Modulation of vigilance and behavioral activation by alpha-1 adrenoceptors in the rat.
This study investigated the role of alpha-1 adrenergic receptors in the modulation of attention and behavioral activity by assessing the effects of alpha-1 adrenergic receptor stimulation or blockade on the performance of rats in tasks involving vigilance (sustained attention) and selective attention [five-choice serial reaction time (5-CSRT)]. Pretesting subcutaneous administration of St-587 (a putative alpha-1 agonist) at 100 micrograms/kg, but not at 300 or 1000 micrograms/kg, significantly improved the choice accuracy of rats in the 5-CSRT task (monitoring of visual stimuli), whereas prazosin (a prototype alpha-1 antagonist) at 300 micrograms/kg administered subcutaneously slightly impaired choice accuracy of the rats in this task. Prazosin at 100 micrograms/kg blocked the ability of St-587 at 100 micrograms/kg to improve choice accuracy. Furthermore, St-587 at 100 micrograms/kg significantly increased the number of trials completed and reduced the probability of premature responses, whereas prazosin at 300 micrograms/kg decreased the number of trials completed and the latency of animals to make correct responses in the task. Prazosin at 100 micrograms/kg blocked the effect of St-587 at 100 micrograms/kg in increasing the number of trials completed. However, prazosin at 100 micrograms/kg did not abolish the effect of St-587 in reducing the probability of premature responses. Because the effect of St-587 at 100 micrograms/kg in improving choice accuracy is rather modest, it is possible that when the 100- and 300-microgram/kg doses of St-587 were administered in a counterbalanced order, this effect could have been overlooked due to day-to-day variation. Thus, the present results suggest that stimulation of alpha-1 adrenergic receptors can facilitate vigilance.
Puumala
T
T
A. I. Virtanen Institute, University of Kuopio, Finland.
Riekkinen
P
P
Sirviö
J
J
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001288:Attention / Q000187:drug effects / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018340:Receptors, Adrenergic, alpha-1; C030655:St 587; D003000:Clonidine; D011224:Prazosin