Comparison of membrane electrical properties of somatic nociceptive and non-nociceptive neurons of the anterior cingulate gyrus in cats / 生理学报

ABSTRACT

Using intracellular potential recording technique in vivo, a series of hyperpolarizing and depolarizing currents at different intensities with a 50-ms duration were injected to somatic nociceptive neurons (SNNs) and somatic non-nociceptive neurons (SNNNs) in the anterior cingulate gyrus (ACG) of cats. The membrane electrical responses of the neurons were recorded, and the membrane electrical parameters of the neurons were calculated for comparative study on membrane electrical properties of SNNs and SNNNs of the ACG. A total of 188 ACG neurons from 57 cats were recorded. Among the 188 neurons, 172 (91.5%) and 16 (8.5%) were SNNs and SNNNs, respectively. The I-V curves of SNNs and SNNNs in the ACG were "S" shapes. When the absolute value of injected current intensity was less than or equal to 1 nA (≤ 1 nA), the I and V of I-V curves of both SNNs and SNNNs were linearly correlated (rSNNs = 0.99, rSNNNs = 0.99). When the absolute value of injected current intensity was more than 1 nA, both SNNs and SNNNs showed a certain inward or outward rectification behavior. Compared with SNNNs, SNNs had stronger rectification and lower adaptability (P < 0.01). With the increase of injected current intensity, the changes of frequency of discharges of SNNs were higher than those of SNNNs. In addition, the membrane resistance (Rm), the membrane capacity (Cm) and the time constant (τ) of SNNs were larger than those of SNNNs (P < 0.05 or P < 0.01). The differences in the membrane electrical properties between SNNs and SNNNs in the ACG suggested the disparity in neuronal cell size and cell membrane structure between them. The results of this study provided the experimental basis for deeply elucidating the mechanisms of somatic nociceptive sensation and characteristics on the membrane electrical aspects of ACG neurons.