Previous evidence has shown that histamine (HA) increases prolactin (PRL) release in adult male and female rats. This response is depending on the age of the animals and some differences were appreciated between male and female rats. In addition, at 20 days of age the PRL response was greater than earlier ages. The purpose of the present communication was to study further this response and to define the type of HA receptor that may be involved in the mediation of this PRL response.

Induction of prolactin release by H1- or H2-histamine agonists in maturing male and female rats.

and clinical studies in patients with cimetidineassociated mental confusion, Lancet 27, 177-181 (1979). [7] W. LORENZ, A. DOENICKE, B. SCHONING, J. MAMORSKI, O. WEBER, E. HINTERLANG, B. SCHWARZ and E. NEUGEBAUER, e I + H2-receptor antagonists for premeditation in anaesthestia and surgery: A critical view based on randomized clinical trials with haemaceel and various antiallergenic drugs, Agents and Actions 10, 114-124 (1980). [81 I. PAAKKARI, A simple method for the verification of a successful cannulation of the rat cerebral ventricles, Experientia 36, 887-888 (1980). [9] I. PAAKKAm, Computerized recording of ventilation, cardiovascular parameters and body temperature in anaesthetised rats, J. Pharmacol. Meth. 6, 97-107 (1981). [10] M.E. PARSONS, The antagonism of histamine H 2receptors in vivo with particular reference to the actions of eimetidine. In Cimetidine, pp. 13-20 (Eds W.L. BURLAND and M.A. SIMKINS). Excerpta Medica, Amsterdam 1977. [11] W.A. MAHON and M. KOLTON, Hypotension after intravenous cimetidine, Lancet 1,828 (1978). [12] J. COHEN, A.P. WEETMAN, H.J. DARGIE and D.M. KmKLER, Life-threatening arrhythmias and intravenous cimetidine, Br. Med. J. 2, 768 (1979). [13] H. KARPPANEN, I. PAAKKARI and P. PAAKKARI, Further evidence for central histamine H2-receptor involvement in the hypotensive effect of clonidine in the rat, Eur. J. Pharmacol. 42, 299-302 (1977). [14] H. KARPPANEN, I. PAAKKARI and P. PAAKKARI, Studies on the nature of cerebral receptors mediating the hypotensive effect of clonidine in rats. In Histamine Receptors, pp. 255-269 (Ed. T.O. YELLIN). Spectrum Publications, New York 1979. [15] P.E. HICKS, Central cardiovascular actions of histamine in rats: Involvement of histamine H2-receptors, Clin. Exp. Hypertension 1, 251-265 (1978). [16] I. PAAKKARI, P. PAAKKARI and H. KARPPANEN, Central cardiovascular effects of the selective histamine H2-receptor agonist dimaprit in the rat, Acta Pharmacol. Toxicol. 41, suppl. 4, 67 (1977). [17] I. PAAKKARI, Cardiovascular and respiratory effects induced by central histamine H r and H2-receptor stimulation in anaesthetized rats, First Soviet-Finnish symposium in neurotransmitters and the mechanism of action of neurotropic and cardiovascular drugs, Abstracts, 85 (1979).

Z. Huszti

Papers

Recent status of histamine in the brain.