Role of alpha(1)-adrenoceptors of the locus coeruleus in self-stimulation of the medial forebrain bundle.
The present experiments were undertaken to clarify the role of central alpha(1)-adrenoceptors in reward processes. Rats, trained to self-stimulate via electrodes in the medial forebrain bundle of the lateral hypothalamus, were administered alpha(1)-selective drugs near the locus coeruleus (LC), a site of a dense concentration of alpha(1)-receptors. Effects on reward potency were assessed from shifts in rate-frequency curves while effects on motor response capacity were judged from changes in the maximal rates of responding. It was found that local blockade of LC alpha(1)-receptors with terazosin produced a significant dose-dependent and site-dependent rightward shift of 0.08 log units and a significant decrease of 16.3% in the maximum response rate. Both effects were completely reversed by coadministration of the alpha(1)-agonist, phenylephrine and were not attributable to terazosin's weak action at alpha(2)-adrenoceptors. It is concluded that LC alpha(1)-adrenoceptors are involved both in reward/motivational processes and operant response elaboration which are postulated to work together to facilitate goal attainment.
Lin
Yan
Y
Department of Psychiatry, New York University School of Medicine, New York University Medical Center, New York, NY 10016, USA.
de Vaca
Soledad Cabeza
SC
Carr
Kenneth D
KD
Stone
Eric A
EA
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000379:methods; D008125:Locus Coeruleus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008474:Medial Forebrain Bundle / Q000502:physiology* / Q000528:radiation effects; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D012646:Self Administration / Q000379:methods
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; C041226:Terazosin; D011224:Prazosin