A MICRODIALYSIS STUDY OF VENTRAL STRIATAL DOPAMINE DURING SEXUAL-BEHAVIOR IN FEMALE SYRIAN-HAMSTERS

Microdialysis was used to study the effects of exposure to a male hams ter on extracellular concentrations of dopamine, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindole acetic aci d (5-HIAA) in the ventral striatum of ovariectomized female Syrian ham sters pretreated with either estradiol and progesterone, or a similar regimen of oil injections. The hormone-treated females showed high lev els of lordosis throughout the hour of exposure to the male. In hormon e-treated females, there was a rapid elevation of dialysate dopamine w ithin the first 15 min of exposure to the male. Dialysate dopamine gra dually declined over the next 45 min, though remaining significantly a bove baseline during the entire period of exposure to the male. None o f the oil-treated females showed any indication of lordosis, and the a ddition of the male produced only a small increase in dopamine at 30 m in, after which dopamine returned to pre-male basal levels. DOPAC, HVA , and 5-HIAA were all elevated following introduction of the male for both groups of females. These results suggest that ovarian hormones mo dulate the responsivity of ventral striatal dopamine to incentive stim uli associated with mating behavior in females, although extracellular levels of dopamine in the ventral striatum do not seem to be directly coupled to the display of lordosis.