Thurston C L, Randich A
Department of Biomedical Sciences, University of South Alabama, Mobile, AL 36688 USA Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294 USA.
Pain. 1995 Jul;62(1):19-38. doi: 10.1016/0304-3959(94)00223-2.
The relationships between mean arterial blood pressure (MAP) and the activity of putative pain modulatory neurons of the rostroventral medulla (ON and OFF cells) were determined in intact and cardiopulmonary deafferented rats. A total of 173 neurons were recorded from 97 rats as follows: 32 ON cells and 25 OFF cells from 39 intact rats; 32 ON cells and 20 OFF cells from 24 rats with bilateral sino-aortic deafferentation (SAD); 12 ON cells and 20 OFF cells from 19 rats with bilateral cervical vagotomy (CVAG); and 20 ON cells and 12 OFF cells from 15 rats with both SAD and CVAG. ON and OFF cells showed spontaneous fluctuations in activity such that ON cell activity was negatively correlated with MAP whereas OFF cell activity was positively correlated with MAP under conditions of no applied stimuli. These correlations were present in both intact and cardiopulmonary deafferented rats. Further, experimentally induced increases in MAP decreased ON cell activity and increased OFF cell activity in intact rats, but not in rats with SAD, CVAG, or the combination of SAD and CVAG. Experimentally induced decreases in MAP decreased OFF cell activity in intact rats and rats with CVAG, but not in rats with SAD or the combination of SAD and CVAG. These findings indicate that ON and OFF cells are modulated by baroreceptor activity, but baroreceptor input is not necessary for the spontaneous fluctuations in ON and OFF cell activity. Electrical stimulation of vagal afferents (VAS) inhibited 60% of the OFF cells studied, excited 4%, and produced biphasic effects consisting of excitation at low intensities and inhibition at greater intensities in 28% of all OFF cells. In general, VAS excited the majority of the ON cells studied, although there were significant differences between effects in intact and cardiopulmonary deafferented rats. Greater intensities of VAS that inhibited OFF cells and excited ON cells also inhibited the tail flick. Thus, inhibition of OFF cells and excitation of ON cells was correlated with antinociception. The effects of intravenous (i.v.) administration of 1.0 mg/kg morphine on neuronal activity did not differ between intact and cardiopulmonary deafferented rats.(ABSTRACT TRUNCATED AT 400 WORDS)
在完整大鼠和心肺去传入大鼠中，确定了平均动脉血压（MAP）与延髓头端腹内侧假定的疼痛调节神经元（开细胞和关细胞）活动之间的关系。从97只大鼠中总共记录了173个神经元，具体如下：从39只完整大鼠中记录了32个开细胞和25个关细胞；从24只双侧窦主动脉去传入（SAD）大鼠中记录了32个开细胞和20个关细胞；从19只双侧颈迷走神经切断（CVAG）大鼠中记录了12个开细胞和20个关细胞；从15只同时进行SAD和CVAG手术的大鼠中记录了20个开细胞和12个关细胞。开细胞和关细胞的活动呈现出自发性波动，在无外加刺激的情况下，开细胞活动与MAP呈负相关，而关细胞活动与MAP呈正相关。完整大鼠和心肺去传入大鼠均存在这些相关性。此外，实验性诱导的MAP升高会降低完整大鼠开细胞的活动并增加关细胞的活动，但在SAD大鼠、CVAG大鼠或SAD与CVAG联合手术的大鼠中则不会。实验性诱导的MAP降低会降低完整大鼠和CVAG大鼠关细胞的活动，但在SAD大鼠或SAD与CVAG联合手术的大鼠中则不会。这些发现表明，开细胞和关细胞受压力感受器活动的调节，但压力感受器输入对于开细胞和关细胞活动的自发性波动并非必需。迷走神经传入电刺激（VAS）抑制了60%的被研究关细胞，兴奋了4%，并在所有关细胞的28%中产生了低强度兴奋和高强度抑制的双相效应。一般来说，VAS兴奋了大多数被研究的开细胞，尽管完整大鼠和心肺去传入大鼠的效应存在显著差异。抑制关细胞并兴奋开细胞的更高强度VAS也抑制了甩尾反应。因此，抑制关细胞和兴奋开细胞与抗伤害感受相关。静脉注射（i.v.）1.0mg/kg吗啡对神经元活动的影响在完整大鼠和心肺去传入大鼠之间没有差异。（摘要截断于400字）
