Hypothalamic thermoregulatory

Injection studies have shown that nickel can decrease body temperature (Gordon 1989 Gordon et al. 1989 Hopfer and Sunderman 1988 Watanabe et al. 1990). Because nickel also disturbs the circadian rhythm of temperature regulation, this decrease is thought to result from an effect on the central nervous system. It has been speculated that nickel may mimic the effect of calcium on the hypothalamic thermoregulatory center resulting in hypothermia (Hopfer and Sunderman 1988). 

Antipyretic action Salicylates lower the elevated body temperature. Hypothalamic thermoregulatory centre acts as a thermostat of the body which maintains the balance between heat production and heat loss. Salicylates reset the hypothalamic thermostat which is disturbed during fever. They do not affect the heat production but they increase the heat loss by causing vasodilatation and sweating. The antipyretic action of salicylates is probably due to the inhibition of PG synthesis. 

Barbiturates do not raise the pain threshold and have no analgesic property. In anesthetic doses, they depress all areas of the CNS, including the hypothalamic thermoregulatory system, respiratory center, and vasomotor centers, as well as the polysynaptic pathways in the spinal column. In addition, some, such as phenobarbital, but not all, are anticonvulsants. In toxic doses, barbiturates cause oliguria. 

Ni may mimic or substitute for essential elements (i.e., for Ca in the hypothalamic thermoregulatory center resulting in hypothermia for Mg and Ca in enzyme processes). 

Fever is common a mechanism is the release of interleukin-1 by leucocytes into the circulation which acts on receptors in the hypothalamic thermoregulatory centre, releasing prostaglandin Ej. 

These agents decrease the synthesis of prostaglandin E2 (PGE2), which acts to reset the hypothalamic thermoregulatory mechanisms at increased temperature. 

Thermoregulation. PG raise the set point of hypothalamic (preoptic) thermoregulatory neurons body temperature increases (fever). 

Fever. Prostaglandins appear to be pyretogenic that is, they help produce the elevated body temperature during fever.55 Although the details are somewhat unclear, prostaglandins produced in hypothalamic blood vessels may promote fever by altering the thermoregulatory set-point within the hypothalamus so... 

Hypothermia associated with hypothalamic and thermoregulatory dysfunction has been reported in a patient with Prader-Willi syndrome taking risperidone and olanzapine (222). Hypothermia in response to these drugs is said to result from 5-HT2 receptor blockade, and it is recommended that patients with hypothalamic dysfunction should be carefully monitored if risperidone or olanzapine are used. 

Hori, T., 1980, The capsaicin-desensitized rat behavioral thermoregulation and thermosensitivity of hypothalamic neurons, in Thermoregulatory Mechanisms and Their Therapeutic Implications, (B. Cox, P. Lomax, A. S. Milton, and F. Schonbaum, eds.), pp. 214-216, Karger, Basel. 

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