The pharmacology of efferent synapses in the lateral-line system of Xenopus laevis.
نویسنده
چکیده
The sensory hair-cells of the acoustico-lateralis system of sense organs have been shown, in the majority of cases, to receive efferent innervation. Studies on the ultrastructure of the sensory epithelium in the inner ear (Wersall, 1956; Engstrom, 1958) gave the first clear demonstration of vesiculated nerve terminals in synaptic contact with the membranes of hair-cells. From their similarity with axon-dendritic synapses in the central nervous system they were thought to be efferent (Engstrom, 1958). Degeneration experiments have confirmed this (Engstrom & Fernandez, 1961). Subsequent ultrastructural studies on the hair-cells of other members of the acousticolateralis system including the lateral-line receptors (Hama, 1962; Flock, 1965, 1967) have also revealed vesiculated nerve terminals in synaptic contact with their membranes. Electrical stimulation of efferent fibres to the cochlea (Galambos, 1956; Fex, 1962) inhibits impulse activity in afferent fibres in the eighth nerve. Recently the inhibitory nature of efferent fibres to the lateral-line organs has also been demonstrated in the clawed toad Xenopus laevis (Russell, 1968, 1970) and in the Japanese sea eel (Katsuki, Haskimoto & Yanagisawa, 1968). In Xenopus, however, stimulation of lateral-line efferent fibres, in the absence of calcium, failed to inhibit afferent impulses. Inhibition was also attenuated or blocked by the presence of D-tubocurarine chloride. These observations have promoted this investigation into the nature of the transmitter released at lateral-line synapses. Its object is to discover what evidence there may be that the transmitter is acetylcholine.
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ورودعنوان ژورنال:
- The Journal of experimental biology
دوره 54 3 شماره
صفحات -
تاریخ انتشار 1971