van Hest A, van Haaren F, van de Poll N E
Behavioral Neuroendocrinology Unit, Netherlands Institute for Brain Research, Amsterdam.
Behav Brain Res. 1988 Mar;27(3):215-21. doi: 10.1016/0166-4328(88)90118-0.
Male rats both eat more and weigh more than females. Differences in food intake and body weight result, at least partly, from differences in gonadal hormone secretions. The present experiments were designed to investigate whether sex differences in food motivation might contribute to the behavioral differences observed when food-deprived male and female rats are exposed to appetitively motivated operant learning tasks. Male and female Wistar rats were exposed to different progressive ratio schedules of reinforcement which have been shown to generate reliable indices of 'motivational' conditions. In progressive ratio schedules, subjects are required to make a systematically increasing number of responses for each successive reinforcer, until the requirement becomes so large that the subjects stop responding. Expt. Ia was designed to investigate whether or not food-deprived males would be more motivated than food-deprived females to obtain food. Expt. Ib investigated whether gonadectomy might differentially affect food motivation of male and female rats exposed to a progressive ratio schedule of reinforcement. Motivational differences between males and females were not observed. Males and females obtained an equal number of reinforcers, while differences in the total number of responses and response rate were not observed. Gonadectomy did not affect the total number of responses in the final completed ratio. The results of the present experiments do therefore not support the hypothesis that sex differences in food motivation might underlie sex differences in behavior when food-deprived male and female rats are exposed to operant schedules of positive reinforcement.
雄性大鼠比雌性大鼠吃得更多且体重更重。食物摄入量和体重的差异至少部分源于性腺激素分泌的差异。本实验旨在研究当剥夺食物的雄性和雌性大鼠接受以食欲为动机的操作性学习任务时，食物动机方面的性别差异是否可能导致所观察到的行为差异。将雄性和雌性Wistar大鼠暴露于不同的渐进比率强化程序中，这些程序已被证明能产生可靠的“动机”条件指标。在渐进比率程序中，要求受试者为每个连续的强化物做出系统增加数量的反应，直到要求变得如此之高以至于受试者停止反应。实验Ia旨在研究剥夺食物的雄性大鼠是否比剥夺食物的雌性大鼠更有动力获取食物。实验Ib研究了去势是否会对暴露于渐进比率强化程序的雄性和雌性大鼠的食物动机产生不同影响。未观察到雄性和雌性之间的动机差异。雄性和雌性获得的强化物数量相等，同时在总反应次数和反应率方面未观察到差异。去势并未影响最终完成比率中的总反应次数。因此，本实验的结果不支持这样的假设，即当剥夺食物的雄性和雌性大鼠接受正强化的操作性程序时，食物动机的性别差异可能是行为性别差异的基础。
