Contributions to the mechanism of triptamine effect on the adductor activity of fresh-water mussel larvae

Lábos, Elemér (1966) Contributions to the mechanism of triptamine effect on the adductor activity of fresh-water mussel larvae. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 33. pp. 13-35. ISSN 0365-3005

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Abstract

The rhythmic motoric activity induced by tryptamine of the glochidia of the fresh water mussel (Anodonta cygnea L.) was examined alone and in the presence of various pharmacons. For the modeling of the rhythm a counting off mechanism was assumed. The cause of the subsiding of the rhythm could not be the development of indole acetic acid, because this agent potentiates the tryptamine effect. By the examination of various indole derivatives we stress te specificity of the tryptamine effect. In concentrations of 10⁻⁴-10⁻³ M/lit 5-methoxy —tryptamine and eserine are indole derivatives of minor action but effective. Indole alkylic acids, melatonine, bufotenine are ineffective. To explain the reduction of sensitivity observed with the progress of ontogey we assumed the development of a new mediator system. This can not be a cholinergic, GABA-ergic, glutaminergic system, since ACh.GABA, glutamine do not inhibit the activity caused by tryptamine. The application of sympathicolythica, however, argues for the development of a catecholamine inhibiting system. Dibenamine and ergotamine potentiate the tryptamine effect. Dichlor-isoproternol in itself is of activating and given together with tryptamine of potentiating effect. Of the catecholamines examined adrenaline, noradrenaline, IPNA are potentiating, while at tryptamine insensitive population dopamine, DOPA, α-methyl-DOPA are ineffective. Thus, the inhibiting catecholamine which can be made responsible for the activating effect of the sympat holy tics is not among these. It can be assumed that in the course of ontogeny also inhibiting and activating systems based on adrenergic mediation develop. The effects of NaN₃ KCN and the inhibiting action of 2,4-DNP stress the importance of the oxidative metabolic processes. The mechanism of the azide action was discussed. The cyanide effect suggests the direct role of terminal oxidation. Photo-activation developed in a special incubation mixture (tryptamine + methionine + mono-iodo-acetic acid) also assumes the participation of a coloured (cytochromic?) system and stresses the importance of mechamisms with free radicals. Action with indole-compounds can be demonstrated also on the morphogenesis of earlier embryonal forms. Tryptamine is also here of outstanding effect and in 100 µg/ml concentration brings about dysmorphogenesis, sweling and desintegration.

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