Lateral distribution of hypothalamic signals controlling thermoregulatory vasomotor activity and shivering in rats

Kanosue, Kazuyuki; Niwa, Ken-Ichi; Andrew, P. D.; Yasuda, Hiroki; Yanase, M.; Tanaka, Hideto; Matsumura, Kiyoshi

doi:10.1152/ajpregu.1991.260.3.r486

Cited by 27 publications

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“…Current evidence suggests that NO in the central nervous system is important in the thermoregulatory pathways mediating heat dissipation (13-15, 17, 54, 56). For example, thermal stimulation induces enhanced secretion of saliva, which is spread on the fur as a means of heat defense in rats (11,24). …”

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Activation of spinally projecting and nitrergic neurons in the PVN following heat exposure

Cham¹,

Klein²,

Owens³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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. Activation of spinally projecting and nitrergic neurons in the PVN following heat exposure. Am J Physiol Regul Integr Comp Physiol 291: R91-R101, 2006; doi:10.1152/ajpregu.00675.2005.-The present study investigated the effect of acute thermal stimulation in conscious rats on the production of Fos, a marker of increased neuronal activity, in spinally projecting and nitrergic neurons in the hypothalamic paraventricular nucleus (PVN). The PVN contains a high concentration of nitrergic neurons, as well as neurons that project to the intermediolateral cell column (IML) of the spinal cord that can directly influence sympathetic nerve activity (SNA). During thermal stimulation, the PVN is activated, but it is unknown whether spinally projecting PVN neurons and the nitrergic neurons are involved. Compared with controls, rats exposed to an environmental temperature of 39°C for 1 h had a 10-fold increase in the number of cells producing Fos in the PVN (133 Ϯ 23 vs. 1,336 Ϯ 43, respectively, P Ͻ 0.0001). Of the spinally projecting neurons in the PVN of heated rats (98 Ϯ 10), over 20% expressed Fos. Additionally, of the nitrergic neurons (NADPH-diaphorase positive) located in the parvocellular PVN (723 Ϯ 17), ϳ40% also expressed Fos (P Ͻ 0.0001 compared with controls). Finally, there was a significant increase in the number of spinally projecting neurons in the PVN that were nitrergic and expressed Fos after heat exposure (12%) compared with controls (0.1%) (P Ͻ 0.0001). These results suggest that spinally projecting and nitrergic neurons in the PVN may contribute to the central pathways activated by thermal stimulation. Fos immunohistochemistry; spinally projecting EXPOSURE TO A HOT TEMPERATURE challenge elicits responses mediated in part by the autonomic nervous system to promote heat loss and maintain body fluid homeostasis. Such responses include sweating, an increase in heart rate, increased respiration rate, skin vasodilation, and visceral vasoconstriction in humans; increased salivary secretion in rodents; and tail vasodilation in rats (25,27). The latter autonomic cardiovascular responses often involve changes in sympathetic nerve activity (SNA) and result in the redistribution of blood flow from the viscera to the skin. These changes are mediated by the central nervous system (CNS) (24,25,40,43,45,52,65).It has been well established that the CNS is essential in the regulation of body temperature. There are several brain regions that are likely to contribute to the CNS pathways that mediate the thermoregulatory responses. Studies using the marker of neuronal activation, Fos, or electrophysiological recordings have shown that several forebrain areas are activated after the elevation in body temperature (2, 5-7, 21, 28, 34, 38, 39, 42, 52, 53). These forebrain areas include the preoptic area, anterior hypothalamus, and the paraventricular nucleus (PVN) of the hypothalamus. The preoptic area and anterior hypothalamus are well known key thermoregulatory sites within the brain; however, a role of the PVN in thermoreg...

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“…The latter autonomic cardiovascular responses often involve changes in sympathetic nerve activity (SNA) and result in the redistribution of blood flow from the viscera to the skin. These changes are mediated by the central nervous system (CNS) (24,25,40,43,45,52,65).…”

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confidence: 99%

Activation of spinally projecting and nitrergic neurons in the PVN following heat exposure

Cham¹,

Klein²,

Owens³

et al. 2006

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The preoptic area in particular functions to monitor local temperature changes. Shivering is elicited when this area is cooled, and it is suppressed when it is warmed [3,4]. Our previous study has indicated that most efferent signals mediating these responses originate in warm-sensitive neurons [1, 2] and descend in the medial forebrain bundle [5].…”

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Hypothalamic Region Facilitating Shivering in Rats.

Tanaka

Tonouchi²,

Hosono

et al. 2001

JJP

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Shivering of skeletal muscle is the main effector response of homeothermic animals to the cold to maintain body temperature. The hypothalamus is of unquestionable importance in the control of shivering [1,2]. The preoptic area in particular functions to monitor local temperature changes. Shivering is elicited when this area is cooled, and it is suppressed when it is warmed [3,4]. Our previous study has indicated that most efferent signals mediating these responses originate in warm-sensitive neurons [1, 2] and descend in the medial forebrain bundle [5]. The posterior part of the hypothalamus also has long been considered to be important for the control of shivering and referred to as the "heat maintenance center" [6]. Lesions in the caudal hypothalamus abolished or impaired shivering, and shivering is invoked by electrical stimulation of this area [1,2]. More exactly designed lesion and stimulation experiments indicated that the dorsomedial region of the posterior hypothalamus is especially important for the production of shivering [7,8]. However, it is unclear whether it is the effects of electrical stimulation and lesioning on cell bodies or simply on axons originating in other brain regions that truly participate in the control of shivering, because both procedures influence cell bodies and passing fibers. The aim of the present study is to examine this question. We tested the effect on shivering activity of an injection of muscimol, a GABA A receptor agonist, into the posterior hypothalamus and adjacent regions in anesthetized rats. Because this chemical affects only the soma and dendrites, we reasoned that if muscimol influenced shivering, neurons that participate in the control of shivering should be found there. MethodsWe used 52 adult male Crj: Wistar rats (350-400 g, Charles River Japan, Yokohama, Japan) from a colony housed at 22°C with free access to food and water. The experiment was approved by the Animal Care Committee of Osaka University Medical School. After anesthesia with urethane (1.4 g/kg, I.P.), each rat was mounted in a stereotaxic apparatus according to the coordinate system of Paxinos and Watson [9]. A stainless steel guide tube (0.5 mm o.d.) was implanted into the hypothalamus 0.3-2.5 mm from the midline, 2.0-5.0 mm behind bregma, and the tip of this tube was 6.0-9.5 mm below the skull surface. In most cases two guide tubes were implanted, one on each Japanese Journal of Physiology Vol. 51, No. 5, 2001 625Japanese Journal of Physiology, 51, 625-629, 2001 Key words: shivering, posterior hypothalamus, dorsomedial hypothalamus. Abstract:Although the posterior part of the hypothalamus has long been considered important for thermoregulatory shivering, it is unknown whether the neurons there or the passing fibers are implicated in the response. Exposure of urethane-anesthetized rats to cold (15-21°C) elicits shivering. An injection of muscimol (0.5 mM), a GABA A receptor agonist, into the medial part of the hypothalamus, including the dorsomedial and posterior nuclei, suppressed the cold-...

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“…In the rat, as in all other species studied, the preoptic area contains neurones directly sensitive to changes in core temperature as well as neurones receiving inputs from peripheral thermoreceptors (Hellon & Taylor, 1982;Ishikawa et al 1984). Lesions in the preoptic area in the rat severely impair or abolish the ability to increase heat loss (Lipton, 1968(Lipton, , 1974Toth, 1973;Ishikawa et al 1984) and localised warming in the preoptic area of the rat at normal body temperatures activates the full range of heat loss behaviour (Lipton, 1973;Roberts & Martin, 1974;Ishikawa et al 1984;Nakayama et al 1986;Tanaka et al 1986;Kanosue et al 1990Kanosue et al , 1991. Neurones in the preoptic area of the rat also project to a wide range of midbrain and brainstem nuclei involved in autonomic functions, including those involved in the generation and control of breathing (Conrad & Pfaff, 1975, 1976Swanson, 1976;Veening et al 1982;Simerly & A. G. Boden, M. C. Harris and M. J. Parkes Exp.…”

Section: Hypothalamus and Thermoregulationmentioning

confidence: 99%

The preoptic area in the hypothalamus is the source of the additional respiratory drive at raised body temperature in anaesthetised rats

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Lateral distribution of hypothalamic signals controlling thermoregulatory vasomotor activity and shivering in rats

Cited by 27 publications

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Activation of spinally projecting and nitrergic neurons in the PVN following heat exposure

Activation of spinally projecting and nitrergic neurons in the PVN following heat exposure

Hypothalamic Region Facilitating Shivering in Rats.

The preoptic area in the hypothalamus is the source of the additional respiratory drive at raised body temperature in anaesthetised rats

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