the slow, but not the fast, component, whereas 6,7-dinitroquinoxaline-2, 3-dione blocked the fast, but not the slow, component (n=7). These results suggest that the projection from the suprachiasmatic nucleus conveys both inhibitory (GABA) and excitatory (glutamate) inputs to the ventromedial preoptic area. GABA(A) receptor and both non-N-methyl-D-aspartate and N-methyl-D-aspartate glutamate receptors mediate these influences. These inputs may be responsible for conveying information related to circadian phase from the suprachiasmatic nucleus to regions of the preoptic area known to be involved in regulation of sleep/waking and other physiological functions.

Animals↗
PubMed1987

Electron microscopic cytochemistry of catecholaminergic innervation of LHRH neurons in the medial preoptic area of the rat.

The synaptic interactions between catecholaminergic terminals and luteinizing hormone releasing hormone (LHRH)-containing neurons in the medial preoptic area of the rat was studied by electron microscopy using LHRH immunocytochemistry combined with 5-hydroxydopamine labeling or autoradiography after injection of 3H-dopamine or 3H-noradrenaline in the same tissue section. Axon terminals labeled with 5-hydroxydopamine, 3H-dopamine or 3H-noradrenaline were found to make synapse-like contacts with LHRH-immunoreactive nerve cell bodies and fibers in the medial preoptic area and also 5-hydroxydopamine-labeled terminals made synaptic contacts with the same LHRH-immunoreactive nerve fibers with unlabeled terminals. These findings suggest that catecholaminergic neurons may innervate LHRH-containing neurons to regulate LHRH secretion via synapses with other unknown neurons in the medial preoptic area of the rat.

Animals↗
PubMed1993

Luteinizing hormone-releasing hormone and gamma-aminobutyric acid neurons in the medial preoptic area are synaptic targets of dopamine axons originating in anterior periventricular areas.

The aim of this study was to characterize further the transmitter content and the location of the parent cells of tyrosine hydroxylase-immunoreactive boutons terminating on luteinizing hormone-releasing hormone- and glutamic acid decarboxylase-immunoreactive neurons in the rat medial preoptic area. Electron microscopic immunostaining for luteinizing hormone-releasing hormone, tyrosine hydroxylase or glutamic acid decarboxylase was performed on desipramine-pretreated (to protect norepinephrine and epinephrine axons) rats which received a stereotaxic injection of 6-hydroxydopamine into the medial preoptic area anteroventral periventricular nucleus 48 h prior to sacrifice. This treatment induced acute degeneration of dopamine axon terminals characterized by the development of autophagous cytolysosomes, an early morphological sign of catecholamine axon degeneration. To further define the cells of origin of these dopamine boutons, the anterograde marker Phaseolus vulgaris leucoagglutinin was iontophoretically applied to the zona incerta. Six days later, rats received a 6-hydroxydopamine injection into the zona incerta or the lateral ventricle, and 48 h later, double immunostaining was performed for Phaseolus vulgaris leucoagglutinin and tyrosine hydroxylase, luteinizing hormone-releasing hormone, or glutamic acid decarboxylase on preoptic area vibratome sections. Following the 6-hydroxydopamine injection into the anteroventral periventricular nucleus, autophagous cytolysosome-containing degenerated axons were found in synaptic contact with both luteinizing hormone-releasing hormone and GABA neurons in the medial preoptic area, confirming that these are dopaminergic connections. Following the double injection treatment, 6-hydroxydopamine-induced degenerated, Phaseolus vulgaris leucoagglutinin-labeled dopamine axons originating in the zona incerta were not found to contact luteinizing hormone-releasing hormone-containing or GABA cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Changes in dendritic spine density in the preoptic area of the female rat at puberty.

Preoptic area (POA) neurons stained by a modification of the Golgi-Kopsch method were studied in developing female rats. Particular attention was focused on dendritic spine densities as they might be altered in relation to the onset of puberty. Neurons in the anterior superior and posterior superior portions of the POA showed an increase in mean spine density at the age of vaginal opening. The increase in dendritic spine density in the posterior inferior quadrant of POA occurred prior to vaginal opening. The entire posterior POA maintained peak levels of spine numbers through 55 days of age, but then exhibited a dramatic drop at 75 days. Thus, modification of the neuropil may well continue at least to this age. The increases in spine densities at vaginal opening for the superior POA quadrants, followed by relatively stable values, appear to implicate these areas in the timing of the onset of puberty.

Animals↗
PubMed1980

Evidence for the existence of a sexually dimorphic nucleus in the preoptic area of the rat.

The volume of an intensely staining component of the preoptic area of the male rat is markedly larger than that of the female. Moreover, its volume in both sexes is altered by perinatal hormone exposure consistent with the view that this brain region undergoes hormone dependent sexual differentiation. The present study was carried out to determine if this sexually dimorphic area of the brain has a greater cell density than that of the surround, and if a unique population or distribution of cells, either within one sex or between males and females, characterized this region. A single coronal paraffin section (10 micrometer) through the approximate center of this sexually dimorphic area in four adult gonadectomized rats of each sex was evaluated systematically. Each cell was labelled as being inside or outside of the sexually dimorphic area. In addition to cell density per unit area the following parameters were evaluated through a closed-circuit video system: cell size, staining intensity, shape, and the presence of processes and of a nucleolus. The presence of a nucleolus was further used to identify neurons within the total population of almost 5000 cells that was evaluated. In both sexes, the sexually dimorphic area was characterized by a significantly increased cell density per unit area compared to that of the surround. On this basis, the term, the Sexually Dimorphic Nucleus of the Preoptic Area (SDN-POA) is proposed, for this region. Moreover, the SDN-POA of the male was characterized by increased neuronal density per unit area. The SDN-POA in the male was also found to contain larger cells and neurons, as determined by direct measurement of their greatest diameter, as well as a greater percentage of cells and neurons rated large on a three-point scale (small, medium, and large). No consistent differences in frequency distribution by stain intensity, shape, or the presence of cell processes were found to characterize the SDN-POA or contribute to the sexual dimorphism. It is concluded that the marked sex difference in the volume of the SDN-POA is due principally to an increase in the male of the total area of higher cell and neuronal density. However, the present results do not eliminate the possibility that more subtle differences in neuronal characteristics may exist in the SDN-POA.

Animals↗
PubMed1996

Lordosis-inhibiting effect of progesterone in female rats with lesions in septum, preoptic area, or dorsal raphe nucleus.

Radiofrequency lesions in the septum (SL), the preoptic area (POAL), or the dorsal raphe nucleus (DRL) were made in ovariectomized rats. In a control group of 16 females, ovariectomy, but no brain surgery, was performed. All animals except half of the control rats received injections of 5 mg progesterone (P) 1 h prior to the injection of 5 micrograms/kg b.w. of estradiol benzoate (EB). Instead of 5 mg P, oil was administered to half of the controls. Forty-four hours after EB, all females received 0.5 mg P. A sexual behavior test was performed 4 h after the last injection of P. The result was that oil-treated control rats showed high lordosis quotient (LQ) and soliciting behavior. In contrast, low scores of LQ and no soliciting behavior were observed in all of the 5 mg P-treated rats, even if the SL, POAL, or DRL was made. These results suggest that the septum, the preoptic area, and the dorsal raphe nucleus are not essential for the female sexual behavior-inhibiting mechanisms of progesterone.

Animals↗
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↗
PubMedDate not supplied

[The restructuring of the neuronal activity of the lateral hypothalamic preoptic area during the development of sleep].

Activity of neurons of hypothalamic lateral preoptic area was studied in cats during wakefulness, drowsiness and slow-wave sleep. It was shown that development of sleep was accompanied by changes either in frequency and pattern or only in frequency of pulse activity. Neurons which increased their firing rate retained their initial activity pattern characteristic for wakefulness (continuously arrhythmic or burst firing) throughout all sleep stages. The majority of neurons which decreased their firing frequency changed their pattern of activity during drowsiness or SWS. Continuously arrhythmic activity changed for a mixed-type (combination of single-pulse and burst discharges), and mixed-type activity changed for bursting. During SWS substantial part of neurons displayed changes in activity which were phased-locked with sleep spindles. The results support the existence of somnogenic neuronal populations in the preoptic area which participate in the central mechanisms of transition from wakefulness to sleep and formation of the slow-wave phase.

Animals↗
PubMed1986

Morphine inhibits electrically stimulated noradrenaline release from slices of rat medial preoptic area.

Experiments were undertaken to investigate whether the release of noradrenaline (NA) in the preoptic area of female rats is modulated by opiate mechanisms. Slices (300 microns) of preoptic area were incubated individually after loading with 3H-NA and then subjected to electric field stimulation. Morphine (10 microM) significantly reduced the amount of NA released in response to electrical stimulation, an effect that was completely prevented by simultaneous exposure to equimolar naloxone. This inhibitory action of morphine was not dependent upon prior exposure to oestrogen.

Animals↗
PubMed2003

Estradiol control of expression and levels of estradiol-binding proteins in the medial preoptic area, medial hypothalamus and pituitary.

The brains of mammals have at least three estradiol-binding proteins: estradiol receptor-alpha (ERalpha), ERbeta, and sex hormone-binding globulin (SHBG). In this study we compare the effects of estradiol treatment on the expression of mRNA for these three estradiol-binding proteins in two reproductively important brain areas, the medial preoptic area-anterior hypothalamus (MPOA-AH) and medial hypothalamus (MH) as well as in the hippocampus in ovariectomized rats, using the reverse transcriptase-polymerase chain reaction (RT-PCR). We also used surface-enhanced laser desorption ionization time of flight (SELDI-TOF) mass spectrometry (MS) to analyze the effects of estradiol in ovariectomized rats on SHBG levels in the MPOA-MH as well as the neurohypophysis. In vivo estradiol treatment in ovariectomized rats eliminated or significantly reduced expression of all three estradiol-binding proteins in both the MPOA-AH and MH. This change in ERalpha, ERbeta, and SHBG expression did not occur in the hippocampus. Both Northern blot and DNA sequence analysis confirmed the results of the RT-PCR for SHBG. SELDI-TOF MS analysis demonstrated that in vivo estradiol treatments resulted in dramatically decreased levels of SHBG in the hypothalamus and that a reduction in SHBG mRNA by estradiol treatment also resulted in a reduction in SHBG protein levels. Estradiol treatment also eliminated detectable SHBG from the neurohypophysis, suggesting that estradiol controls SHBG levels in this release site. That in vivo estradiol treatments had the same inhibitory effects on mRNA levels for SHBG and both ERs suggests similar translational control mechanisms for all three steroid-binding proteins in the brain. That estradiol treatments also reduced pituitary SHBG suggests that such treatment releases SHBG from the neurohypophysis.

Animals↗
PubMed2005

Progesterone-receptive beta-endorphin and dynorphin B neurons in the arcuate nucleus project to regions of high gonadotropin-releasing hormone neuron density in the ovine preoptic area.

Progesterone inhibits gonadotropin-releasing hormone (GnRH) secretion through interneuronal systems located in the mediobasal hypothalamus in ewes. Endogenous opioid peptides are implicated in this inhibition of GnRH secretion. The distributions of endogenous opioid peptides are known to overlap with progesterone receptors (PR) in the arcuate nucleus. We investigated whether PR is expressed by beta-endorphin and dynorphin B neurons in the arcuate nucleus and if a subset of double-labeled cells projects to the preoptic area where most GnRH neurons are detected. Injection of a retrograde tracer, Fluorogold, into the rostral preoptic area was performed in ovariectomized ewes pretreated with estrogen and progesterone. Brain sections were processed using double immunocytochemistry. Only brains of ewes with an injection site encompassing at least 80 GnRH neurons were processed for PR and then either beta-endorphin or dynorphin B immunocytochemistry. Antigen retrieval is essential for PR detection but causes Fluorogold to fade. Thus, quantitative analysis was performed on photographs taken before and after antigen retrieval. We found that 25-30% of PR-containing neurons, 20% of beta-endorphin cells and 22% of dynorphin B neurons in the arcuate nucleus project toward the preoptic area. From the PR/beta-endorphin double-labeled cells that represent 25 and 36% of PR and beta-endorphin cells, respectively, 35% were labeled with Fluorogold. From the PR/dynorphin B double-labeled cells that account for 39 and 62% of PR and dynorphin B neurons, respectively, 26% contained Fluorogold. These data strongly support the hypothesis that progesterone acts in the arcuate nucleus through beta-endorphin and dynorphin B neurons to affect preoptic area GnRH neurons.

Animals↗
PubMed1988

Microinjection of cis-flupenthixol, a dopamine antagonist, into the medial preoptic area impairs sexual behavior of male rats.

Systemically administered dopamine agonists have been shown to facilitate copulation in male rats. Microinjection of the dopamine agonist apomorphine into the medial preoptic area has also been reported to facilitate sexual behavior. The present experiments investigated the effects of medial preoptic microinjections of the dopamine antagonist cis-flupenthixol on male rat copulatory behavior. Fewer males initiated copulation and fewer ejaculated following flupenthixol administration. Those males that did ejaculate following flupenthixol injections had fewer ejaculations and longer interintromission intervals. Flupenthixol also antagonized the facilitative effects of apomorphine injections into the medial preoptic area. Flupenthixol and apomorphine produced only minor alterations in noncopulatory behaviors. The results suggest that dopamine receptors within the medial preoptic area are important in the regulation of masculine sexual behavior in the rat.

Animals↗
PubMed1983

Adrenaline turnover rates in the medial preoptic area and mediobasal hypothalamus in relation to the release of luteinizing hormone in female rats.

The turnover rates of adrenaline in the medial preoptic area and mediobasal hypothalamus, areas which, respectively, include the cell bodies and terminals of luteinizing hormone-releasing hormone neurons, have been measured in female rats on pro-oestrus, the day of the preovulatory surge of luteinizing hormone, and on dioestrus, the preceding day. A rise in the rate of turnover was found in the medial preoptic area coinciding with the surge of luteinizing hormone in the late afternoon of pro-oestrus; the rate of turnover at this time was higher than at the same time on dioestrus. No changes in turnover rate were found in the mediobasal hypothalamus within either of these days. The results indicate that the adrenaline-containing projections to the preoptic area may be actively involved in the production of the spontaneous preovulatory surge of luteinizing hormone in rats.

Animals↗
PubMed1990

Metabolic adjustment induced by exposure to elevated ambient temperature is impaired in rats bearing lesions in the preoptic area.

Metabolic adjustment was studied in rats with bilateral electrolytic lesions in the preoptic area which were exposed to heat (34 degrees C) and to normal temperature (25 degrees C) for 60 days. The metabolic rate measured at neutral temperature (29 degrees C) in preoptic-lesioned rats living at 25 degrees or 34 degrees C was reduced to 80% the rate of sham-operated controls. The increase in metabolic rate induced by heat (30 min at 34 degrees or 37 degrees C) in preoptic-lesioned rats, living at 25 degrees C, was markedly reduced to 10% the rate of sham-operated controls living at 25 degrees C. In preoptic-lesioned rats, the increased metabolic rate induced by heat exposure (34 degrees or 37 degrees C) was impaired, regardless of the living ambient temperature (25 degrees or 34 degrees C) of the animal. These data demonstrate the participation of the preoptic area in heat-induced increased oxygen consumption and provide additional evidence for its role in the integration of thermal inputs with energy-linked metabolic processes.

Adaptation, Physiological↗
PubMedDate not supplied

Permanent effects of postnatal administration of beta-adrenergic ligands on the volume of sexually dimorphic nucleus of the preoptic area (SDN-POA) in rats.

BACKGROUND: beta-adrenergic ligands have been shown to influence sexual differentiation of the brain. In the present study we document that short postnatal treatment with beta-adrenergic agonists or antagonists may permanently reverse the morphological sex of the brain, as judged by the volume of sexually dimorphic nucleus of the preoptic area (SDN-POA). Female rats treated by beta(2)-adrenergic stimulating ligands exhibit an increased, male type SDN-POA volume while male rats treated by beta1-adrenergic antagonists show a decreased, female type of SDN-POA volume. OBJECTIVES: To analyze the volume of SDN-POA of adult rats after postnatal administration of betaadrenergic ligands. METHODS: From the second day of life, over 5 consecutive days, all the neonates were injected subcutaneously with the following drugs: isoproterenol, salbutamol, metoprolol alprenolol or saline. SDN-POA volumes were estimated planimetrically on serial brain slides. RESULTS: In male rats the mean volume of SDN-POA was 9.97 +/- 1.66 x 10(-3) mm(3), in female rats the respective volume reached 4.02 +/- 1.26 x 10(-3) mm(3) only and was 2.5 times lower, the difference being highly statistically significant. Postnatal administration of isoproterenol remained without effect in male rats but diminished the SDN-POA volume in female rats, thus increasing the sexual dimorphism. The disappearance of sexual dimorphism was noted in rats treated postnatally with salbutamol. This effect was due to the increase in SDN-POA volumes in female rats, up to 9.81 +/- 2.64 x 10(-3) mm(3), the levels approaching the male type of POA differentiation. Postnatal alprenolol treatment influenced the sexual dimorphism of the brain by decreasing the SDN-POA volume reached by adult males. In fact, in rats treated postnatally with alprenolol, the volume of the nucleus reached only 4,44 +/- 1,61 x 10(-3) mm(3), being not statistically different from female nuclei. The effect of metoprolol pretreatment was similar to alprenolol. Male volumes of SDN-POA were restored both by isoproterenol and salbutamol in metoprolol pretreated rats and by isoproterenol only in alprenolol treated rats. CONCLUSION: It appears that inhibition of beta(1)-adrenergic pathway is able to shut off the physiologic mechanisms of male differentiation of SDN-POA, and the subsequent beta(2)-adrenergic stimulation activates an alternative mechanism of masculinization. beta(2)-adrenergic signal is able to masculinize rat preoptic area in females as well. From the presented data it may be concluded that beta adrenoreceptors participate in sexual differentiation of preoptic area in rats and the modulation of their activity in postnatal period permanently influences the morphology of the sexually differentiated nucleus of the preoptic area.

Adrenergic beta-Agonists↗
PubMed1999

Effects of microinjections of triazolam into the ventrolateral preoptic area on sleep in the rat.

In view of interest in the ventrolateral preoptic area (VLPO), based on FOS protein accumulation during sleep as well as its output pathways to areas involved in sleep regulation, we have examined the effects of microinjections of triazolam into the VLPO. It was found that two doses of triazolam, noted previously to enhance sleep when injected into the medial preoptic area, had no significant effect on sleep or core temperature when administered into the VLPO. Although these data do not bear on the possibility that the VLPO is involved in physiological sleep regulation, they suggest that it is not a site of the pharmacologic action of hypnotic benzodiazepines.

Animals↗
PubMed2005

Dopamine, the medial preoptic area, and male sexual behavior.

The medial preoptic area (MPOA), at the rostral end of the hypothalamus, is important for the regulation of male sexual behavior. Results showing that male sexual behavior is impaired following MPOA lesions and enhanced with MPOA stimulation support this conclusion. The neurotransmitter dopamine (DA) facilitates male sexual behavior in all studied species, including rodents and humans. Here, we review data indicating that the MPOA is one site where DA may act to regulate male sexual behavior. DA agonists microinjected into the MPOA facilitate sexual behavior, whereas DA antagonists impair copulation, genital reflexes, and sexual motivation. Moreover, microdialysis experiments showed increased release of DA in the MPOA as a result of precopulatory exposure to an estrous female and during copulation. DA may remove tonic inhibition in the MPOA, thereby enhancing sensorimotor integration, and also coordinate autonomic influences on genital reflexes. In addition to sensory stimulation, other factors influence the release of DA in the MPOA, including testosterone, nitric oxide, and glutamate. Here we summarize and interpret these data.

Animals↗