Determinants of hypothalamic neuronal thermosensitivity in ground squirrels and rats

Ja, Boulant; Bignall, KE

doi:10.1152/ajplegacy.1973.225.2.306

Cited by 31 publications

(11 citation statements)

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“…Even in the 24 day old rats, slowly firing warm-units were frequently found among adult-like rapidly firing warm-units. In the rats of 21-24 IS PRY 294 T. HORI AND K. SHINOHA RA days of age, 55-6 % (15 of 27) of warm-units had firing rates at 38 TC of less than 5 impulses/sec, while in the adult rat and guinea-pig the percentage of such slowly firing units was only 10O3 % (4 of 39) (Boulant & Bignall, 1973).…”

Section: Resultsmentioning

confidence: 98%

“…It has previously been pointed out that warm-units in the preoptic and anterior hypothalamic areas are more readily found among those units having higher spontaneous firing rates (Boulant & Bignall, 1973). In the new-born rats, too, 30 2 % (39 of 129) of units having firing rates at 38 0C greater than 5 impulses/sec were warm-responsive, while the percentage of warm-units in the units having firing rates at 38 00 of 5 impulses/sec or less was only 15 5 % (79 of 511).…”

Section: Resultsmentioning

confidence: 99%

“…(Hyvarinen, 1966;Deza & Eidelberg, 1967;Huttenlocher, 1967;Henderson et al 1971), although the spontaneous firing rates of lateral hypothalamic neurones in 8-21 day old rats have already reached characteristically low adult levels (Almli, McMullen & Golden, 1976). According to Boulant & Bignall (1973) The events which determine the increase in firing rates of preoptic and anterior hypothalamic neurones during the postnatal period are not known. The evidence presently available suggests at least two factors.…”

Section: Resultsmentioning

confidence: 99%

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Hypothalamic thermo‐responsive neurones in the new‐born rat.

Hori¹,

Shinohara²

1979

The Journal of Physiology

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SUMMARY1. Single unit activities were recorded from the neurones in the preoptic area and anterior hypothalamus of developing new-born rats (aged 1-24 days old) during thermal stimulation of the brain. During the first 2 weeks of life, about 80 % of these neurones had low spontaneous firing rates between 0.1 and 5 impulses/sec at 38 0C hypothalamic temperature (Thyp).2. Out of 640 units studied, 118 units increased the firing rate upon elevation of ThyP (warm-units) and fourteen showed the opposite type of response to temperature changes (cold-units),. Warm-units were founcli the rats of all the age span studied and cold-units were recorded in the rats more than 8 days old.3. Thermal coefficients of warm-units and cold-units varied between +0i11 and +2-47 and between -0.10 and -0*49 impulses/sec. 0C, respectively. Number of warm-units with higher rates of firing and greater thermal coefficients, comparable to those of warm-units in the adult, gradually increased with growth. The thermal responsiveness of warm-units, when expressed by Q10, are already high even in the immediate neonatal period. Their Q10 values were in the range between 2 and 38X5 (mean 6.4).4. Units responding to extrahypothalamic temperatures were only found in the rats more than 14 days old.5. All the six warm-units tested increased the firing rates following subcutaneous injections of capsaicin, while the majority of thermo-unresponsive units were not affected by this drug.6. It is suggested that thermo-responsive neurones in the preoptic area and anterior hypothalamus in the new-born rat have attained some degree of electrophysiological maturity, despite their slowly firing characteristics.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Hypothalamic thermo‐responsive neurones in the new‐born rat.

Hori¹,

Shinohara²

1979

The Journal of Physiology

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“…For two decades it has been known that neurons of the hypothalamic preoptic area serve as major organizers in thermoregulation [3, 4, 5, 6, 7, 8, 9, 10]. The preoptic area receives thermal signals from the periphery through primary sensory afferents, which are relayed by neurons in medullary and pontine thermosensitive areas [11, 12, 13].…”

Section: Introductionmentioning

confidence: 99%

Fine Topography of Brain Areas Activated by Cold Stress

Baffi

Palkovits²

2000

Neuroendocrinology

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Neuronal activity in response to acute cold exposure was mapped in the central nervous system of adult rats using Fos immunostaining. A single, 3-hour exposure to cold elicited strong Fos-like immunoreactivity in the medial preoptic nucleus that is known as the thermoregulatory center of the brain. By this technique, pontine and medullary thermosensitive areas have been first localized and outlined anatomically. The medullary thermosensitive neurons occupy well-demarcated areas immediately ventral and dorsal to the spinal trigeminal nucleus, termed peritrigeminal and paratrigeminal nuclei, respectively. Cold-sensitive neurons were present in the dorsal part of the pontine reticular formation. Topographically, this area corresponds to the ‘pontine thermoregulatory area’, named on the basis of neurophysiological observations. In addition, thermosensitive neurons were found in the rostral thalamus and zona incerta. Several cell groups that showed strong Fos-like immunoreactivity in our previous pain-related stress experiments were also activated by cold exposure. The midline thalamic, hypothalamic dorsomedial, supramamillary and lateral parabrachial nuclei were targets of cold stress-induced noxious stimuli. Fos-positive neurons established specific topographical patterns in the paraventricular, arcuate, central amygdaloid nuclei, and the nucleus of the solitary tract. The possible involvement of central noradrenergic neurons in stress response to acute cold exposure was investigated by double immunostaining for tyrosine hydroxylase (TH) and Fos. None of the tyrosine hydroxylase positive neurons in the brain stem established Fos-like immunoreactivity, suggesting that the central noradrenergic system may have a minor, if any, role in cold-induced stress responses. Based on the topographical distribution of Fos-activated neurons, this study suggests that in addition to the hypothalamo-pituitary-adrenal axis, some other stress effector systems may play an important role in the maintenance of homeostasis during cold stress.

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“…Vertical lines two conventions according to which neurons are characterized as warm-sensitive (TC>0.6 or >0.8) the average, a consistent interrelationship seems to exist between the temperature dependence of the A current, its rate of inactivation at normothermia, the temperature coefficient of the neuron, and its spontaneous activity at normal T c . Since the latter property is, in turn, assumed to be related inversely to cell size (Boulant and Bignall 1973), attributing a thermosensory function to a neuron with a high temperature dependence of A-current inactivation would, in the end, reflect a morphological criterion. Drawing an analogy to peripheral cold and warm receptors does not seem to be revealing, since their cell somata, though small, resemble in size the somata of many non-thermal afferents.…”

Section: Mechanisms Of Temperature Transductionmentioning

confidence: 99%

The enigma of deep-body thermosensory specificity

Simón¹

2000

International Journal of Biometeorology

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Information provided by the analysis of peripheral cold and warm receptors may be considered a useful guide for assessing the specificity of thermal information originating in deep-body tissues. A wealth of data concerning the location of deep-body thermosensors and their neuronal correlates and modes of transduction permits the following theses to be proposed. 1. Unlike the peripheral warm and cold receptors, deep-body thermosensors are only in part represented by afferent fibers, mostly warm sensitive ones that are not characterized in detail, as the source of thermal information outside the central nervous system (CNS). The more important thermal information generated in the CNS originates mainly from warm-sensitive neurons but contributions of cold-sensitive neurons are not definitely excluded. 2. Unlike the peripheral thermoreceptors, monomodality with respect to natural physical stimuli does not seem to be an essential property of deep-body thermosensors. By contrast, multimodality may underlie at least some of the multitude of interactions between thermoregulatory and other homeostatic control systems. 3. Temperature transduction seems to utilize molecular mechanisms that are also found in neurons that lack any thermosensory functions, and so the transduction mechanisms identified in warm-sensitive CNS neurons do not seem to be specific per se. 4. The observation of a multitude of temperature/response characteristics for thermosensitive CNS neurons has been helpful for categorizing these neurons, but there is no clear information that any one might be particularly relevant. 5. Originating from the peripheral cold and warm receptors two separate but interacting cold- and warm-signal pathways ascend multisynaptically to the hypothalamus as the highest level of thermoregulatory control, and to some extent go further to the sensory cortex. The signal contributed by a deep-body thermosensitive neuron, irrespective of its location, attains specificity by being fed properly into one of the two ascending thermosensory pathways.

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Determinants of hypothalamic neuronal thermosensitivity in ground squirrels and rats

Cited by 31 publications

References 0 publications

Hypothalamic thermo‐responsive neurones in the new‐born rat.

Hypothalamic thermo‐responsive neurones in the new‐born rat.

Fine Topography of Brain Areas Activated by Cold Stress

The enigma of deep-body thermosensory specificity

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