Activation of alpha 2-adrenoceptors suppresses excessive wheel running in the semistarvation-induced hyperactive rat.
Male Wistar rats were housed in cages linked to running wheels and fed on a schedule designed to reduce their body weight by 20-30%. During this period of semistarvation, rats increased their daily running wheel activity (RWA) by up to 30 km/day. RWA could be kept at this level provided that body weight was kept constant. Different alpha-adrenergic agonists and antagonists were tested for their effects on RWA and it was found that RWA could be suppressed only by agonists that display high affinity for the alpha 2-receptor (clonidine and guanfacine). Neither antagonist had an effect on RWA. Clonidine's inhibiting effect on RWA was prevented by pretreatment with yohimbine, which also has high affinity for alpha 2-receptors. From these results, we conclude that semistarvation-induced hyperactivity can be blocked by alpha 2-agonists. In view of this result and those that were obtained in previous studies, a theoretical model for the development of semistarvation-induced hyperactivity will be presented.
Wilckens
T
T
Max-Planck-Institut for Psychiatry, München, Germany.
Schweiger
U
U
Pirke
K M
KM
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004435:Eating; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013217:Starvation / Q000523:psychology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D003000:Clonidine; D009638:Norepinephrine