Arendash G W, Gorski R A
Pharmacol Biochem Behav. 1983 Aug;19(2):351-7. doi: 10.1016/0091-3057(83)90064-3.
The effects of biphasic electrical stimulation of the mesencephalic median (MRN) and dorsal raphe (DRN) nuclei, as well as the adjacent periaqueductal gray (PAG), on lordotic behavior were investigated in ovariectomized rats primed with three daily injections of estradiol benzoate (2 micrograms). Animals were tested between 4-8 hours after a progesterone (0.5 mg) injection on day four which normally facilitates high levels of receptivity during this period. Although stimulation of the MRN had no significant effect on lordosis, DRN activation at 100 Hz (0.5 msec pulse duration) or 10 Hz (2 msec pulse duration) caused a marked and immediate suppression (53% and 56%, respectively) in receptivity. This suppression does not appear to be due to activation of serotoninergic neurons originating in the DRN since pretreatment with an inhibitor of serotonin synthesis (parachlorophenylalamine, 320 mg/kg) essentially did not modify the suppression, thus providing no evidence in support of an inhibitory role for serotonin in lordotic behavior. Activation within the PAG adjacent to the DRN at 10 Hz (0.5 or 2 msec pulse duration) produced an immediate, dramatic decrease (81% and 80%, respectively) in receptivity. The suppressions induced by DRN and PAG stimulation appear most likely to be due to activation of a descending pathway inhibitory to the lordosis reflex at medullary or spinal cord levels.
研究了对接受每日三次苯甲酸雌二醇（2微克）注射预处理的去卵巢大鼠，中脑正中核（MRN）、中缝背核（DRN）以及相邻的导水管周围灰质（PAG）的双相电刺激对脊柱前凸行为的影响。在第四天注射孕酮（0.5毫克）后4至8小时对动物进行测试，在此期间孕酮通常会促进高水平的接受性。虽然刺激MRN对脊柱前凸没有显著影响，但以100赫兹（脉冲持续时间0.5毫秒）或10赫兹（脉冲持续时间2毫秒）激活DRN会导致接受性显著且立即受到抑制（分别为53%和56%）。这种抑制似乎不是由于源自DRN的血清素能神经元的激活，因为用血清素合成抑制剂（对氯苯丙氨酸，320毫克/千克）预处理基本不会改变这种抑制，因此没有证据支持血清素在脊柱前凸行为中起抑制作用。在与DRN相邻的PAG内以10赫兹（脉冲持续时间0.5或2毫秒）激活会使接受性立即显著下降（分别为81%和80%）。DRN和PAG刺激所诱导的抑制最有可能是由于在延髓或脊髓水平激活了一条对脊柱前凸反射起抑制作用的下行通路。
