System Emotional Science, University of Toyama, Toyama 930-0194, Japan.
J Neurosci. 2012 Feb 1;32(5):1672-86. doi: 10.1523/JNEUROSCI.5140-11.2012.
Previous behavioral studies have indicated that the nucleus accumbens (NAc) shell of a male rat is involved in its sexual behavior; however, no previous studies have investigated neuronal activities in the male rat NAc shell during sexual behavior. To investigate this issue, we recorded single unit activities in the NAc shell of male rats during sexual behavior. Of 123 NAc shell neurons studied, 53, 47, and 40 neurons exhibited significantly changed firing rates at various times during intromission, genital auto-grooming, and sniffing of females, respectively. The two types of NAc shell neurons [putative fast spiking interneurons (pFSIs) and medium spiny neurons (pMSNs)] responded differently during sexual behavior. First, more pFSIs than pMSNs exhibited inhibitory responses to thrusting with intromission and genital grooming, while pFSIs and pMSNs responded similarly to sniffing of females. Second, both pFSIs and pMSNs responded differently to thrusting with and without intromission. Furthermore, NAc shell neuronal activity was significantly different across the different phases of sexual behavior, and the number of NAc shell neurons with delta oscillation, which is related to behavioral inhibition, and high gamma oscillation, which is related to reward perception, increased after ejaculation. Together, our results suggest that the NAc shell is deeply involved in sexual behavior, and changes in NAc shell neuronal activity are related to performance of sexual behavior, encoding cues or contexts related to sexual behavior, reward-related processing, and the inhibition of sexual behavior after ejaculation.
先前的行为研究表明，雄性大鼠的伏隔核（NAc）壳参与其性行为；然而，先前的研究尚未调查雄性大鼠 NAc 壳在性行为期间的神经元活动。为了研究这个问题，我们记录了雄性大鼠性行为期间 NAc 壳中单神经元的活动。在研究的 123 个 NAc 壳神经元中，分别有 53、47 和 40 个神经元在插入、生殖器自梳理和嗅探雌性时的不同时间表现出显著变化的放电率。两种类型的 NAc 壳神经元[推测的快速放电中间神经元（pFSIs）和中等棘突神经元（pMSNs）]在性行为期间表现出不同的反应。首先，与插入和生殖器梳理时的插入相比，更多的 pFSIs 表现出抑制反应，而 pFSIs 和 pMSNs 对雌性的嗅探反应相似。其次，pFSIs 和 pMSNs 对带有和不带插入的插入反应不同。此外，NAc 壳神经元活动在性行为的不同阶段有显著差异，与行为抑制相关的 δ 振荡和与奖励感知相关的高γ振荡的 NAc 壳神经元数量在射精后增加。总的来说，我们的结果表明 NAc 壳深深参与性行为，NAc 壳神经元活动的变化与性行为的表现、与性行为相关的线索或背景的编码、与奖励相关的处理以及射精后性行为的抑制有关。
