Integrative mechanisms for protopathic sensation including pain and g ravitropism

研究了秀丽隐杆线虫伤害和重力反应的神经元机制。野生型秀丽花分别受到有毒或高重力刺激。有害刺激包括机械刺激（von Frey型装置）、化学刺激、热刺激、pH刺激和渗透刺激。重力刺激为1.2 ~ 2.0 g的高重力刺激。主要结果如下：(1)逃避反射的机械刺激阈值低于人的疼痛感觉阈值。(2)产生疼痛的物质如缓激肽、组胺、5-羟色胺等对秀丽隐杆线虫的回避反射不起作用。(3)低pH和低渗透刺激对卷绕反射的诱发效果较好。接下来，我们研究了有害和重力刺激之间的相互作用。为此，比较重力刺激前后的痛觉阈值。采用离心装置施加高重力。30分钟。对于力学阈值，重力刺激后更高。重力模拟的阈值变化程度呈剂量-响应模式，例如，2G刺激比1.2 G刺激对von frey诱导的逃逸反应更有效。引起伤害性反应的化学阈值即使在重力刺激后也没有改变。2G刺激增强低渗诱导的逃逸行为。目前的结果表明，原感可能在中枢神经系统中整合。伤害感和重力感对动物物种的保存都是至关重要的。

Neuronal mechanisms of nociceptive and gravitational responses were investigated in c. elegans. Wild type c.eleganse was stimulated by noxious or high gravity stimulation. Noxious stimulations were maechanical (von Frey type apparatus), chemical, heat, pH and osmomic ones. Gravity stimulation was high- gravity of 1.2-2.0G. Main results were as follows: (1)Threshold values of mechanical stimulation for avoidance reflex showing escape from the stimulus site were lower than that evoked pain sensation in man. A typical behavior of avoidance reflex is peristalsis or coiling motion (2)Pain producing substances, such as Bradykinin, Histamine, 5-HT were not effective on the avoidance reflex in C. elegans. (3)Low pH and low osmomic stimulation were quite effective for evoking coiling reflex.Next, we investigated interaction between noxious and gravitational stimuli. For this purpose, nociceptive threshold before and after gravitational stimulation were compared. Centrifugal apparatus were used to apply high gravity. For 30 min. For mechanical threshold, it was higher after gravitational stimulation. Degree of threshold changes by gravitational simulation was dose-response fashon For example, 2G was more effective than 1.2 G stimulation on the von Frey-induced escape response. Chemical threshold to evoke nociceptive response were not changed even after gravitational stimulation. 2G stimulation enhanced low osmimic-induced escape behavior. The present results suggest that prtopathic sensation may be integrated in the central nervous system. Both nociceptive and gravitational sensations are critical for the preservation of the species in animals.