Effect of microinjection of muscimol into the dorsomedial or paraventricular hypothalamic nucleus on air stress-induced neuroendocrine and cardiovascular changes in rats

Stotz-Potter, E. H.; Morin, Stéphanie; DiMicco, Joseph A.

doi:10.1016/s0006-8993(96)01011-6

Cited by 122 publications

(116 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The effects of muscimol microinjected into the PVN on blood pressure have been reported in many studies, and the results have been considerably variable. In some reports, there is little change in MAP following muscimol into the PVN, while in others a considerable change in MAP has been reported (1,15,32,34,41,(43)(44)(45)(46). Indeed, in our earlier study, we did not detect any effect of muscimol on blood pressure following its microinjection into the PVN (10).…”

Section: Discussioncontrasting

confidence: 48%

“…Indeed the changes in blood flow obtained following stimulation of the PVN resemble the responses observed during the defense response (14). However, the role of the PVN in mediating the cardiovascular components of the defense reaction elicited by stress has been challenged by DiMicco and colleagues (12,35,45,46) who argue that it is the neighboring dorsomedial hypothalamic nucleus that is the critical site for the cardiovascular responses initiated by stress. By contrast, there is strong evidence for a critical role of the PVN in the cardiovascular responses to various physiological stimuli, such as changes in blood volume and osmolality (5,22,23,38,44).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia

Chen¹,

Dworak²,

Wang³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

In the present study, we investigated whether the PVN is a key region in the mesenteric vasoconstriction that normally accompanies an increase in core body temperature. Anesthetized rats were monitored for blood pressure, heart rate, mesenteric blood flow, and vascular conductance. In control rats, elevation of core body temperature to 41°C had no significant effect on blood pressure, increased heart rate, and reduced mesenteric blood flow by 21%. In a separate group of rats, muscimol was microinjected bilaterally (1 nmol/side) into the PVN. Compared with the control group, there was no significant difference in the blood pressure and heart rate responses elicited by the increase in core body temperature. In contrast to control animals, however, mesenteric blood flow did not fall in the muscimol-treated rats in response to the elevation in core body temperature. In a separate group, in which muscimol was microinjected into regions outside the PVN, elevating core body temperature elicited the normal reduction in mesenteric blood flow. The results suggest that the PVN may play a key role in the reflex decrease in mesenteric blood flow elicited by hyperthermia.reflex mesenteric blood flow; increased core body temperature CARDIOVASCULAR RESPONSES TO changes in body temperature include marked changes in sympathetic nerve activity and blood flow. In response to hyperthermia, for example, there are increases in splanchnic, renal, splenic, and lumbar sympathetic nerve activity (25,28), resulting in vasoconstriction of the respective vascular beds. In contrast, hyperthermia elicits vasodilation in the skin vasculature, and in the rat tail vasodilation also occurs (21, 24); the tail is a major thermoregulatory organ in the rat. These changes contribute to the redistribution of the blood flow during hyperthermia such that blood is redirected from the warm internal environment in visceral organs to the peripheral vasculature where heat can be dissipated.The alterations in blood flow, mediated by changes in sympathetic nerve activity, involve the central nervous system. The sites in the brain that are likely to be involved in mediating the responses include the sympathetic premotor nuclei located in the hypothalamus and brain stem. These regions contain neurons that directly project to the sympathetic preganglionic motor neurons located in the intermediolateral cell column of the thoracolumbar spinal cord.Within the forebrain, the hypothalamic paraventricular nucleus (PVN) is a key integrative site involved in hormonal, endocrine, and neural control. The PVN is composed of different neuronal subgroups subserving different functions, including cardiovascular regulation. The PVN is one of the small number of premotor nuclei present in the brain (4, 47). There are neurons in the PVN that project to regions of the spinal cord where sympathetic preganglionic neurons are located and thereby can directly influence sympathetic activity (8,40,48). In addition to the spinal projecting neurons present in the PVN, there are neuronal sub...

show abstract

Section: Discussioncontrasting

confidence: 48%

mentioning

confidence: 99%

Role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia

Chen¹,

Dworak²,

Wang³

et al. 2008

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…Thus, there is good evidence that the observed changes in ACTH release induced by temazepam after stressor exposure are due to an action of the benzodiazepine at the brain level. In this context, different lines of evidence suggest that temazepam might act on GABA A receptors expressed by parvocellular PVN neurons (Makara and Stark, 1974;Olschowka, 1987;Calogero et al, 1988;Meister et al, 1988;Hillhouse and Milton, 1989;Tsagarakis et al, 1990;Stotz-Potter et al, 1996). Unfortunately, there are no tools available to allow for measurement of portal blood concentrations of AVP and CRH in freely moving rats.…”

Section: Temazepam Triggers Intra-pvn Release Of Avp T Welt Et Almentioning

confidence: 99%

Temazepam Triggers the Release of Vasopressin into the Rat Hypothalamic Paraventricular Nucleus: Novel Insight into Benzodiazepine Action on Hypothalamic–Pituitary–Adrenocortical System Activity During Stress

Welt

Engelmann

Renner

et al. 2006

Neuropsychopharmacol

View full text Add to dashboard Cite

We investigated the influence of a representative classical benzodiazepine on the regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis activity both under basal conditions and stress. Adult male Wistar rats were intravenously administered with temazepam (0.5, 1, and 3 mg/kg body weight) and plasma concentrations of corticotropin (ACTH) and vasopressin (AVP) were measured in blood samples collected via chronically implanted jugular venous catheters. Simultaneously, the release of AVP within the hypothalamic paraventricular nucleus (PVN) was monitored via microdialysis. Plasma AVP levels remained unaffected by the different treatment conditions. Temazepam blunted the stressor exposure-induced secretion of ACTH in a dose-dependent manner. Concurrently, and also in a dose-dependent manner temazepam enhanced the intra-PVN release of AVP, known to originate from magnocellular neurons of the hypothalamic neurohypophyseal system. Furthermore, temazepam did not affect the in vitro secretion of ACTH from the adenohypophyseal cells. Taken together, the results of this study suggest that temazepam modulates the central nervous regulation of the HPA axis by altering intra-PVN AVP release. An increasingly released AVP of magnocellular origin seems to provide a negative tonus on ACTH secretion most probably via inhibiting the release of ACTH secretagogues from the median eminence into hypophyseal portal blood.

show abstract

“…The hippocampus (CA1-3 and subiculum) has been implicated in the mechanism of glucocorticoid negative feedback (for review, see Jacobson and Sapolsky, 1991;Herman et al, 1995). The DM H has been implicated in mediating cardiovascular responses to stress (De Novellis et al, 1995;Stotz-Potter et al, 1996b), as well as a possible role in stress-induced release of ACTH (Stotz-Potter et al, 1996a). Both brain regions showed a significant increase in c-fos expression after handling with no further increases after fighting.…”

Section: Stress Neurocircuits: Neuroendocrine Regulationmentioning

confidence: 99%

Social Stress in Hamsters: Defeat Activates Specific Neurocircuits within the Brain

1997

View full text Add to dashboard Cite

During an agonistic encounter, subordinate male hamsters display defensive and submissive postures and show increased secretion of glucocorticoids, whereas dominant males do not. To determine whether specific neuronal pathways are activated during the behavioral and neuroendocrine responses of subordinate males, expression of c-fos mRNA within the brains of subordinate males was compared with the pattern in dominant males after fighting. After 1 week of handling, pairs of hamsters were either swapped between cages (handled control males), or were allowed to interact for 30 min [dominant (DOM) males and subordinate (SUB) males]. A second group of control animals that received no handling or social stimulation (unhandled control males) were also included. After testing, all animals were killed by decapitation, their brains were removed for c-fos in situ hybridization, and trunk blood was collected for analysis of plasma cortisol and corticosterone levels. Exposure of males to their partner's cage for 30 min resulted in increased expression of c-fos mRNA in multiple brain regions. In addition, fighting increased c-fos expression in the medial amygdaloid nucleus of both DOM and SUB males as well as having more selective effects. In DOM males, c-fos expression was elevated within the supraoptic nucleus of the hypothalamus. In SUB males, c-fos expression increased within a multitude of brain areas, including cingulate cortex, lateral septum, bed nucleus of the stria terminalis, medial preoptic area, several hypothalamic nuclei, central amygdaloid nucleus, amygdalohippocampal area, dorsal periaqueductal gray, dorsal raphe, cuneiform nucleus, and locus coeruleus. These findings are discussed in relation to neurocircuits associated with behavioral arousal and stress.

show abstract

Effect of microinjection of muscimol into the dorsomedial or paraventricular hypothalamic nucleus on air stress-induced neuroendocrine and cardiovascular changes in rats

Cited by 122 publications

References 20 publications

Role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia

Role of the hypothalamic PVN in the reflex reduction in mesenteric blood flow elicited by hyperthermia

Temazepam Triggers the Release of Vasopressin into the Rat Hypothalamic Paraventricular Nucleus: Novel Insight into Benzodiazepine Action on Hypothalamic–Pituitary–Adrenocortical System Activity During Stress

Social Stress in Hamsters: Defeat Activates Specific Neurocircuits within the Brain

Contact Info

Product

Resources

About