Lorenzo A, Carrer H F
Instituto de Investigacion Medica Mercedes y Martin Ferreyra, Cordoba, Argentina.
Physiol Behav. 1988;42(5):417-22. doi: 10.1016/0031-9384(88)90170-9.
Using a combination of injection cannula and recording electrode, the effect of 1 microliter of 3 mM verapamil upon the multiunit responses evoked in the peripeduncular nucleus (PPN) by electric stimuli applied to the pudendal nerves in urethane anesthetized proestrous female rats was studied in 9 experiments. It was observed that in 6 cases responses were suppressed after the injection and in 2 other cases there was a marked decrease, whereas no change was observed in 1 case. Similar injections of vehicle (saline) produced no change (7 rats) or small and short lasting depression of evoked activity (4 rats). Similar injections of verapamil applied to a region of the mesencephalic reticular formation caudal to the PPN, presumably containing fibers that carry evoked activity towards the PPN, had no effect on evoked multiunit activity in the PPN. Injection of 2% Xylocaine in the same site in the same animal eliminated the evoked responses. These experiments support our hypothesis that verapamil suppressed evoked responses in the PPN blocking Ca++-dependent release of neurotransmitter at local synapsis, without interfering with fiber conduction of neural activity. Based on this assumption we used identical injections to test the hypothesis that activation of neurons in the PPN is necessary for the performance of lordotic behavior in ovariectomized rats primed with estradiol benzoate. Guide cannulae aimed at the PPN were implanted in castrated females which were then primed with enough estradiol benzoate to induce sexual receptivity.(ABSTRACT TRUNCATED AT 250 WORDS)
在9个实验中，研究人员使用注射套管和记录电极相结合的方法，观察了1微升3毫摩尔维拉帕米对在氨基甲酸乙酯麻醉的动情前期雌性大鼠中，通过刺激阴部神经在脚周核（PPN）诱发的多单位反应的影响。结果发现，6例在注射后反应受到抑制，2例明显减弱，1例无变化。类似地，注射溶媒（生理盐水）后，7只大鼠无变化，4只大鼠诱发活动出现短暂轻微抑制。向PPN尾侧的中脑网状结构区域注射维拉帕米（该区域可能含有向PPN传导诱发活动的纤维），对PPN中的诱发多单位活动没有影响。在同一只动物的相同部位注射2%的利多卡因可消除诱发反应。这些实验支持了我们的假设，即维拉帕米通过阻断局部突触处依赖钙离子的神经递质释放来抑制PPN中的诱发反应，而不干扰神经活动的纤维传导。基于这一假设，我们采用相同的注射方法来检验以下假设：对于用苯甲酸雌二醇预处理的去卵巢大鼠，PPN中神经元的激活对于其出现脊柱前凸行为是必要的。将导向PPN的引导套管植入去势雌性大鼠体内，然后用足够剂量的苯甲酸雌二醇进行预处理以诱导性接受能力。（摘要截短于250字）
