The Enhancement of Chlorpromazine‐induced Hypothermia by Lesions in the Anterior Hypothalamus

Abstract

I Administration of chlorpromazine (Cpz), either systemically or centrally, to unanaesthetized rats at an environmental temperature of 230C caused dose-dependent hypothermia. 2 In order to achieve equivalent hypothermia, intraventricular administration required a total dose of 20 1tg Cpz and intraperitoneal administration a dose of 9.7 mg/kg body weight. Accordingly, the doseratio between intraventricular and intraperitoneal administration was 1 to 110. Cpz apparently exerts its hypothermic effect by acting directly on central nervous structures rather than through peripheral sites. 3 Cpz-induced hypothermia was potentiated by preoptic anterior hypothalamic (POAH) lesions but not by lesions of the ventromedial nucleus (VMN) of the hypothalamus. It was found that Cpz induced hypothermia most readily in rats with large POAH lesions (-10.40C), less so in rats with spinal lesions (-5.5°C) at least with control rats (-2.9°C).

Effects of Brain Serotonin Alterations on Hypothermia Produced by Chlorpromazine in Rats

“…There fore, they concluded that the hypothermia induced by systemically administered CPZ is mediated by sites outside the central nervous system. On the other hand, for an equivalent hypothermia, the effectiveness of CPZ de creased from intracerebroventricular to the intracarotid and finally to the intraperitoneal route of administration in the rat (8). Hence, these investigators insisted that CPZ exerts its hypothermic effects mainly through the central nervous system rather than through peripheral sites.…”

“…Direct injection of the drug (CPZ) either into the preoptic anterior hypothalamic area or into the ventricular system has been shown to cause dose-related hypothermia in monkeys (7), in hamsters (22) and in rats (8).…”

Hypothermie unter Olanzapin

“…Dazu zäh-len im Falle von Unterkühlung autonome Reaktionen wie Veränderungen der Vasomotorik (wie periphere Vasokonstriktion und arteriovenöses Shunting an Fingern und Zehen) sowie das Auslösen peripher-muskulären Zitterns zur Wärme-erzeugung [33]. Ratten mit Läsionen der präoptischen hypothalamischen Region zeigten hypotherme Reaktionen nach Applikation von Antipsychotika [5,6]. Aber auch der dorsomediale Hypothalamus (DMH) scheint in die Thermoregulation involviert zu sein [9].…”

Thyrotropin-Releasing Hormone-Induced Hyperglycemia: Possible Involvement of Cholinergic Receptors in the Lateral Hypothalamus

“…The cervi cal vertebrae was exposed and completely transected with a spa tula at the seventh cervical spinal cord [2], In some animals, a bila teral vagotomy was made in the neck region, whereas a bilateral adrenalectomy was made at the abdominal region. Sham opera tions were performed on some animals by making an incision in the neck region.…”