Catecholaminergic structures in the nervous system of three nematode species, with observations on related enzymes

Abstract

The formaldehyde fluorescence technique has been used to demonstrate amine‐specific fluorescence in the nervous system of three nematode species, Prionchulus punclatus Cobb, Panagrellus redivivus Goodey, and Aphelenchus avenae Bastian. Examination of some of the physical and chemical properties of this fluorescence has shown it to be due principally to the primary catecholamine dopamine. Dopamine and dopa decarboxylase were also detected biochemically in A. avenae. Dopamine has now been proposed as a putative neurotransmitter in a number of nematode species and the role of this and other biogenic amines in nematodes is discussed. Of the two principal enzymes involved in the metabolism of monoamines, catechol‐O‐methyltransferase was detected in both A. avenae and P. redivivus but monoamine oxidase could not be detected in these or other nematode species.

Improved visualization of dopaminergic neurons in nematodes using the glyoxylic acid fluorescence method

“…The results described in this paper give a more detailed description of the dopaminergic neurons in the nervous system of small nematodes than that illustrated previously (Sulston, Dew et al, 1975;Hogger, Estey et al, 1978;Wright & Awan, 1978). Indeed, the dopaminergic component of the anterior nervous system of P. redivivus and T. colubriformis (Fig.…”

“…I ; Plate I(a), (b), (c)) has been shown to contain all of the elements revealed in Cuenorhabditis elegans by the elegant work of Sulston, Dew et al (1975), which required the examination of serial sections by electron microscopy (Ward, Thomson et al, 1975) to support the rather diffuse image obtained with the FIF method, using transmitted light. Wright & Awan (1978) were forced to conclude that the dopaminergic neurons in P . redivivus could not be identified in the absence of ultrastructural evidence but techniques described in this work overcome this limitation.…”

“…Hogger, Estey et al (1978) did not identify the catecholamine involved but Wright & Awan (1978) confirmed the presence of dopamine by biochemical assay. However, Wright & Awan (1978) were unable to detect fluorescence in P. redivivus except in or near the nerve ring and they considered identification of dopaminergic neurons was not possible in this nematode in the absence of ultrastructural evidence. Such a requirement places a severe limitation on the value of the technique for small nematodes and it became important to overcome this difficulty for work on the possible mode of action of certain anthelmintics on the nematode nervous system.…”

“…This nematode is also much larger than those used in this and other previous studies. Recently ,Hogger,Estey & Croll(l978) used the FIF method to demonstrate catecholamines in the nervous system of Xiphinenia americanuni and Wright & Awan (1978) used this method to demonstrate dopamine in the nerve ring of the small nematodes Aphelenchus avenue, Prinochulits punctatus and Panagrellus redivivus. Hogger, Estey et al (1978) did not identify the catecholamine involved but Wright & Awan (1978) confirmed the presence of dopamine by biochemical assay.…”

“…Recently ,Hogger,Estey & Croll(l978) used the FIF method to demonstrate catecholamines in the nervous system of Xiphinenia americanuni and Wright & Awan (1978) used this method to demonstrate dopamine in the nerve ring of the small nematodes Aphelenchus avenue, Prinochulits punctatus and Panagrellus redivivus. Hogger, Estey et al (1978) did not identify the catecholamine involved but Wright & Awan (1978) confirmed the presence of dopamine by biochemical assay. However, Wright & Awan (1978) were unable to detect fluorescence in P. redivivus except in or near the nerve ring and they considered identification of dopaminergic neurons was not possible in this nematode in the absence of ultrastructural evidence.…”