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Morphological and physiological properties of the dorsal unpaired median neurons of the cockroach metathoracic ganglion

1988; Elsevier BV; Volume: 91; Issue: 1 Linguagem: Inglês

10.1016/0300-9629(88)91589-7

0300-9629

Yoshitaka Tanaka, Hiroshi Washio,

Insect Utilization and Effects

1. The eight dorsal unpaired median (DUM) neurons in the metathoracic ganglion of the cockroach, Periplaneta americana, were divided into six different types on the basis of the branching of their axons which were revealed by intracellular injection of nickel chloride. 2. Direct stimulation of only one DUM neuron (DUM 3,5,6) affected the tetanus tension of the coxal depressor muscle 177d, producing a reduction in the amplitude of tetanus tension and the rise in the basal tension of the muscle. 3. The inhibitory effect of stimulating the DUM neuron on the tension generated in muscle 177d could be mimicked by the application of octopamine. The α-adrenergic blocker, phentolamine, completely blocked the inhibitory effect of stimulating the DUM neuron and of perfusing octopamine on the tetanus tension of muscle 177d. However, it failed to block the increase in the basal tension. Therefore, the inhibitory effect of the DUM neuron may be mediated by octopamine. 4. In relation to the increase in basal tension, the possible synaptic mechanism of DUM neurons has been discussed.