Effects of cold stress on some 5-HT1A, 5-HT1C and 5-HT2 receptor-mediated responses.
The purpose of the present study was to analyze the influence of stress (24-h cold exposure) on presynaptic 5-HT1A receptors, and on postsynaptic 5-HT1A, 5-HT1C and 5-HT2 receptors. Cold exposure for 24 h affected neither pargyline-induced decreases in 5-hydroxyindoleacetic acid (5-HIAA) levels in midbrain and rest of brain, nor plasma glucose and corticosterone levels. Treatment with the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.5-1 mg/kg), 3-5 h after the end of cold exposure triggered less intense flat body posture and forepaw treading in cold-exposed rats than in controls. On the other hand, 15- and 30-min plasma glucose responses to 8-OH-DPAT (0.25-0.5 mg/kg, 3-5 h after cold) or to the alpha 2-adrenoceptor agonist, clonidine (0.025 mg/kg), were not affected by cold, while the 15-min, but not the 30 min, plasma corticosterone response to 8-OH-DPAT was slightly amplified in cold-exposed rats. Cold exposure affected neither the inhibitory effect of 8-OH-DPAT (0.25-0.5 mg/kg, 3-5 h after cold) on midbrain 5-HIAA levels, nor the hypothermic effect of 8-OH-DPAT (0.5-1 mg/kg, 3-5 h after cold). Lastly, the hypoactivity elicited by the 5-HT1C receptor agonist, m-chlorophenyl-piperazine (1.5-3 mg/kg, 3-5 h after cold), or head shakes elicited by the 5-HT2 receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (1-2 mg/kg, 3-5 h after cold), were of similar intensities in control and in cold-exposed rats.
Zamfir
O
O
Laboratoire de Pharmacologie, CNRS, CHU Necker, Paris, France.
Broqua
P
P
Baudrie
V
V
Chaouloff
F
F
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001786:Blood Glucose / Q000378:metabolism; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D003080:Cold Temperature; D003345:Corticosterone / Q000097:blood; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D001786:Blood Glucose; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D003345:Corticosterone