Neuroscience Letters, 110 (1990) 303-308 303 Elsevier Scientific Publishers Ireland Ltd. NSL 06718 Increased dopamine release in the nucleus accumbens of copulating male rats as evidenced by in vivo voltammetry Manuel Mas 1, Jose Luis Gonzalez-Mora 1, Alain Louilot 2, Carlos So161 and Teresa Guadalupe I IDepartamento de Fisiologia, Universidadde La Laguna, Tenerife, (Spain) and 2Laboratoirede Psychobiologie des Comportements Adaptatifs, INSERM U. 259, Universit~de Bordeaux II, Bordeaux (France) (Received 20 June 1989; Revised version received 3 October 1989; Accepted 25 October 1989) Key words: Differential normal pulse voltammetry; Numerical analysis; Dopamine; Dihydroxyphenyl- acetic acid; Nucleus accumbens; Male sexual behavior This report describes the changes in extracellular levels of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) detected in the nucleus accumbens of male rats engaged in copulatory activity. They were monitored by using differential normal pulse voltammetry (DNPV) with electrochemically pretreated car- bon fiber microelectrodes and numerical analysis of the catechol signal. The copulatory pattern displayed during the voltammetric recordings was similar to those recorded prior to surgery. Copulating animals showed a conspicuous increase in the DA and DOPAC electrochemical signals up to, respectively, 170% and 150~; of baseline levels. This response was much attenuated when the experimental animals were exposed to either non-receptive castrated females or intact males. These data are consistent with the permissive role currently ascribed to the dopaminergic innervation of the n. accumbens in the selection and the initiation of behavioral adaptive sequences. The monoamine neurotransmitters have long been ascribed important regulatory roles in sexual behavior (for reviews see refs. 3, 19). For many years this concept was based exclusively on the demonstration that reproductive behavior is often influenced by drugs which alter the release or activity of biogenic amines. Recent stu- dies, however, have also documented changes in the levels of endogenous mono- amines and their metabolites in homogenates of different brain regions of animals sacrificed shortly after displaying sexual behavior [1, 10, 14]. As a further step we have explored whether such neurochemical phenomena could be assessed by contin- uous monitoring with in vivo voltammetry. This report describes the changes in extracellular levels of dopamine (DA) and its main metabolite dihydroxyphenylacetic Correspondence." M. Mas, Departamento de Fisiologia, Facultad de Medicina, 38320 Tenerife, Spain. 0304-3940/90/$ 03.50 © 1990 Elsevier Scientific Publishers Ireland Ltd.