RESUMEN
OBJECTIVES: This study determined the association between expression of the endoplasmic reticulum (ER) stress sensor mRNA in the peripheral leukocytes and the patterns of kratom use and evaluated the correlations between the levels of the ER stress sensor mRNA and the severity of kratom dependence and kratom induced depressive symptoms among people who use kratom (PWUK). METHODS: A total of 20 PWUK and 20 age matched non-kratom using healthy controls were recruited. Data collected from PWUK included patterns of kratom use, severity of kratom dependence, and severity of depressive symptoms during abstinence from kratom. The mRNA expression of binding immunoglobulin protein ( BiP ), X-box binding protein 1, activating transcription factor 4, and C/-EBP homologous protein ( CHOP ) (major indicators of ER stress response) were analyzed using quantitative reverse transcription polymerase chain reaction in leucocyte-derived total RNA sample of the participants. RESULTS: PWUK regardless of their pattern of kratom use recorded significantly higher expression of BiP mRNA compared with controls. Expression of CHOP mRNA was only significantly higher in those who first consumed kratom at the age of 18 years and above and those who have been using kratom for longer than 6 years, compared with controls. Higher expression of BiP , ATF4 , and CHOP mRNA were significantly positive correlated with greater severity of kratom dependence. Although only higher expression of BiP and CHOP mRNA were significantly positively correlated with greater severity of depressive symptoms. CONCLUSIONS: Regular kratom consumption may activate the ER stress pathway and there may be a link between altered ER stress response and kratom dependence and kratom induced depressive symptoms.