Study on neurohormonal modulation of both somatic motor and circulatory systems in decapod Crustacea.

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The aim of this study was to clarify physiological functions of the pericardial organs developped in decapod Crustacea. To study these, te spiny lobster (Panulirus japonicus) and the american crayfish (Procambarus clarkii) were used. Behaviors of them were observed with video-recording systems. Blood pressure and electrical activities of nerve and muscle were recorded with conventional methods for electrophysiology. Main results are as follows.1. Using a couple of electrodes and a pressure sensor implanted in the body, I succeeded in simultaneous recording of electrocardiogram and blood pressure in the pericardial cavity while various behaviors are recorded.2. Using the cardioarterial valves, it was demonstrated that serum of the lobster contained three substances which show the same activities as pericardial hormones (octopamine, proctolin and serotonin), and that their concentrations were as high as 0.1 M (physiologically significant).3. Cardiac pumping activities in vivo were slowly … More increased after an injection of octopamine or proctolin (lower than 1 M). Similar increases in cardiac pumping activities were observed during vigorous body movements, such as feeding and escape behaviors. This may imply that octopamine or proctolin secretes during vigorous body movements.4. Each of serotonin, octopamine and proctolin showed specific modulatory actions on spontaneous activities of the ventral ganglia, especially on swimming activities of the crayfish. Serotonin enhanced impulse activity of power stroke motoneurons innervating swimmerets. Octopamine suppressed impulses of both power and return stroke motoneurons whereas proctolin activated them.5. I succeeded in recording impulse activities of ligament nerves which are related to secretion of the pericardial neurohormones. Some (usuall three) axons in the ligament nerves started to fire when the pericardial cavity was perfused with cold saline (5-15゜C). Ligament nerves also fired when serotonin or octopamine (u mM, 1 ml) was applied into the pericardial cavity. Less