Cranial puncture, a simple procedure requiring no preparatory surgery: validation by observation of drinking and salt appetite evoked by intracerebroventricular renin

A non-surgical procedure, "cranical puncture" (CP), for pulse intracerebroventricular (p.i.c.v.) injection of solutions in adult rats is described. The injections are made by pushing a needle through the scalp and skull while the rats are under brief carbon dioxide narcosis from which behavioral recovery is rapid. The method was validated by comparing the effects of renin injected either by CP or through conventional chronic ventricular cannulas. Renin injections by either procedure evoked copious drinking of water (224 ± 23 ml/24 h) and 3% NaCl (44 ± 9.1 ml/24 h) at smaller doses than previously reported. Cranial puncture is proposed as a simple method of i.c.v. injection for behavioral experimentation in rats, and its advantages are discussed.