Sex experience increases delta FosB in male and female hamsters, but facilitates sex behavior only in females.

Motivated behaviors share the common feature of activating the mesolimbic dopamine system. Repeated experience with motivated behaviors can cause long-lasting structural changes in the nucleus accumbens (NAc). The molecular mechanisms underlying this experience-dependent plasticity in the NAc have been well described following experience with drugs of abuse. In particular, the transcription factor Delta FosB (ΔFosB) is a key regulator of drug-related neuroplasticity. Fewer studies have examined the molecular mechanisms underlying experience-dependent plasticity in the NAc following naturally motivated behaviors, but previous research has demonstrated that sexual experience increases the accumulation of ΔFosB in the NAc of female hamsters and male rats. Sex behavior is unique among motivated behaviors in that the expression of the behavior varies drastically between males and females of the same species. Despite this, a quantitative comparison of ΔFosB following sex experience in males and females of the same species has never been conducted. We therefore used Western blotting to test the hypothesis that sex experience increases ΔFosB in both male and female Syrian hamsters following repeated sexual experience. We found that sex experience significantly increases ΔFosB protein in male and female Syrian hamsters. Further, ΔFosB protein levels did not differ between males and females following sex experience. Interestingly, repeated sex experience only led to increased copulatory efficiency in female hamsters; male copulatory efficiency did not improve with repeated experience. Together, these data demonstrate that ΔFosB is increased following sexual reward in both males and females but may be uncoupled from behavioral plasticity in males. (PsycINFO Database Record (c) 2019 APA, all rights reserved).