Release of prostaglandin E2 from brain of cat: II. In vivo studies on the effects of adrenergic, cholinergic and dopaminergic agonists and antagonists.
This study examined the effect of several neurotransmitters, receptor agonists and antagonists on the release of prostaglandin E2 (PGE2) from brain. Levels of PGE2 were measured in consecutive 30-min samples, collected from ventriculocisternal perfusions (100 microliters/min) in chloralose-urethanized cats, before, during and after the addition of carbachol, norepinephrine (NE) and dopamine (DA). Samples were submitted to acid organic extraction and radioimmunoassay (RIA) with a specific antibody. Displacement curves of ligand binding with control and stimulated samples were parallel to those observed with PGE2. The addition of carbachol (10(-4) M) to the perfusate resulted in a significant increase in the levels of PGE2 from 600 +/- 259 pg PGE2/min during the control period up to 1306 +/- 429 pg PGE2/min during the perfusion (P less than 0.02). Though NE (10(-3) M) and isoproterenol (10(-3) M, beta) were without effect, methoxamine (10(-3) M, alpha 1), but not ST-91 (an alpha 2-agonist), produced an increase in secretion of PGE2. This increase was blocked by phentolamine (10(-3) M). The addition of DA (10(-4) M) produced a fall from control levels of 642 +/- 185 pg PGE2/min to 290 +/- 101 pg PGE2/min (P less than 0.02). These results suggest that the central activation of selected populations of receptors will alter basal levels of PGE2 in the extracellular space.
Navarro
E
E
Section of Neurosurgical Research, Mayo Clinic, Rochester, Minnesota 55905.
Romero
S D
SD
Yaksh
T L
TL
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002415:Cats; D015232:Dinoprostone / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000187:drug effects*; D011954:Receptors, Dopamine / Q000187:drug effects*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011950:Receptors, Cholinergic; D011954:Receptors, Dopamine; D015232:Dinoprostone