L-glutamate microinjection in the preoptic area increases brain and body temperature in freely moving rats.
The role of the preoptic area (POA) in thermoregulation is well documented. Microinjection of various neurotransmitters into the POA in rats has been shown to influence body temperature. Alhough there are reports showing changes in temperature on administration of L-glutamate into the POA, the role of this excitatory amino acid in thermoregulation has not been studied in unanaesthetized rats. In the present study, brain and body temperatures were recorded in freely moving adult male Wistar rats with K-type thermocouple implanted near the hypothalamus and temperature transmitter implanted inside the peritoneum. Recordings were performed 2 h preinjection and 4 h postinjection. L-glutamate (0.14 nM) microinjection into the POA induced long-lasting hyperthermia and reduced locomotor activity. The rats remained curled up and showed piloerection. L-glutamate-induced hyperthermia was attenuated by previous injection of the ionotropic L-glutamate receptor antagonist, kynurenate (0.11 nM). We propose that L-glutamate in the POA participates not only in heat production and conservation but also plays a role in interlinking sleep and thermoregulation.
aDepartment of Physiology, All India Institute of Medical Sciences, New Delhi bComprehensive Centre for Sleep Disorders, Sree Chitra Tirunal Institute for Medical Sciences & Technology, Kerala, India.
Trina
T
Sengupta
Ashok K
AK
Jaryal
Velayudhan M
VM
Kumar
Hruda N
HN
Mallick
D000818:Animals; D001831:Body Temperature / Q000187:drug effects*; D001833:Body Temperature Regulation / Q000187:drug effects*; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology*; D007736:Kynurenic Acid / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D011301:Preoptic Area / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid; D007736:Kynurenic Acid