Role of Phospholipase C in the Dopamine D2 Signaling Pathway in the Control of Lateral Cilia in Gill of Crassostrea virginica
Authors: Georges Edna , Ernest Krystle J. , Catapane Edward J. , Carroll Margaret A. 
Published: June 2021

Lateral cell cilia of gill of Crassostrea virginica are controlled by serotonergic‐dopaminergic innervations from their ganglia. Dopamine is the neurotransmitter causing cilio‐inhibition, serotonin cilio‐excitation. Previous work of our lab showed the post‐synaptic dopamine receptors present in lateral cells are D2‐type. Dopamine D2 receptors (D2R) are G protein‐coupled metabotropic receptors. Ligand binding to D2R splits its Gi/o protein into the Gβγ and Gαi/o subunits. Gαi/o inhibits adenylyl cyclase; while Gβγ opens GIRK channels, closes L‐type Ca2+ channels and activates phospholipase C (PLC). The inhibition of adenylyl cyclase and subsequent lowering of cAMP is known to slow lateral cilia; however, the role of PLC in the signaling pathway has not been well studied with respect to control of lateral cilia. Using immunohistofluorescence, our lab visualized PLC in lateral cell. In this study we hypothesized that the PLC component of the D2 pathway also plays a role in the cilio‐inhibition. To test this we utilized PLC activators and inhibitors on excised gill to determine their effects on lateral cilia. Cilia beating rates were measured using stroboscopic microscopy. In control gill, applying a dose response of dopamine (10−6 – 10−3M) is cilio‐inhibitory, decreasing beating rates of lateral cilia to 0. Applying m‐3M3FBS (10−5 – 10−4M), a PLC activator, caused a moderate decrease in cilia beating rates. Applying U73122 (10−4M), a phosphatidylinositol 4,5‐bisphosphate specific PLC inhibitor, did not alter cilia beating rates by itself, but did effect the dose response to dopamine (10−5 – 10−3M). In the presence of the inhibitor, while the 10−5M dose of dopamine caused the expected decrease in cilia beating rates, the addition of higher doses of dopamine was unable to reduce beating rates any further. As expected, the drug D609, a PLC inhibitor but specific for phosphatidylcholine, had no effects on cilia beating rates or the actions of dopamine. The results of this study supports our hypothesis that the PLC component of the D2R signal transduction pathway plays a role in the inhibitory control of gill lateral cilia. The results show that both components of the D2R pathway, the adenylyl cyclase component and the PLC component are involved in controlling lateral cilia beating. In humans the D2R signal transduction pathway is significantly involved in the actions of antidepressants, neuroleptics, and drugs of abuse, as well as implicated in neuropsychiatric and neurodegenerative disorders. This physiology study is helpful in furthering the understanding of the pathway and should help to generate further investigations.

Support or Funding Information

This work was supported in part by grant 2R25GM06003 of the Bridge Program of NIGMS, NIH grant K12GM093854‐07A1 IRACDA Program of Rutgers University and 604060048 of PSC‐CUNY.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.