Differential plasma catecholamine and neuropeptide Y responses to acute stress in rats.
Neuropeptide Y (NPY) is a vasoconstrictor present in the sympatho-adrenomedullary system and may be co-released with norepinephrine (NE) and epinephrine (EPI) during sympathetic activation. We studied plasma NPY-immunoreactivity (-ir, radioimmunoassay) and catecholamine (radioenzymatic) responses during two acute stress paradigms that differ in character, intensity, and duration. The intermittent stress of footshock (0.75 and 1.5 mA, 0.5 sec duration, at 5-sec intervals, for 5 min) evoked intensity-dependent immediate increments in plasma NE and EPI, and a delayed NPY-ir response (+0.6 +/- 0.1 pmol/ml). Prolonged (60 min) immobilization caused greater increases in plasma NE and EPI levels and no changes in plasma NPY-ir until the end of the stress session (+0.3 +/- 0.1 pmol/ml). Plasma NPY-ir responses correlated with those of NE but not with EPI suggesting a sympathetic origin for the release of the peptide. Relatively greater NPY-ir responses to footshock than to immobilization may be consistent with a preferential release of the peptide by a bursting but not continuous mode of sympathetic activation. However, it may also be due to a differential activation of the sympathetic nerves and adrenal medulla by these two stress situations.
Zukowska-Grojec
Z
Z
Department of Physiology and Biophysics, Georgetown University, Washington, D.C. 20007.
Konarska
M
M
McCarty
R
R
D000818:Animals; D004597:Electroshock; D004837:Epinephrine / Q000097:blood*; D008297:Male; D009478:Neuropeptide Y / Q000097:blood*; D009638:Norepinephrine / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D012149:Restraint, Physical; D013312:Stress, Physiological / Q000097:blood* / Q000209:etiology
D009478:Neuropeptide Y; D009638:Norepinephrine; D004837:Epinephrine