The Journal of Neuroscience, March 15, 2001, 21(6):2123-2130
Sexual Behavior Induction of c-Fos in the Nucleus
Accumbens and Amphetamine-Stimulated Locomotor Activity Are Sensitized
by Previous Sexual Experience in Female Syrian Hamsters
Katherine C.
Bradley1 and
Robert L.
Meisel2
1 Graduate Neuroscience Program, and
2 Department of Psychological Sciences, Purdue University,
West Lafayette, Indiana 47907-1364
Dopamine transmission in the nucleus accumbens can be activated by
drugs, stress, or motivated behaviors, and repeated exposure to these
stimuli can sensitize this dopamine response. The objectives of this
study were to determine whether female sexual behavior activates
nucleus accumbens neurons and whether past sexual experience cross-sensitizes neuronal responses in the nucleus accumbens to amphetamine. Using immunocytochemical labeling, c-Fos expression in
different subregions (shell vs core at the rostral, middle, and caudal
levels) of the nucleus accumbens was examined in female hamsters that
had varying amounts of sexual experience. Female hamsters, given either
6 weeks of sexual experience or remaining sexually naive, were tested
for sexual behavior by exposure to adult male hamsters. Previous sexual
experience increased c-Fos labeling in the rostral and caudal levels
but not in the middle levels of the nucleus accumbens. Testing for
sexual behavior increased labeling in the core, but not the shell, of
the nucleus accumbens. To validate that female sexual behavior can
sensitize neurons in the mesolimbic dopamine pathway, the locomotor
responses of sexually experienced and sexually naive females to an
amphetamine injection were then compared. Amphetamine increased general
locomotor activity in all females. However, sexually experienced
animals responded sooner to amphetamine than did sexually naive
animals. These data indicate that female sexual behavior can activate
neurons in the nucleus accumbens and that sexual experience can
cross-sensitize neuronal responses to amphetamine. In addition, these
results provide additional evidence for functional differences between the shell and core of the nucleus accumbens and across its
anteroposterior axis.
Key words:
female sexual behavior; nucleus accumbens; shell; core; c-Fos; sensitization; cross-sensitization; amphetamine
Copyright © 2001 Society for Neuroscience 0270-6474/01/2162123-08$05.00/0