The nervous system control of lateral ciliary activity of the gill of the bivalve mollusc, Crassostrea virginica

Abstract

Lateral cilia of the gill of Mytilus edulis are controlled by a reciprocal serotonergic-dopaminergic innervation from their ganglia. Other bivalves have been studied to lesser degrees and lateral cilia of most respond to serotonin and dopamine when applied directly to the gill indicating a possible neuro or endocrine mechanism. Lateral cilia in Crassostrea virginica are affected by serotonin and dopamine, but little work has been done regarding ganglionic control of their cilia. We examined the role of the cerebral and visceral ganglia in innervating the lateral ciliated cells of the gill epithelium of C. virginica. Ciliary beating rates were measured in preparations which had the ipsilateral cerebral or visceral ganglia attached. Superfusion of the cerebral or visceral ganglia with serotonin increased ciliary beating rates which was antagonized by pretreating with methysergide. Superfusion with dopamine decreased beating rates and was antagonized by ergonovine. This study demonstrates there is a reciprocal serotonergic-dopaminergic innervation of the lateral ciliated cells, similar to that of M. edulis, originating in the cerebral and visceral ganglia of the animal and this preparation is a useful model to study regulatory mechanisms of ciliary activity as well as the pharmacology of drugs affecting biogenic amines in nervous systems.

Fig. 1

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to serotonin applied directly to excised gill with and without MS (10⁻⁵M). Statistical analysis was determined by student’s t-test. ^ap < 0.01. N = 5 for each set.

Fig. 2

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to superfusion of serotonin to the visceral ganglia of VG Preparations with and without methysergide added to the VG. Statistical analysis was determined by t-test. ^ap < 0.01.

Fig. 3

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to superfusion of serotonin to the cerebral ganglia of CG Preparations with and without methysergide added to the CG. Statistical analysis was determined by a t-test. ^ap < 0.01.

Fig. 4

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to dopamine applied directly to excised gill with and without ERG (10⁻⁵M). The gill was activated with 10⁻⁵M serotonin when dopamine was tested. Statistical analysis was determined by t-test. ^ap < 0.01.

Fig. 5

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to superfusion of dopamine to the visceral ganglia of VG Preparations with and without ergonovine in the gill chamber. The gill was activated with 10⁻⁵M serotonin when dopamine was tested. Statistical analysis was determined by t-test. ^ap < 0.01

Fig. 6

The changes in beating rates (beats/s ± SEM) of lateral cilia in response to superfusion of dopamine to the cerebral ganglia of CG Preparations with and without ergonovine added to the CG. The gill was activated with 10⁻⁵M serotonin when dopamine was tested. Statistical analysis was determined by t-test. ^ap < 0.01.

Fig. 7

Schematic of the innervation of the lateral cilia by the cerebral and visceral ganglia via the cerebrovisceral connective and the branchial nerve.