Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

Cham, Joo Lee; Badoer, Emilio

doi:10.1152/ajprenal.00488.2007

Cited by 17 publications

(24 citation statements)

References 31 publications

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“…Neurons in the PVN are activated by increases in ambient temperature, including those that influence sympathetic nerve activity (3,7,9,27), suggesting a role for the PVN in temperature regulation. The present study, together with our more recent work showing that inhibition of neuronal function within the PVN prevented the hyperthermia-induced reduction in renal and mesenteric blood flows, provides direct evidence that the PVN plays a key role in the cardiovascular thermoregulatory responses (8,10). This does not exclude other brain regions contributing to the reflex renal vasoconstriction elicited by hyperthermia.…”

Section: Discussionsupporting

confidence: 59%

“…Our hypothesis is that the PVN is the key site, since it has a dense concentration of ANG II type 1 receptors and that inhibition of the PVN prevents the reflex vasoconstriction in renal and mesenteric vasculature (1,8,10). In the present study, therefore, we investigated the effect of microinjection of the ANG II type 1 receptor antagonist, losartan, directly into the PVN on the reflex reduction in renal blood flow induced by elevating body core temperature in rats.…”

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confidence: 99%

“…More recently, we have found that the PVN is essential for the normal reflex reduction in renal and mesenteric blood flows induced by hyperthermia (6,8,10). The PVN is one of the few sympathetic premotor nuclei present in the brain; that is, it contains neurons that project directly to sympathetic preganglionic motor neurons in the intermediolateral cell column of the thoracolumbar spinal cord (9, 32, 36).…”

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confidence: 99%

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AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

Chen

Liu

Badoer

2011

American Journal of Physiology-Regulatory, Integrative and Comp

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Increasing body core temperature reflexly decreases renal blood flow (RBF), and the hypothalamic paraventricular nucleus (PVN) plays an essential role in this response. ANG II in the brain is involved in the cardiovascular responses to hyperthermia, and ANG II receptors are highly concentrated in the PVN. The present study investigated whether ANG II in the PVN contributes to the cardiovascular responses elicited by hyperthermia. Rats anesthetized with urethane (1-1.4 g/kg iv) were microinjected bilaterally into the PVN (100 nl/side) with saline (n ϭ 5) or losartan (1 nmol/100 nl) (n ϭ 7), an AT1 receptor antagonist. Body core temperature was then elevated from 37°C to 41°C and blood pressure (BP), heart rate (HR), RBF, and renal vascular conductance (RVC) were monitored. In separate groups losartan (n ϭ 4) or saline (n ϭ 4) was microinjected into the PVN, but body core temperature was not elevated. Increasing body core temperature in control rats elicited significant decreases in RBF (Ϫ48 Ϯ 5% from a resting level of 14.3 Ϯ 1.4 ml/min) and MVC (Ϫ40 Ϯ 4% from a resting level of 0.128 Ϯ 0.013 ml/min·mmHg), and these effects were entirely prevented by pretreatment with losartan. In rats in which body core temperature was not altered, losartan microinjected into the PVN had no significant effects on these variables. The results suggest that endogenous ANG II acts on AT1 receptors in the PVN to mediate the reduction in RBF induced by hyperthermia.hypothalamus; body temperature; brain; angiotensin ii THERMOREGULATION IS A VITAL, fundamental physiological function that enables the body to defend itself from external and internal temperature changes. There are a number of cardiovascular mechanisms that help do this; for example, during hyperthermia in humans, blood flow is redirected from the viscera (e.g., renal and splanchnic regions) to the skin so that the body may dissipate heat. Such responses are brought about by altering sympathetic nerve activity. Increasing sympathetic nerve activity to the vasculature of visceral organs like the kidneys and mesentery is important since failure to adequately vasoconstrict these in response to hyperthermia can cause a dramatic reduction in cardiac output and the resultant lifethreatening sequelae of heat stroke (22-23).The hypothalamus, in particular, plays a key role in thermoregulation and the hypothalamic paraventricular nucleus (PVN), located adjacent to the third ventricle in the forebrain, is an important integrative site involved in hormonal, endocrine, and peripheral neural control.Activation of the PVN can cause a pronounced alteration in blood pressure, sympathetic neural outflows, and hemodynamic responses (5-6, 11, 21, 31). There are several lines of evidence supporting a role of the PVN in the cardiovascular responses elicited during thermoregulation: 1) the PVN contains neurons that project to areas important for thermoregulation, such as the brown adipose tissue, the tail (in the rat), kidney, and gut (19, 26, 30, 34 -35); 2) the PVN can influence sympathetic ne...

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Section: Discussionsupporting

confidence: 59%

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confidence: 99%

mentioning

confidence: 99%

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AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

Chen

Liu

Badoer

2011

American Journal of Physiology-Regulatory, Integrative and Comp

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“…In a recent study, we found that the PVN also plays a critical role in the reflex reduction in renal blood flow elicited by an increase in core body temperature (10). This effect was also specific to the PVN.…”

Section: Discussionmentioning

confidence: 69%

“…More recently we have provided strong evidence indicating that the PVN is essential for the reflex vasoconstriction of the renal vasculature induced by an elevation in core body temperature (10), indicating that the hypothalamic PVN is functionally important in the cardiovascular reflex responses of the renal vasculature elicited by hyperthermia. Whether the role of the PVN is confined to the renal vasculature or whether the PVN contributes to the decrease in mesenteric blood flow that also accompanies an increase in core body temperature is not known.…”

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confidence: 95%

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

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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...

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Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic neuronal activation

Drummond

Campos

Lima

et al. 2020

Pflugers Arch - Eur J Physiol

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This study aimed to evaluate the physical exercise-induced neuronal activation in brain nuclei controlling thermoregulatory responses in hypertensive and normotensive rats. Sixteen-week-old male normotensive Wistar rats (NWRs) and spontaneously hypertensive rats (SHRs) were implanted with an abdominal temperature sensor. After recovery, the animals were subjected to a constant-speed treadmill running (at 60% of the maximum aerobic speed) for 30 min at 25°C. Core (T core ) and tail-skin (T skin ) temperatures were measured every minute during exercise. Ninety minutes after the exercise, the rats were euthanized, and their brains were collected to determine the c-Fos protein expression in the following areas that modulate thermoregulatory responses: medial preoptic area (mPOA), paraventricular hypothalamic nucleus (PVN), and supraoptic nucleus (SON). During treadmill running, the SHR group exhibited a greater increase in T core and an augmented threshold for cutaneous heat loss relative to the NWR group. In addition, the SHRs showed reduced neuronal activation in the mPOA (< 49.7%) and PVN (< 44.2%), but not in the SON. The lower exercise-induced activation in the mPOA and PVN in hypertensive rats was strongly related to the delayed onset of cutaneous heat loss. We conclude that the enhanced exercise-induced hyperthermia in hypertensive rats can be partially explained by a delayed cutaneous heat loss, which is, in turn, associated with reduced activation of brain areas modulating thermoregulatory responses.

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Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

Cited by 17 publications

References 31 publications

AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

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

Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic neuronal activation

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Hypothalamic paraventricular nucleus is critical for renal vasoconstriction elicited by elevations in body temperature

Cited by 17 publications

References 31 publications

AT1 receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

AT1 receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

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

Impaired thermoregulation in spontaneously hypertensive rats during physical exercise is related to reduced hypothalamic neuronal activation

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AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats

AT₁ receptors in the paraventricular nucleus mediate the hyperthermia-induced reflex reduction of renal blood flow in rats