The responses of preoptic thermosensitive neurons to non-thermal emotional stimuli in the monkey (original) (raw)
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Responsiveness of monkey preoptic thermosensitive neurons to non-thermal emotional stimuli
Brain Research Bulletin, 1986
Responsiveness of 143 preoptic neurons to changes in hypothalamic temperature and to non-thermal emotional stimuh were investigated while rewarding (foods) and aversive objects (hypertonic saline, a toy snake, an air puffer) were given. About 71% of thermosensitive neurons and 32% of thermally insensitive neurons changed the activity when emotional stimuli were shown to and/or tasted by the monkey. Such responses were modulated by satiety/hunger state and were dependent on the degree of perturbation of emotional state. About half of the neurons tested responded when the monkey opened the mouth and protruded the tongue or moved fingers in trying to obtain foods with strong motivation, but did not when the animal made such movements less readily or reluctantly with the progress of satiation. This response was most frequently found among warm-units. The results raise a possibility that preoptic thermosensitive neurons, besides their postulated thermoregulatory functions, might be involved in the response of coordination with thermal and non-thermal emotional behaviors controlled in the hypothalamus.
The dorsomedial hypothalamus: a new player in thermoregulation
AJP: Regulatory, Integrative and Comparative Physiology, 2006
Neurons in the dorsomedial hypothalamus (DMH) play key roles in physiological responses to exteroceptive (“emotional”) stress in rats, including tachycardia. Tachycardia evoked from the DMH or seen in experimental stress in rats is blocked by microinjection of the GABAA receptor agonist muscimol into the rostral raphe pallidus (rRP), an important thermoregulatory site in the brain stem, where disinhibition elicits sympathetically mediated activation of brown adipose tissue (BAT) and cutaneous vasoconstriction in the tail. Disinhibition of neurons in the DMH also elevates core temperature in conscious rats and sympathetic activity to least significant difference interscapular BAT (IBAT) and IBAT temperature in anesthetized preparations. The latter effects are blocked by microinjection of muscimol into the rRP, while microinjection of muscimol into either the rRP or DMH suppresses increases in sympathetic nerve activity to IBAT, IBAT temperature, and core body temperature elicited eit...
Neuroscience Letters, 2002
We recently reported that perfusion of tetrodotoxin (TTX) into the preoptic area and anterior hypothalamus (PO/AH), by using a microdialysis technique, induced an increase in body temperature (Tb) under normal and hot ambient temperatures (23 and 35 8C) in freely moving rats. However, the procedure had no effect on Tb under a cold ambient temperature (5 8C). The present study was designed to determine the mechanism(s) of increases in Tb after perfusion of TTX into the PO/AH, by measuring tail skin temperature (Ttail) as an index of heat loss, and heart rate (HR) and locomotor activity (Act) as indexes of heat production, under three ambient temperatures. Under normal ambient temperature (23 8C), perfusion of TTX induced significant hyperthermia with increased HR, Act and Ttail. In a hot environment (35 8C), perfusion of TTX induced a greater increase in Tb with increased HR but no change in Ttail and Act. In a cold environment (5 8C), perfusion of TTX had no effect on Tb with a slight increase in Act but no change in HR and Ttail. Our results suggest that the PO/AH may be involved in inhibition of heat production and excitation/inhibition of the tail vasomotor tone.
Skin or hypothalamus cooling: A behavioral choice by rats
Brain Research, 1984
Rats were chronically implanted with a hypothalamic thermode. After recovery the thermode was heated and the rats were exposed to 4 ambient temperatures (Ta) 20, 30, 35 and 40 °C. For each Ta they were subjected to 3 conditions: (1) they could press a bar which provided them with a cool wind; (2) they could press a bar which cooled the hypothalamic thermode; and (3) both bars were active and the rat could press either one. Skin, hypothalamic, and rectal temperatures were recorded at the same time. The results indicate that when rats had either only or by choice access to the lever that cooled their hypothalamus, they used it in such a way as to prevent their hypothalamus from overheating. A lower priority was given to the maintenance of skin temperature.
Neuropharmacology, 2002
Earlier microinjection studies showed that norepinephrine in the medial preoptico-anterior hypothalamic area (mPOAH) regulates body temperature and the action is mediated through α-1 adrenoceptors. This study was conducted to confirm if the thermosensitive neurons in the mPOAH of rats possess α-1 adrenoceptors. First, the thermosensitivity of mPOAH neurons was tested and then the effects of microiontophoretic application of prazosin, α1 adrenoceptor antagonist, on the firing rate of both the thermosensitive as well as the insensitive neurons were recorded. Prazosin significantly inhibited the firing rate of the thermosensitive neurons suggesting that most of the cold and warm sensitive neurons in the mPOAH possess α-1 adrenoceptors. These results at the single neuronal level confirm our earlier hypothesis that in the mPOAH, norepinephrine regulates body temperature by acting on α-1 adrenoceptors. The data also suggest that sensitivity of the mPOAH neurons to norepinephrine alter with changes in body temperature. The detailed physiological significance of the results with special reference to thermoregulation at the single neuronal level has been discussed.
Physiological and Behavioral Mechanisms of Thermoregulation in Mammals
Animals
This review analyzes the main anatomical structures and neural pathways that allow the generation of autonomous and behavioral mechanisms that regulate body heat in mammals. The study of the hypothalamic neuromodulation of thermoregulation offers broad areas of opportunity with practical applications that are currently being strengthened by the availability of efficacious tools like infrared thermography (IRT). These areas could include the following: understanding the effect of climate change on behavior and productivity; analyzing the effects of exercise on animals involved in sporting activities; identifying the microvascular changes that occur in response to fear, pleasure, pain, and other situations that induce stress in animals; and examining thermoregulating behaviors. This research could contribute substantially to understanding the drastic modification of environments that have severe consequences for animals, such as loss of appetite, low productivity, neonatal hypothermia...
Brain Research, 1993
Thermoregulation; Thermogenesis Normothermic (37°C), anesthetized Long Evans rats given unilateral electrical stimulation (0.5 ms monophasic pulses of 100-300 /zA at 50 Hz for 30 s) of the posterior hypothalamus (PH) had graded, sustained increases in EMG electrical activity of the gastronemius muscle (i.e. shivering). In a current-related manner, gastronemius muscle temperatures (T m) immediately increased following PH stimulation, surface temperatures (T t) did not change and colonic (core, T c) temperatures initially fell, then subsequently rose after the applied stimulus. A biphasic pressor response occurred after PH electrical stimulation associated with tachycardia. PH electrical stimulation (0.5 ms pulses at 50 Hz for 30 s of only 40/zA) induced shivering in anaesthetized, hypothermic Long Evans rats undergoing acute cold exposure. When these same hypothermic rats were cooled further to cause shivering, PH electrical stimulation (0.5 ms pulses at 50 Hz for 30 s of only 40/xA) induced further increases in the shivering response (]" EMG area of gastronemius muscle) from the shivering response before PH stimulation. Results indicate that electrical stimulation of the PH can evoke shivering in anesthetized normothermic rats. Stimulation of the PH with lower current intensity can induce or increase shivering of hypothermic rats previously exposed to the cold.
Brain Research, 1981
Key words: temperature regulation --serial lesion --hypothalamus --recovery of function Rats received 1-stage bilateral or sequential unilateral (serial) lesions of the posterior hypothalamus and were tested for the ability to regulate body temperature after a lengthy recovery period. The groups with lesion differed from the sham-operated groups in the cold, although not under ambient or warm conditions. The fact that the serial lesion group performed the same as the 1-stage lesion groups in the cold is significant because earlier tests on these same animals revealed much better recovery after serial lesions in swimming, and a partial serial lesion effect in open field performance.