Kippin Tod E, van der Kooy Derek
Neurobiology Research Group, Department of Anatomy & Cell Biology, University of Toronto, 1 King's College Circle, Toronto, Ontario, M5S 1A8, Canada.
Eur J Neurosci. 2003 Nov;18(9):2581-91. doi: 10.1046/j.1460-9568.2003.02918.x.
The tegmental pedunculopontine nucleus (TPP) of the brainstem mediates food reward in food-sated animals and opiate reward in drug-naive animals. In the present study, we examine the effect of excitotoxic lesions of the TPP on sexual behaviour in naive and experienced male rats. Male, Long-Evans rats received either 0.25 micro L injections of NMDA (4.2 micro g/side) or vehicle (shams) into the TPP. In sexually naive males, complete bilateral TPP lesions decreased all measure of copulation (i.e. mounts, intromissions and ejaculations), prevented acquisition of conditioned sexual excitement, decreased approach preference for a receptive female over a non-receptive one, and decreased non-contact erections; unilateral or bilateral posterior-sparing TPP lesions did not affect any of these measures. Conversely, in sexually experienced males, lesions not only failed to disrupt copulation, but also increased conditioned sexual excitement, decreased post-ejaculatory interval and blocked the effect of prolonged copulation on conditioned sexual excitement. Following differential pairing of distinctive environments with and without copulation, sham males with sexual experience displayed a significant preference for the environment paired with copulation, whereas the lesion males with sexual experience displayed a significant aversion for the environment paired with copulation. These findings indicate that the TPP is critical for the acquisition of copulation in naive males and mediates the rewarding consequences of copulation in experienced males. Together these findings demonstrate that the TPP mediates sexual reward, but that sexual experience is not sufficient to produce a deprivation state.
脑干的被盖脚桥核（TPP）在进食已饱动物中介导食物奖赏，在未接触过药物的动物中介导阿片类药物奖赏。在本研究中，我们研究了TPP的兴奋性毒性损伤对未接触过性行为和有性经验的雄性大鼠性行为的影响。雄性Long-Evans大鼠在TPP中接受0.25微升NMDA（4.2微克/侧）注射或注射溶媒（假手术组）。在未接触过性行为的雄性大鼠中，完全双侧TPP损伤降低了所有交配指标（即爬跨、插入和射精），阻止了条件性性兴奋的获得，降低了对可接受雌性而非不可接受雌性的接近偏好，并减少了非接触性勃起；单侧或双侧保留后部的TPP损伤对这些指标均无影响。相反，在有性经验的雄性大鼠中，损伤不仅未能破坏交配，反而增加了条件性性兴奋，缩短了射精后间隔，并阻断了长时间交配对条件性性兴奋的影响。在将独特环境与有无交配进行差异配对后，有性经验的假手术组雄性大鼠对与交配配对的环境表现出显著偏好，而有性经验的损伤组雄性大鼠对与交配配对的环境表现出显著厌恶。这些发现表明，TPP对未接触过性行为的雄性大鼠获得交配至关重要，并介导了有性经验的雄性大鼠交配的奖赏后果。这些发现共同表明，TPP介导性奖赏，但性经验不足以产生剥夺状态。
