To explore if there are sex differences in basal or DAMGO-stimulated [35S]GTPγS binding in A/A and G/G mice, the data of males and females were analyzed separately. There were no sex differences in basal [35S]GTPγS binding in A/A or G/G mice in any of the brain regions. As shown in Fig. 3, males G/G mice showed significantly higher net DAMGO-stimulated [35S]GTPγS binding than female G/G mice in the cingulate cortex, CPu, NAc core, thalamus and amygdala. In contrast, there are no sex differences in A/A mice. In addition, in the NAc core, female A/A mice displayed significantly higher DAMGO-stimulated [35S]GTPγS binding than female G/G mice (Fig. 4).
