Serotonin-immunoreactivity in peripheral tissues of the opisthobranch molluscsPleurobranchaea californicaandTritonia diomedea

Abstract

The distribution of serotonin (5-HT)-immunoreactive elements in peripheral organs of the sea-slugs Pleurobranchaea californica and Tritonia diomedea was studied in cryostat sections. For Pleurobranchaea, 5-HT-immunoreactive (5-HT-IR) neuron cell bodies were found only in the central nervous system (CNS); 5-HT-IR cell bodies were not observed in foot, tentacles, rhinophores, oral veil, mouth, buccal mass, esophagus, gills, salivary glands, skin, reproductive system, and acidic glands, nor in peripheral tentacle and rhinophore ganglia. However, 5-HT-IR neuronal processes were widely distributed in these structures and the patterns of 5-HT-IR elements were characteristic for each particular peripheral tissue. 5-HT-IR elements were most dense in the sole of the foot and the reproductive system, followed by rhinophores, tentacles, oral veil, mouth, buccal mass, and esophagus. The sensory epithelium of rhinophores, tentacles, and mouth showed a highly structured glomerular organization of 5-HT-IR fibers, suggesting a role for 5-HT in sensory signaling. A much lower density of 5-HT-IR innervation was observed in gills, skin, salivary, and acidic glands. 5-HT-IR was observed in neuropil of tentacle and rhinophore ganglia with many transverse 5-HT-IR axons running to peripheral sensory areas. The distribution of 5-HT-IR elements in Tritonia was similar to that of Pleurobranchaea. A significant suggestion of the data is that central serotonergic neurons may modulate afferent pathways from sensory epithelia at the periphery.

Monoamines in the pedal plexus of the land snail Megalobulimus oblongus (Gastropoda, Pulmonata)

“…Neurotransmitters such as acetylcholine, dopamine and serotonin (5-HT), diverse neuropeptides such as substance P and calcitonin gene-related peptide have been identified (3,6,7). There is some disagreement regarding the presence of monoaminergic or peptidergic neuronal somata in the foot (8).…”

Putative lateral inhibition in sensory processing for directional turns

“…We presume that branchlets of LOVN and TN coinnervate some of the ganglia. Inhibitory interactions among sensory afferents or interneurons could take place in the small glomerular, ganglion-like structures associated with the sensory afferents or in the nearby subepithelial meshworks associated with sensory epithelium (Moroz et al 1997). More exact details of synaptic interconnections in the oral veil demand a greatly more detailed study of anatomy and physiology.…”

Functional neuroanatomy of the rhinophore of Archidoris pseudoargus

“…051007) in PBS with 0.2% Triton X-100 and 2% NGS overnight at room temperature. This antibody was used successfully in previous studies in gastropod molluscs (Croll et al 2003;Moroz et al 1997;Wertz et al 2006). After Wve rinses in PBS, sections were incubated in Alexa Fluor 488-conjugated goat anti-rabbit secondary antibody (1:250, Molecular Probes, Eugene, OR, USA, Cat.…”

“…In A. punctata, the rhinophore ganglion and the glomeruli are innervated by centrifugal serotonergic processes (Wertz et al 2006). Similar to results in the opisthobranchia Pleurobranchaea and Tritonia (Moroz et al 1997) and sensory organs in Phestilla, serotonergic cell bodies were shown to be absent in the periphery (Croll et al 2003).…”