Locomotor hyperactivity induced by blockade of prefrontal cortical alpha2-adrenoceptors in monkeys.
BACKGROUND
Stimulation of alpha(2)-adrenergic receptors (alpha(2)-ARs) in the prefrontal cortex (PFC) has a beneficial effect on working memory and attentional regulation in monkeys. alpha(2)-adrenergic agonists like clonidine and guanfacine have been used experimentally and clinically for the treatment of attention deficit and hyperactivity disorder (ADHD). However, it is unknown if alpha(2)-ARs in the PFC are involved in the neural mechanisms underlying regulation of locomotor activity.


METHODS
The alpha(2)-adrenergic antagonist yohimbine was infused bilaterally and chronically into the dorsolateral PFC (dlPFC) in two monkeys, using mini-osmotic pumps. Spontaneous locomotor activity was measured continuously before, during and after drug administration, using an activity monitor.


RESULTS
The monkeys exhibited a dramatic increase in motoric activity during infusion of yohimbine into the dlPFC. Similar treatment with saline was without effect. Thus, the locomotor hyperactivity was due to blockade of alpha(2)-ARs, not because of nonspecific factors such as cortical damage by drug administration.


CONCLUSIONS
The present study suggests that alpha(2)-ARs in the dlPFC are involved in inhibitory control of locomotor activity.
Ma
Chao-Lin
CL
Institute of Neurobiology, Fudan University, Shanghai, The People's Republic of China.
Arnsten
Amy F T
AF
Li
Bao-Ming
BM
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage; D000818:Animals; D004334:Drug Administration Schedule; D005260:Female; D006948:Hyperkinesis / Q000139:chemically induced / Q000503:physiopathology*; D008253:Macaca mulatta; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D017397:Prefrontal Cortex / Q000187:drug effects*; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D015016:Yohimbine / Q000008:administration & dosage
D058669:Adrenergic alpha-2 Receptor Antagonists; D000317:Adrenergic alpha-Antagonists; D018341:Receptors, Adrenergic, alpha-2; D015016:Yohimbine