The effect of two different types of stress on locus coeruleus alpha-2 receptor binding.
The central noradrenergic neurons of the locus coeruleus (LC) are important in regulating an animal's response to a stressor. Changes in alpha-2 autoreceptors on LC neurons during stress could alter the functional state of the LC. We investigated the changes in binding of LC alpha-2 receptors immediately following 1 h and 4 h of two stressors: novelty + cold and prone restraint. We measured the specific binding of the alpha-2 receptor antagonist [3H]idazoxan in the LC of rats using in vitro autoradiography. Specific binding was increased after 1 h of novelty + cold exposure but decreased after 4 h, and after both 1 and 4 h of prone restraint. The increase after 1 h of stress may be due to the ability of LC neurons to regulate their own activity because this would produce a dampening of the high LC activity produced by the stressor. However, extended time and/or intensity of a stressor may overwhelm this initial response and produce an agonist-induced decrease in receptor binding.
Weiss
G K
GK
University of New Mexico School of Medicine, Albuquerque 87131.
Ratner
A
A
Voltura
A
A
Savage
D
D
Lucero
K
K
Castillo
N
N
D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000818:Animals; D003080:Cold Temperature / Q000009:adverse effects; D004146:Dioxanes / Q000378:metabolism; D019329:Idazoxan; D008125:Locus Coeruleus / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D013312:Stress, Physiological / Q000209:etiology / Q000378:metabolism*
D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D018340:Receptors, Adrenergic, alpha-1; D019329:Idazoxan