1. ¹Neurophysiology and Experimental Neuroethology Laboratory, Ribeirão Preto School of Medicine, University of São Paulo, Avenida Bandeirantes, Ribeirão Preto, São Paulo, Brazil
2. ²Neuroendocrinology Laboratory, Department of Physiology, Ribeirão Preto School of Medicine, University of São Paulo, Avenida Bandeirantes, Ribeirão Preto, São Paulo, Brazil
3. ³Department of Neurology, Psychiatry and Medical Psychology, Ribeirão Preto School of Medicine, University of São Paulo, Avenida Bandeirantes, Ribeirão Preto, São Paulo, Brazil

Correspondence: Dr N Garcia-Cairasco, Neurophysiology and Experimental Neuroethology Laboratory, Ribeirão Preto School of Medicine, University of São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto, São Paulo 14049-900, Brazil. E-mail: ngcairas@fmrp.usp.br

⁴These authors contributed equally to this work.

⁵Current address: Catholic University of Brasília, DF, Brazil.

Received 5 August 2005; Revised 29 March 2007; Accepted 5 April 2007; Published online 15 May 2007.

Abstract

Oxytocin (OT) is a neurosecretory nonapeptide synthesized in hypothalamic cells that project to the neurohypophysis as well as to widely distributed sites in the central nervous system. Central OT microinjections induce a variety of cognitive, sexual, reproductive, grooming and affiliative behaviors in animals. Obsessive-compulsive disorder (OCD) includes a range of cognitive and behavioral symptoms that bear some relationship with OT. Here, we study the neuroanatomical and cellular substrates of the hypergrooming induced by administration of OT in the central nucleus of amygdala (CeA). In this context, this hypergrooming is considered as a model of compulsive behavior. Our data suggest a link between the CeA and the hypothalamic grooming area (HGA). The HGA includes parts of the paraventricular nucleus and the dorsal hypothalamic area. Our data on colocalization of OT (immunohistochemistry for peptide), OT receptor (binding assay) and its retrogradely labeled cells after Fluoro-Gold injection in the CeA suggest that CeA and connections are important substrates of the circuit underlying this OT-dependent compulsive behavioral pattern.