Journal of Neuroscience, Vol 14, 1555-1562, Copyright © 1994 by Society for Neuroscience
Evidence for a role of the shell of the nucleus accumbens in oral behavior of freely moving rats
EP Prinssen, W Balestra, FF Bemelmans and AR Cools
Department of Psycho- and Neuropharmacology, University of Nijmegen, The Netherlands.
Behavioral effects of intra-accumbens administration of the dopamine DAi
receptor agonist (3,4-dihydroxyphenylimino)-2-imidazoline (DPI) were
studied in freely moving rats. Three distinct areas were examined: core,
shell and "shore," namely, the border region of the core and shell. DPI (5
micrograms) administered into the shell, but not areas ventral to the
shell, increased chewing, tongue protrusion, sniffing, and grooming; it
also induced abnormal oral behavior, namely, large- amplitude chewing. A
similar dose of DPI administered into the core did not affect any
(peri-)oral behavior, except sniffing. Because of methodological
constraints the receptor specificity of the DPI effects was studied in rats
with cannulas directed at the shore. DPI (5.0-10.0 micrograms) administered
into the shore increased oral behavior dose dependently; however, the
dose-effect curve varied per distinct type of oral behavior. The dopamine
DAi receptor antagonist ergometrine attenuated the effect of DPI on tremor,
chewing, and sniffing frequencies. Taken together, the data show that the
effects of DPI were DAi receptor specific. It is concluded that stimulation
of dopamine DAi receptors in the shell modulates and induces (peri-)oral
behaviors in freely moving rats.