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Role of G βγ G Protein Subunit in the Dopamine D2 Signaling Pathway on Ciliary Activity of Gill Lateral Cells in Crassostrea virginica
Author(s) -
Baxter Kameca,
Carroll Margaret A.,
Catapane Edward J.
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.476.4
Subject(s) - cilium , biology , inhibitory postsynaptic potential , dopamine , g protein , microbiology and biotechnology , anatomy , chemistry , medicine , signal transduction , endocrinology
Gill lateral cell (GLC) cilia of Crassostrea virginica are controlled by serotonin‐dopamine (DA) innervations. The gill is innervated by the branchial nerve which originates in the visceral ganglia. The DA nerves are inhibitory and slow down GLC cilia beating rates. The serotonin nerves are excitatory and speed them up. Previous work of our lab showed the post‐synaptic DA receptors in GLC are D2 type (D2R). The D2R signaling pathway involves inhibition of adenylyl cyclase and the splitting of the G protein into the G βγ and Gα i/o subunits. G βγ activates PLC (phospholipase C). G βγ has not been well studied in bivalves with respect to GLC cilia beating. We hypothesize that the G βγ component of the D2R signaling pathway is involved in slowing down the beating rate of GLC cilia. To test this we determined the effects of a G βγ activator and inhibitor on GLC cilia beating rates using stroboscopic microscopy. We conducted acute experiments testing the effects of the G βγ activator and inhibitor, with and without the presence of DA on excised gill. Ciliary activity of gill lateral cells was measured by stroboscopic microscopy and expressed as beats/min ± sem. We found that applying DA (10 −6 – 10 −3 M) to gill is cilio‐inhibitory, causing a dose dependent decrease of beating rates to 0. Applying guanosine 5′‐O‐(3‐thiotriphosphate) (GTP), a G βγ activator, had a slight inhibitory effect on GLC cilia beating over the range of 10 −7 – 10 −3 M. Adding DA prior to GTP did not significantly alter the actions of GTP. Applying the G βγ inhibitor gallein caused an increase in GLC cilia beating rates when applied after DA. The study shows G βγ does play a role in effecting the beating of GLC cilia. When G βγ is activated it activates PLC and caused a cilio‐inhibitory response. When G βγ is inhibited, the cilia beating rates sped up, even in the presence of DA. In light of the fact that the D2R signaling pathway involves activation of PLC as well as inhibition of the adenylyl cyclase, it appears that the PLC path contributes to the cilio‐inhibition. This study provides new knowledge of the actions of G βγ in the D2R pathway in bivalve gill. Because the D2R pathway is significantly involved in the actions of antidepressants, neuroleptics, and drugs of abuse, as well as being implicated in neuropsychiatric and neurodegenerative disorders, further investigations of the physiological role of D2R using this gill system should be helpful to understand the D2R signaling pathway. 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 .