[Antagonistic effect of electro-acupuncture analgesia with Ca2+ injection into habenula could be reversed by gallamine triethiodide].

.1 mol/L CaCl2 0.5 microliters, 0.06 mol/L ACh 0.5 microliters, 5.4 x 10(-3) mol/L gallamine triethiodide (cholinergic nicotinic receptor blocker) 0.5 microliter and 14.4 x 10(-3) mol/L atropine (cholinergic muscarinic receptor blocker) 0.5 microliter were injected through bilateral intracranial cannulae in rat habenula. Pain threshold was measured by the latency of tail-flick reflex elicited by radiant heat exposure before and after intracerebral injection. CaCl2 significantly reduced the basic pain threshold and weakened the effect of the acupuncture analgesia. ACh apparently antagonized the effect of acupuncture analgesia. Gallamine triethiodide could recover the pain threshold almost to the raised level by acupuncture, but atropine only strengthened the effect on pain threshold weakly and briefly. The results suggest that the antagonistic effect of Ca2+ may be mediated via ACh in habenula.