Sex differences in striatal dopamine: in vivo microdialysis and behavioral studies

Abstract

Experiments were conducted to examine sex differences in striatal dopamine function using in vivo microdialysis in freely moving rats. We report here a sex difference in basal extracellular striatal dopamine determined by quantitative microdialysis (the no net flux method) when castrated and ovariectomized rats were compared. There was no sex difference in dopamine uptake into synaptosomes. This indicates that the sex difference in extracellular dopamine is most likely due to sex differences in dopamine release, synthesis, and/or metabolism. Within 30 min after a single injection (s.c.) of either estradiol benzoate (2.0 micrograms/100 g) or 17 beta-estradiol (1.5 micrograms/100 g) the amphetamine-stimulated release of dopamine was enhanced in the striatum of ovariectomized rats, but there was no effect in castrated male rats. The enhanced amphetamine-induced striatal dopamine release in ovariectomized rats was associated with an enhanced frequency of stereotyped head and limb movements and an increased peak in extra 1/4 turns. There were also sex differences in stereotyped behavior and extra 1/4 turns whether or not animals received estrogen treatment. Thus, there are sex differences in striatal extracellular dopamine and in the effect of estrogen on the striatal dopamine neurochemical and behavioral responses to amphetamine.

Effects of Smoking Abstinence on Visuospatial Working Memory Function in Schizophrenia

“…Our data in control smokers suggests that there may be gender-related differences in the effects of cigarette smoking on this aspect of cognitive function. This observation could relate to estrogen's potentiation of central DA function (Castner et al 1993;Markowska 1999). …”

Topographical Assessment of Ethological and Dopamine Receptor Agonist-Induced Behavioral Phenotype in Mutants with Congenic DARPP-32 ‘Knockout’

“…However, DAergic function and responsivity to agonists have been shown to vary over the estrus cycle, with gender-dependent levels of basal extracellular DA in the striatum and nucleus accumbens thought to reflect variations in synthesis, release, and metabolism (Becker and Cha, 1989;Castner et al, 1993;Diaz-Veliz et al, 1994;Becker, 1999;Sell et al, 2000). Thus, the presence of DARPP-32 in the normal striatum and nucleus accumbens (Hemmings et al, 1992) might indicate a basis for hormonally modulated variations in DAergic transduction in DARPP-32 mutants over the estrus cycle.…”

Sex Differences and Hormonal Influences on Acquisition of Cocaine Self-Administration in Rats

“…Estradiol has been shown to influence DA activity in brain regions that are important in mediating drug reward. Estradiol increases AMPH-stimulated DA release from the striatum (Castner et al, 1993;Becker and Rudick, 1999) and attenuates DA reuptake in the nucleus accumbens (Thompson, 1999). Although estradiol affects DA-mediated behaviors and DA neurotransmission in females, it does not appear to do so in males.…”

“…Although estradiol affects DA-mediated behaviors and DA neurotransmission in females, it does not appear to do so in males. For example, exogenous estradiol administration to castrated males did not enhance AMPH-stimulated stereotyped head or forelimb movements, or AMPH-stimulated DA in dialysate from the striatum, although it enhanced both measures in OVX females (Castner et al, 1993). Since mesotelencephalic DA systems are thought to mediate reward (Wise and Bozarth, 1987), it is likely that the ability of estradiol to facilitate DA activity is related to estradiol's facilitation of cocaine selfadministration behavior in females.…”