Brain Research, 422 (1987) 347-351 347 Elsevier BRE 22498 Short ~mu~ions Specific angi n II inthe rat ce ical iia Eero Castr6n, Masaki Kurihara, Jorge S. Gutkind and Juan M. Saavedra Unit on PreclinicalNeuropharmacology, Section on Clinical Pharmacology, Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20982 (U.S.A.) (Accepted 16 June 1987) Key words: Sympathetic ganglion; Neuropeptide receptor; Renin angiotensin system; Peripheral sympathetic system; Receptor autoradiography Angiotensin II binding sites were localized and quantified in rat stellate and superior cervical ganglia by quantitative autoradiogra- phy using 125I-Sarl-angiotensin II as a ligand. Both ganglia possess a single class of anglotensin II binding sites. High concentrations of binding sites were localized in the areas rich in principal ganglion cells. These binding sitesmight mediate the facilitatory action of an- giotensin II on the ganglionic transmission. Angiotensin II (Ang II) facilitates the activity of the sympathetic nervous system at several levels. Ang II increases the turnover of catecholamines in brain nuclei involved in the sympathetic system 16"23. facilitates adrenergic transmission in the sympathetic ganglia 6, stimulates catecholamine release in the adrenal medulla 15, and enhances release 11'27and bio- synthesis 2° of norepinephrine in the postganglionic sympathetic nerve terminals. In most cases this facilitation of the sympathetic transmission is mediated through a specific Ang II re- ceptor. Ang II possesses binding sites in central nu- clei connected to the regulation of sympathetic activi- ty, such as the hypothalamic paraventrieular nucleus, locus coeruleus and the nucleus of the solitary tract 21, and in the adrenal medulla s . So far there are, howev- er, no reports of the presence of specific angiotensin binding sites in the sympathetic ganglia. We have therefore used quantitative autoradio- graphy to localize Ang II binding sites in stetlate gan- glion (STG) and superior cervical ganglion (SCG) of the rat. This method has recently been used to loca- lize substance p14 and vasopressin 1° receptors in the sympathetic ganglia. The autoradiographic method allows us to perform kinetic receptor analysis in a sin- gle ganglion. Fourteen-week-old Sprague-Dawley rats were obtained from Zivic Miller (AUiston Park, PA). The animals were housed under constant temperature (20+1 °C) with lights on from 06.00 to 18.00 h and were given free access to food and water. The ani- mals were killed by decapitation between 09.00 and 12.00 h. The left STG and SCG were quickly re- moved and frozen by immersion m isopentane at -30 °C. Within 24 h, 16-/~m thick tissue sections were cut in a cryostat at -16 °C, thaw-mounted onto gela- tin-coated glass slides, and stored overnight under vacuum at 4 °C. Each experiment could be per- formed with a single ganglion and was repeated with ganglia obtained from 7 individual rats. Autoradiograms of Ang II binding sites were generated by incubating tissue sections for one hour at room temperature in 10 mM phosphate buffer (pH 7.4) containing 120 mM NaCI, 5 mM Na2EDTA, 0.1 mM bacitracin, and 0.2% bovine serum albumin with concentrations of 125I-Sar1-Ang II from 0.04 to 4.6 Correspondence: J.M. Saavedra, Unit on Preclinical Neuropharmacology, Section on Clinical Pharmacology, Laboratory of Clinical Science. National Institute of Mental Health, 9000 Roekvitle Pike, Building 10, Room 2D46. Bethesda. ME)20982, U.S.A.