Meeting Abstract
Histamine (HIS) is a biogenic amine serving as a neurotransmitter in nervous systems and sensory receptors in invertebrates. HIS has rarely been reported in bivalves. We previously showed it is involved in sensory-motor integration of gill lateral cell cilia beating in the bivalve Crassostrea virginica. We also used HPLC to show it is present in ganglia and tissues. We hypothesize HIS neurons and HIS receptors are present C. virginica. We used immunohistofluorescence with primary antibodies to HIS and HIS receptors, and fluorescently labeled secondary antibodies to visualize HIS and HIS receptors in ganglia, gill and mantle. Tissues were dissected, snap frozen, cryostat sectioned, fixed with EDAC (N-Ethyl-N’-(3-dimethylaminopropyl) carbodiimide hydrochloride) or paraformaldehyde, treated with blockers, and incubated with primary and secondary antibodies. Whole mounts of gill and mantle were similarly treated. Cryostat sections and whole mounts were viewed with a Zeiss epilume fluorescence microscope with a ProgRes C3 camera, as well as a Leica epilume fluorescence microscope with a Leica DFC400 camera. Both scopes had FITC and Texas Red excitation/emission filters. Results show HIS and HIS H2 receptors present in visceral ganglia gill, mantle body and sensory tentacles of the mantle rim. Of particular significance is their presence in sensory tentacles as that correlates well with our sensory physiology studies, and their presence in gill interfilamental junctions, the physiology of which has not been well described. This project confirms the identity of HIS and H2 receptors in the nervous system and innervated organs, and coupled with our other work shows HIS to be an important endogenous biogenic amine in the bivalve C. virginica.
