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  • 1
    Electronic Resource
    Electronic Resource
    Effects of intracerebroventricular injection of clonidine on metabolic, respiratory, vasomotor and temperature responses in the rabbit (1981)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 315 (1981), S. 195-201 
    Details
    ISSN: 1432-1912
    Keywords: Clonidine ; 5-Hydroxytryptamine ; Hypothermia ; Metabolic rate ; Cutaneous vasodilatation ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The thermoregulatory outputs (including metabolic, respiratory and vasomotor activities) produced by an injection of clonidine or 5-hydroxytryptamine (5-HT) into the third cerebral ventricle of conscious rabbits were assessed at three different ambient temperatures (T a) of 2, 22 and 32°C. 2. When injected into the third cerebral ventricle, both clonidine and 5-HT produced a dose-dependent hypothermia in rabbits at both 2 and 22°C T a. The hypothermia was due to a decrease in metabolic heat production (M) at 2°C T a, while at 22°C T a the hypothermia was due to cutaneous vasodilatation. There were no changes in respiratory evaporative heat loss. 3. Furthermore, the clonidine-induced hypothermia was greatly reduced by pretreatment of the animals with either 5,6-dihydroxytryptamine (impairment of central 5-HT pathways) or yohimbine (alpha-adrenergic blocking agent), but not by 6-hydroxydopamine (impairment of central catecholamine pathways). 4. The results indicate that clonidine may act on the α-adrenergic receptors located on central 5-HT pathways to produce a hypothermic action by promoting a decrease in heat production or an increase in heat loss in the rabbit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499835
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  • 2
    Electronic Resource
    Electronic Resource
    Serotonergic mechanisms in the hypothalamus mediate thermoregulatory responses in rats (1983)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 322 (1983), S. 271-278 
    Details
    ISSN: 1432-1912
    Keywords: 5-Hydroxytryptamine ; Hypothalamus ; Thermoregulation ; Raphe nucleus ; Hypothermia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Either electrical stimulation of midbrain raphe nuclei or administration of 5-hydroxytryptamine (5-HT; serotonin) into the preoptic anterior hypothalamus caused hypothermia in conscious rats at ambient temperatures (T a) of both 8° C and 22°C. The hypothermia was due to decreased metabolic heat production at T a=8°C, while at T a=22°C the hypothermia was due to both decreased metabolism and increased heat loss (cutaneous vasodilatation). However, at T a=30°C, electrical stimulation of midbrain raphe or intrahypothalamic injection of 5-HT caused an insignificant change in the thermoregulatory responses. There was no changes in respiratory evaporative heat loss in response to these treatments at various T a's. 2. Direct administration of the serotonergic receptor antagonists such as cyproheptadine and methysergide into the preoptic anterior hypothalamus caused hyperthermia in conscious rats at T a's of 8°C, 22°C and 30°C. The hyperthermia was due to increased metabolism and cutaneous vasoconstriction. 3. The hypothermia induced by intrahypothalamic administration of 5-HT was antagonized by pretreatment with an intrahypothalamic dose of either cyproheptadine or methysergide in rats at T a=22°C. 4. Inhibition of 5-HT neuronal activity with administration of 5-HT into the midbrain raphe regions also caused hyperthermia, increased metabolism and cutaneous vasoconstriction in rats at T a's of 8°C, 22°C and 30°C. 5. These observations tend to suggest that the functional activity of serotonergic receptors in the preoptic anterior hypothalamus mediates thermoregulatory responses in the rat. Activation of serotonergic receptors in the hypothalamus decreases heat production and/or increases heat loss, while inhibition of serotonergic receptors in the hypothalamus increases heat production and/or decreases heat loss in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00508342
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Clonidine-induced hypothermia: Possible involvement of cholinergic and serotonergic mechanisms (1984)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 326 (1984), S. 124-128 
    Details
    ISSN: 1432-1912
    Keywords: Clonidine ; Hypothalamus ; 5-Hydroxytryptamine ; Acetylcholine ; Thermoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The thermoregulatory effects (including metabolic, vasomotor and respiratory activities) produced by an injection of clonidine (1–3 μg in 0.5 μl) into the preoptic anterior hypothalamus were assessed in conscious rats at ambient temperatures (T a) of 8, 22 and 30°C. 2. Intrahypothalamic administration of clonidine caused a dose-dependent fall in rectal temperature at T a 8°C and 22°C. The hypothermia in response to clonidine was due to decreased metabolic heat production and/or cutaneous vasodilation. There was no change in respiratory evaporative heat loss. 3. The clonidine-induced hypothermic response was attenuated by pretreatment of the rats with either 5,7-dihydroxytryptamine (10 μg, administered intrahypothalamicly, 14 days before clonidine injection), yohimbine (0.2 μg, administered intrahypothalamicly, 10 min before clonidine injection), cyproheptadine (1 μg, administered intrahypothalamicly, 10 min before clonidine injection), or atropine (0.1 μg, administered intrahypothalamicly, 10 min before clonidine injection). 4. The data indicate that clonidine may act on α-adrenoceptors located on a serotonin-acetylcholine pathway within the preoptic anterior hypothalamus to induce hypothermia by promoting a reduction in metabolic heat production and/or an enhancement in dry heat loss in rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00517308
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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