ObjectiveTo investigate the expression and distribution changes of G protein-gated inwardly rectifying potassium （GIRK） channel subunits GIRK1 and GIRK2 following morphine tolerance using human embryonic kidney 293 （HEK293） cells. MethodsHEK293 cells were transfected with the lentiviral vector pLV-CMV-GIRK1-T2A-GIRK2-P2A-MOR to establish a stable cell line overexpressing GIRK1， GIRK2， and the μ-opioid receptor （MOR）.Morphine （1 μmol/L， 24 h） was applied to these stable cells to construct a morphine-tolerant HEK293 cell model.Cellular immunofluorescence was used to examine the distribution and co-localization of MOR with GIRK1 and GIRK2.ELISA was performed to measure cAMP levels to confirm the establishment of the morphine-tolerant model.Cellular immunofluorescence and Western blot were employed to analyze the distribution and protein expression changes of GIRK1 and GIRK2 after morphine tolerance.A multimode microplate reader was used to measure fluorescence intensity for detecting changes in cellular membrane potential following morphine tolerance. ResultsIn the stable HEK293 cells， immunohistochemistry showed that GIRK1 and GIRK2 were primarily expressed on the plasma membrane， with minimal presence in the cytoplasm.Both GIRK1 and GIRK2 co-localized with MOR and with each other.Compared with the control group， cAMP levels significantly decreased after 1 h of morphine treatment （1.42±0.07 vs.0.72±0.12， P=0.001 0）， while they significantly increased after 24 h of treatment （0.72±0.12 vs.1.98±0.17， P=0.000 5）.Fluorescence double staining revealed that after 24 h of morphine treatment， the morphine-tolerant group showed a significant increase in cytoplasmic GIRK1 （13.76±7.67 vs.63.72±16.02， P＜0.000 1） and GIRK2 （7.16±2.61 vs.32.92±7.67， P=0.002 9）.Western blot analysis indicated that the expression of membrane proteins GIRK1 （1.11±0.14 vs.0.85±0.01， P=0.004 5） and GIRK2 （1.32±0.02 vs.0.86±0.08， P=0.000 1） was significantly downregulated after morphine tolerance.Membrane potential measurements showed that the hyperpolarization response in morphine-tolerant cells was significantly attenuated （-15.53±0.12） % vs.（-8.17±0.11） %， P＜0.000 1. ConclusionChronic morphine treatment can induce downregulation of GIRK1 and GIRK2 expression on the plasma membrane in stable HEK293 cells.

Objective To explore the humoral and cellular immune responses of a vaccine of S fragments from a new type reovirus R4 strain in mice.Methods Four recombinant plasmids were constructed by respectively cloning S 1, S2, S3,S4 genes into pcDNA3.1+, and mice were intramuscularly immunized with the recombinant plasmids in a dose of 100 μg/mouse.Control vector pcDNA3.1 +and phosphate buffered saline (PBS) were used as negative controls.The spe-cific antibody level and IgG subclass (IgG1, IgG2a, and IgG2b) were detected by ELISA, and cellular immune responses to R4 were assessed using an interferon ( IFN)-γELISpot assay .Results All recombinant plasmids induced significantly higher levels of anti-R4 IgG compared with that of the controls (pcDNA3.1 +and PBS), and the titers were highest in the mice immunized with S1 and S3.On the other hand, S1 gene induced highest IgG2a antibody and the cellular immune re-sponse was best .Conclusions After the mice immunized with S 1 gene recombinant plasmid , this plasmid can initiate both cellular and humoral immune responses in mice .S1 gene recombinant plasmid is a promising vaccine candidate .