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PubMed1983

Thermosensitive characteristics of a preoptic area neuron recorded over a 20 day period in the rabbit.

The thermosensitive characteristics of a single preoptic area neuron were monitored over a period of twenty days from a rabbit fitted with chronic recording electrodes. No demonstrable daily changes were detected in either the basal firing rate or the mean interspike interval during control recordings. Only minor daily variations were observed in thermosensitivity (impulses-second/degree C) and in the interspike interval coefficient of variation for this neuron in response to preoptic heating and cooling with a water-perfused thermode. When measured during early morning, early afternoon and at late night, thermosensitivity remained constant and showed no apparent circadian rhythm. The results from this single thermosensitive preoptic area neuron suggest that in spite of circadian rhythms of body temperature and other physiological parameters, some thermoregulatory neurons retain fixed temperature sensitive properties under conditions of stable ambient temperature.

Action Potentials↗
PubMed1995

Salmon GnRH synthesis in the preoptic area and the ventral telencephalon is activated during gonadal maturation in female Masu Salmon.

Changes in salmon gonadotropin-releasing hormone (sGnRH) synthetic activity in the brain during gonadal maturation were examined by in situ hybridization in 2-year-old female masu salmon. Oncorhynchus masou. During gonadal maturation, the numbers of neurons expressing sGnRH mRNA increased in the preoptic area and the ventral telencephalon, but not in the olfactory bulbs and the terminal nerve ganglion. The numbers of silver grains per neuron also increased in the preoptic area and the ventral telencephalon. These results indicate that sGnRH has multiple physiological functions according to the location of the neurons in the brain; neurons in the preoptic area and the ventral telencephalon are involved in gonadal maturation possibly by stimulating gonadotropin synthesis and release, whereas neurons in the olfactory bulbs and the terminal nerve ganglion may have different roles.

Animals↗
PubMed1989

Dynorphin A (1-13), microinjected into the preoptic area, stimulates water intake in rats.

The effects of dynorphin A (1-13) (DYN), injected into the preoptic area, was investigated on water intake in rats. DYN at both doses of 2 and 10 nmoles significantly increased water intake for two and four hours after the injection in a dose related fashion. However, no significant change was observed in food intake. Naloxone pretreatment (0.3 mg/kg, s.c.) completely attenuated the DYN-induced stimulation of water intake. The present studies suggest that DYN in the preoptic area may play an important role in the regulation of drinking behavior, but have no effect on food intake.

Animals↗
PubMed2000

Role of the lateral preoptic area in sleep-related erectile mechanisms and sleep generation in the rat.

Penile erections are a characteristic phenomenon of paradoxical sleep (PS), or rapid eye movement sleep. Although the neural mechanisms of PS-related erections are unknown, the forebrain likely plays a critical role (Schmidt et al., 1999). The preoptic area is implicated in both sleep generation and copulatory mechanisms, suggesting it may be a primary candidate in PS erectile control. Continuous recordings of penile erections, body temperature, and sleep-wake states were performed before and up to 3 weeks after ibotenic acid lesions of the preoptic forebrain in three groups of rats. Neurotoxic lesions involving the medial preoptic area (MPOA) and anterior hypothalamus (n = 5) had no significant effects on either erectile activity or sleep-wake architecture. In contrast, bilateral lesions of the lateral preoptic region, with (n = 4) or without (n = 5) MPOA involvement, resulted in a significant decrease in the number of erections per hour of PS, number of PS-related erections, and PS phases exhibiting an erection. Lesion analysis revealed that the candidate structures for PS erectile control include both the lateral preoptic area (LPOA) and ventral division of the bed nucleus of the stria terminalis; however, lesions of the LPOA were the most effective in disrupting PS erectile activity. LPOA lesioning also resulted in a long-lasting insomnia, characterized by the significant increase in wakefulness and decrease in slow wave sleep (SWS). PS architecture and waking-state erections remained unchanged after lesion in all groups. These data identify an essential role of the LPOA in both PS-related erectile mechanisms and SWS generation. Moreover, higher erectile mechanisms appear to be context-specific because LPOA lesioning selectively disrupted PS-related erections while leaving waking-state erections intact.

Animals↗
PubMed1992

Brown adipose tissue temperature responses following electrical stimulation of ventromedial hypothalamic and lateral preoptic areas or after norepinephrine infusion to Long Evans or Sprague-Dawley rats.

Thermoregulatory (brown adipose tissue temperature) experiments were conducted in age-matched anesthetized, male Sprague-Dawley and Long Evans rats kept at 37 degrees C given unilateral electrical stimulation of the ventromedial hypothalamic nucleus or the lateral preoptic area or after intravenous infusion of norepinephrine HCl (50 micrograms/kg total dose). Unilateral electrical stimulation (0.5 ms pulses of 250 microA at 50 Hz for 30 s) of the ventromedial nucleus or lateral preoptic area caused significant rises (greater than 0.6 degrees C) of intrascapular brown adipose tissue temperature in the Long Evans group only. Norepinephrine infusion (0.1 ml/min for 10 min), or intravenous bolus injection of propranolol HCl (2.5 mg/kg) caused significant yet similar increases (greater than 1.0 degrees C) and decreases (greater than -0.3 degrees C), respectively, of intrascapular brown adipose tissue temperature from pre-administration control temperatures in both Long Evans and Sprague-Dawley groups. The results demonstrate that intrascapular brown adipose tissue sensitivity towards exogenous norepinephrine or propranolol administration is similar between Sprague-Dawley and Long Evans rats acclimated to 21 degrees C as determined by increases in temperature in the intrascapular brown adipose tissue pad. However, intrascapular brown adipose tissue thermogenesis of 21 degrees C-acclimated Long Evans rats is also activated after CNS electrical stimulation of the ventromedial nucleus or lateral preoptic area, an activation not seen in Sprague-Dawley rats suggestive that the latter group has some inhibition of neural pathways that activate brown adipose tissue thermogenesis.

Adipose Tissue, Brown↗
PubMed2001

Increased synaptic input to gonadotropin releasing hormone cells in preoptic area grafts that support reproductive development in female hypogonadal mice.

Ultrastructural studies have established that gonadotropin releasing hormone (GnRH) neuronal cell bodies receive sparse synaptic input compared to other neuronal cell types. In the present studies, immunocytochemistry for the presynaptic marker synaptophysin, coupled with confocal microscopy, was employed to evaluate whether there was a difference in synaptic input to GnRH cells within preoptic area grafts (hypogonadal, HPG; preoptic area, POA) in hypogonadal female mice that did or did not show ovarian development. GnRH cells in HPG/POA mice with ovarian development exhibited significantly higher numbers of synaptophysin immunoreactive (syn-IR) appositions as compared with HPG/POA mice without ovarian development. This suggests that synaptic input to the grafted GnRH cells is important for the correction of reproductive functions in HPG/POA mice. Following mating, Fos immunoreactivity was present in several GnRH cells in HPG mice with successful POA grafts, indicating the establishment of neuronal projections conveying somatosensory information to the GnRH cells in these mice. The presence of a higher number of syn-IR appositions to GnRH cells in the successful grafts supports this hypothesis.

Animals↗
PubMed1988

Neurogenic stimuli alter preoptic area and amygdala unit activity: central effects of olfactory projections on paraventricular nucleus units.

Unit responses were recorded in the preoptic area and amygdala of conscious male rats during exposure to stressful neurogenic stimuli. Olfactory stimulation elicited increases in preoptic area activity on all occasions and also increased activity in the intercalating, medial, and basomedial nuclei of the amygdala, but not in other regions. Acoustic stimulation had less specific effects, even inhibiting unit activity in the central amygdala. A separate series of experiments using urethane-anesthetized rats was carried out to examine the effects of electrical stimulation of the medial amygdala and olfactory tubercle on single-unit activity within the hypothalamic paraventricular nucleus. Inhibition was the predominant response following olfactory tubercle stimulation while excitatory responses predominated following stimulation of the medial amygdala. This was the case particularly for those paraventricular nucleus units identified as projecting to the median eminence (P less than 0.005 vs unidentified cells). The results obtained may be related to the neural regulation of adrenocortical activity as well as higher central nervous activity and have been discussed within these contexts.

Acoustic Stimulation↗
PubMed1994

Expression of Fos-like immunoreactivity in the preoptic area of maternally behaving virgin and postpartum rats.

This study uses Fos immunocytochemistry to show that the medial preoptic area and ventral bed nucleus of the stria terminalis are activated in maternally behaving female rats. In Experiment 1, virgin female rats that showed maternal behavior toward pups had more cells in these regions that expressed Fos-like immunoreactivity than did virgin females that were not maternally responsive. In Experiment 2, postpartum rats that were exposed to pups and showed maternal behavior had more Fos-labeled cells in these regions than did postpartum rats exposed to candy. Evidence also indicated that functional modifications in the medial amygdala were related to the changes in Fos expression observed in the preoptic area and ventral bed nucleus of the stria terminalis.

Amygdala↗
PubMed1985

Afferent and efferent connections of the medial preoptic area in the rat: a WGA-HRP study.

Afferent and efferent connections of the medial preoptic area including medial preoptic nucleus (MP) and periventricular area at the MP level were examined using WGA-HRP as a marker. Injections were performed by insertion of micropipette containing (1) small amount of HRP powder or (2) dryed HRP solution for 24 to 48 hr until the fixation or for 5 min respectively. Dorsal and ventral approaches of injection micropipettes were performed and the results were compared. Previously reported reciprocal connections with lateral septum, bed nucleus of the stria terminalis, medial amygdaloid nucleus, lateral hypothalamic nucleus, paraventricular hypothalamic nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, supramammillary nucleus, central gray at the mesencephalon, raphe dorsalis, raphe medianus, and lateral parabrachial nucleus have been confirmed. In addition, we found reciprocal connections with septo-hypothalamic nucleus, amygdalo-hipocampal nucleus, subiculum, parafascicular thalamic nucleus, posterior thalamic nucleus at the caudo-ventral subdivision, median preoptic nucleus, lateral preoptic nucleus, anterior hypothalamic nucleus, periventricular area at the caudal hypothalamic level, dorsomedial hypothalamic nucleus, posterior hypothalamic nucleus, dorsal and ventral premammillary nucleus, lateral mammillary nucleus, peripeduncular nucleus, periventricular gray, ventral tegmental area, interpeduncular nucleus, nucleus raphe pontis, nucleus raphe magnus, pedunculo-pontine tegmental nucleus, gigantocellular reticular nucleus and solitary tract nucleus. The areas which had only efferent connections from MP were accumbens, caudate putamen, ventral pallidum, substantia innominata, lateral habenular nucleus, paratenial thalamic nucleus, paraventricular thalamic nucleus, mediodorsal thalamic nucleus, reuniens thalamic nucleus, median eminence, medial mammillary nucleus, subthalamic nucleus, pars compacta of substantia nigra, oculomotor nucleus, red nucleus, laterodorsal tegmental nucleus, reticular tegmental nucleus, cuneiform nucleus, nucleus locus coeruleus, and dorsal motor nucleus of vagus among which substantia innominata and median eminence were previously reported. Efferent connections to the nucleus of Darkschewitsch, interstitial nucleus of Cajal, dorsal tegmental nucleus, ventral tegmental nucleus, vestibular nuclei, nucleus raphe obsculus were very weak or abscent in the ventral approach while they were observed in dorsal approach. Previously reported afferent connections from dorsal tegmental nucleus, cuneiform nucleus, and nucleus locus ceruleus were not detected in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

Thyrotropin-releasing hormone hyperactivity in the preoptic area of spontaneously hypertensive rats.

Thyrotropin-releasing hormone (TRH) plays an important role in central cardiovascular regulation through the activation of different neurotransmitter systems at distinct extrahypothalamic sites. To study possible alterations in the TRH system in the hypertensive state, we measured TRH concentration in cerebrospinal fluid and TRH content of the preoptic area in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) by radioimmunoassay. In addition, we also measured the density of the TRH receptor in this area by a rapid filtration technique using [3H]methyl-TRH. We found a significant increase in both the TRH content (634 +/- 61 versus 350 +/- 26 pg/mg protein, SHR versus WKY; P < .01, n = 5) and density of TRH receptors without changes in affinity (Bmax, 5.0 +/- 0.1 versus 3.3 +/- 0.1 fmol/mg protein, P < .01, n = 4). An increase in TRH concentration was also found in the cerebrospinal fluid of SHR (30 +/- 3 versus 21 +/- 2 pg/mL, P < .01, n = 5), suggesting increased TRH release in the central nervous system. Northern blot analysis indicated a threefold augmented abundance of TRH precursor mRNA in the preoptic area of SHR. A polyclonal antibody raised against TRH injected peripherally or intracerebroventricularly lowered arterial blood pressure in SHR but not in WKY. In addition, long-term treatment with enalapril (5 mg/kg twice daily), which was effective in inhibiting serum angiotensin-converting enzyme activity by more than 50%, decreased arterial blood pressure and preoptic area TRH content of SHR, whereas another vasodilator, diltiazem (10 mg/kg every 8 hours), failed to produce a similar change.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed2002

A functional neuroanatomical investigation of the role of the medial preoptic area in neural circuits regulating maternal behavior.

The medial preoptic area (MPOA) is essential for normal maternal behavior in the rat. Hormone stimulation of the MPOA facilitates the behavior and lesions of the MPOA and the adjoining ventral part of the bed nucleus of the stria terminalis (vBST) disrupt the behavior. The MPOA/vBST also show increases in Fos protein expression during maternal behavior. The present study examines the larger neural circuitry within which the MPOA/vBST might operate to influence maternal behavior. Combining Fos immunocytochemistry with unilateral excitotoxic amino acid lesions or lateral knife cuts of the MPOA/vBST, we sought to identify brain regions which might be under the influence of Fos expressing neurons in the MPOA/vBST. Two brain regions, the shell of the nucleus accumbens (NAs), and the intermediate part of the lateral septum (LSi) were identified. Both the NAs and LSi exhibited elevated Fos expression during maternal behavior, while unilateral MPOA/vBST damage resulted in an ipsilateral reduction of maternal behavior-induced Fos expression in each area, suggesting that MPOA/vBST neurons modulate Fos expression and associated neural activity in both of these structures during maternal behavior. Importantly, these unilateral preoptic lesions also depressed maternal behavior-induced Fos expression in the ipsilateral MPOA and vBST. The effects of these lesions on Fos expression in the periaqueductal gray (PAG) and other brain regions are also presented.

Animals↗
PubMed1989

Estradiol-concentrating cells in the brains of hypogonadal female mice and in their intraventricular preoptic area implants.

Estradiol-concentrating cells were evaluated in the brains of hypogonadal female mice and in their intraventricular preoptic area brain grafts using autoradiography for [3H]estradiol. Normal distribution of estradiol-concentrating cells was observed in the brains of the hypogonadal mice with dense collections of these cells in the lateral septum; the medial preoptic area; the medial anterior hypothalamus; the ventromedial, arcuate, and periventricular nuclei of the hypothalamus; and the medial and cortical nuclei of the amygdala. In addition, estradiol-concentrating cells were present in all the transplants, with the estimated number of such cells in the transplants ranging from 390 to 2600. There was no correlation between numbers of estradiol-concentrating cells within the transplants and degree of reproductive recovery in the hypogonadal mice. Gonadotropin-releasing hormone (GnRH) immunocytochemistry of alternate sections revealed GnRH-immunoreactive material within the grafts and immunoreactive fibers exiting the grafts and entering the hosts' median eminence. No specific relationship between GnRH cells and estradiol-concentrating cells was evident within the grafts, nor was there any indication of identity of estrogen-concentrating cells with GnRH cells.

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↗
PubMed1991

Spinal cord substance P mediates the inhibition of gastric acid secretion induced by electrical stimulation of the preoptic area.

A possible role of spinal substance P (SP) in the mediation of signals to inhibit gastric acid secretion by central activation of the sympatho-adrenomedullary system was examined in urethane-anesthetized rats. Intrathecal (i.t.) administration of SP (1-10 nmol) inhibited vagally induced acid output. I.t. administration of spantide, a SP receptor antagonist, reduced the inhibitory effect of 3 nmol SP. I.t. administration of spantide (0.1-1 nmol) blocked the inhibition of vagally induced gastric acid output evoked by electrical stimulation of the preoptic area. Atropine, hexamethonium, phentolamine, propranolol, DL-para-chlorophenylalanine (PCPA) and 5,7-dihydroxytryptamine (5,7-DHT) were without effect. Repeated i.t. administration of 10 nmol SP produced desensitization to the SP-induced inhibitory response on gastric acid output. In these animals, electrical stimulation of the preoptic area did not inhibit vagally induced gastric acid output. These results suggest that electrical stimulation of the preoptic area excites SP-containing neurons in the spinal cord, and a resultant sympatho-adrenomedullary system-mediated inhibition of gastric acid secretion occurs.

Animals↗
PubMed1995

Functional association between the medial amygdala and the medial preoptic area in regulation of mating behavior in the male rat.

We examined the effects of combined lesions of the medial preoptic area and the medial amygdala on male copulatory behavior to understand a functional relation between these two structures in regulation of the behavior in the rat. Young adult male rats were castrated and received Silastic implants containing testosterone. After baseline copulatory tests, a unilateral medial preoptic lesion (uPOL) was made. Males with uPOL showed less intromission behavior than sham-operated males did, but none of them showed elimination of the behavior. Following the observations after the uPOL, these males were subjected to a unilateral medial amygdala lesion (uMAL) ipsilateral or contralateral to the previous uPOL. The ipsilateral uMAL did not affect copulatory behavior compared to that of sham-operated uPOL males. However, the copulatory behavior in the animals with uPOL was severely disrupted by the contralateral uMAL. These results suggest that the medial preoptic area is closely related to the medial amygdala in regulation of male rat copulatory behavior, and these areas may play a critical role in the behavior as an unitary system.

Amygdala↗
PubMed1976

Single unit recording in hypothalamus and preoptic area of estrogen-treated and untreated ovariectomized female rats.

Single unit activity was recorded with micropipettes in the medial hypothalamus and preoptic area of urethane-anesthetized ovariectomized female rats. Some females had received long-term estradiol treatment, while others had been left untreated. In the medial preoptic region and bed nucleus of the stria terminalis, estrogen-treated rats had fewer cells (compared to untreated rats) with recordable spontaneous activity, due primarily to a loss of cells with very slow firing rates. In the basomedial hypothalamus, estrogen-treated rats had more cells (than untreated rats) with recordable spontaneous activity, due primarily to an increase in the number of cells with slow firing rates. Responsiveness of neurons to somatosensory stimulation was generally low. If present it was depressed by estrogen treatment in medial preoptic area and bed nucleus of stria terminalis, while it tended to be elevated by estrogen treatment in medial anterior hypothalamus and basomedial hypothalamus. Differences in the effects of long-term systemic estrogen treatment on medial preoptic neurons compared to basomedial hypothalamus are paralledled by differences in the control of lordosis by these neurons in female rats.

Animals↗
PubMed1996

Sleep induction by microinjection of pentobarbital into the medial preoptic area in rats.

In a previous study we have shown that microinjection of the benzodiazepine hypnotic triazolam into the medial preoptic area increases sleep in rats. In order to determine whether this effect is specific to benzodiazepines, or whether it occurs with hypnotic medications from other pharmacologic classes, we have microinjected pentobarbital (1 and 100 micrograms) and vehicle in random sequence into rats and performed two hour sleep studies in the daytime with the lights on. Both doses significantly decreased sleep latency and increased nonREM and total sleep. The amount of REM sleep, REM latency, and intermittent waking time were not significantly altered. These data are consistent with the hypothesis that the medial preoptic area may be involved in sleep induction by both benzodiazepine and barbiturate hypnotic medications.

Animals↗