title: Methamphetamine and core temperature in the rat: ambient temperature, dose, and the effect of a D2 receptor blocker.
abstract: BACKGROUND
  Methamphetamine (METH) induces hyperthermia in warm and hypothermia in cool environments. Our first goal was to further study the role of ambient temperature in METH's effect on core temperature in rats. Previously, these effects were primarily demonstrated in high doses; we extended this investigation to the low-dose range (1 mg/kg METH). Our second goal was to identify the role of the D2 receptor in METH's effects in cool ambient temperatures.
  
  
  METHODS
  Rats received METH (saline, 1, 5, and 10 mg/kg), raclopride (saline, 0.3, 0.6, and 1.2 mg/kg), or a combination (all doses of raclopride combined with 10 mg/kg METH). Treatments occurred in ambient temperatures of 18, 24, or 30 °C.
  
  
  CONCLUSIONS
  Consistent with prior research, 5 and 10 mg/kg METH caused hyperthermia or hypothermia in a dose- and ambient temperature-dependent manner (60 min after METH). In contrast, 1 mg/kg produced similar levels of hyperthermia at all ambient temperatures. These findings suggest that a threshold METH dose exists; below this dose, METH still changes core temperature, but CNS control over temperature regulation is left intact. In our experiments regarding D2 blockade, raclopride decreased METH-induced core temperature at 30 and 24 °C (60 min after METH), consistent with previous findings. We extended these findings by demonstrating that in a cool ambient temperature (18 °C), raclopride pretreatment also lowered the core temperature response to METH. Although the D2 receptor is known to mediate hypothermia, the combination of METH and D2 blockade suggests a complex mediation of the core temperature response, perhaps involving neurotransmitter interactions.
authors.affiliation: Psychology Department, University of Mississippi, 207 Peabody Building, University, MS 38677, USA ksabol@olemiss.edu
authors.forename: Karen E
authors.initials: KE
authors.lastname: Sabol
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Yancey
authors.forename: H Anton
authors.initials: HA
authors.lastname: Speaker
authors.forename: Scott L
authors.initials: SL
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D015259:Dopamine Agents / Q000008:administration & dosage / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D005334:Fever / Q000139:chemically induced*; D007035:Hypothermia / Q000139:chemically induced*; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage / Q000494:pharmacology*; D020891:Raclopride / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D013696:Temperature
chemical_list: D015259:Dopamine Agents; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D020891:Raclopride; D008694:Methamphetamine