Vasopressin in neuronal cultures from neonatal rat brain.

This study was performed to characterize and quantify vasopressin in neuron-enriched primary cultures of whole brains from 1-day-old rats and to compare such cultures between spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Vasopressin was extracted from cells and evaluated by radioimmunoassay and high-pressure liquid chromatography. Radioimmunoassay of high-pressure liquid chromatography fractions from cell extracts showed that the major peak of immunoreactivity comigrated with synthetic vasopressin. Cell vasopressin content increased in a graded manner when one to six dishes (plated 8 x 10(6) cells/dish) were pooled (8.7 +/- 0.5 to 67.7 +/- 8.2 pg/dish). When the number of plated cells per dish was increased (2 to 16 x 10(6) cells), there was also a graded rise in dish vasopressin content (3.4 +/- 0.4 to 15.3 +/- 3.9 pg). Treatment of cultures with 100 aM to 1 nM of angiotensin II for 5 minutes caused a dose-dependent decrease in cell vasopressin content. Furthermore, the decrease in cell vasopressin content of cultures treated with 1 nM angiotensin II (12.6 +/- 0.8 to 7.0 +/- 1.0 pg/10(6) cells, p less than 0.05) corresponded with the increase in medium vasopressin concentration (3.8 +/- 0.5 to 7.5 +/- 2.3 pg/ml) and this vasopressin-releasing effect of angiotensin II was blocked by [Sar1, Thr8]angiotensin II. Treatment of cultures with potassium chloride (56 mM) and acetylcholine chloride (5.5 microM) also resulted in significant decreases in cell vasopressin content.(ABSTRACT TRUNCATED AT 250 WORDS)