AIM:To investigate the effects of cigarette smoke exposure during adolescence on the inflammato-ry response mediated by microglia in the prefrontal cortex of mice,and its impact on learning and memory functions in adulthood.METHODS:72 two-week-old healthy male Kunming mice,with each weighing(11.0±1.5)g,were random-ly divided into control and cigarette exposure groups(n=36 per group).The mice in the cigarette exposure group were pas-sively exposed to 6 cigarettes daily for 10 weeks.At three time points of 4-week-old(infancy),8-week-old(adoles-cence),and 12-week-old(adulthood),six mice were selected from each group to have their neurobehavioral and patholog-ical changes examined.In particular,the step-down test,three-chamber social interaction test,and novel object recogni-tion test were used to detect changes in learning and memory abilities and cognitive behavior.Immunofluorescence testing was performed to detect the morphology,number of synapses,and expression of inflammatory factor apoptosis-associated speck-like protein containing a CARD(ASC)around the microglial cells in the prefrontal cortex of mice in each group.Western blot was performed to assess the expression levels of synaptophysin(SYP)and postsynaptic density protein-95(PSD-95)in the cerebral cortex of mice in each group.Enzyme-linked immunosorbent assay(ELISA)was performed to detect the protein expression of tumor necrosis factor-α(TNF-α),interleukin 1β(IL-1β),and IL-6 in the prefrontal cor-tex.RESULTS:(1)In the step-down test,the latency of mice at 8 and 12 weeks of age was significantly shortened,and the number of errors was significantly increased in the cigarette exposure group compared with the age-matched control group(P＜0.01).In addition,the social recognition time and exploration time for novel objects were prolonged(P＜0.05).(2)Immunofluorescence assays revealed that exposure to cigarette smoke in mice,at both 8 and 12 weeks of age,resulted in a reduction of SYP-positive puncta within the prefrontal cortex.Concurrently,there was an observed increase in the number of Iba1-positive microglia,which exhibited an activated phenotype,as well as an elevation in ASC-positive puncta in proximity to the microglia.Western blot further revealed reduced expression of synaptophysin protein SYP and PSD-95 in the cerebral cortex of the mice at 8 and 12 weeks of age in the cigarette exposure group(P＜0.05).(3)ELISA showed increased levels of inflammatory factors TNF-α,IL-1β,and IL-6 in the prefrontal cortex of the mice at 8 and 12 weeks of age in the cigarette exposure group(P＜0.05).CONCLUSION:Exposure to cigarette smoke during adoles-cence in mice may result in the enhanced secretion of inflammatory factors through the activation of microglia in the pre-frontal cortex.This activation can alter microglial function and induce synaptic damage,consequently impairing learning,memory,and cognitive abilities in adulthood.

AIM:To investigate the effects of cigarette smoke exposure during adolescence on the inflammato-ry response mediated by microglia in the prefrontal cortex of mice,and its impact on learning and memory functions in adulthood.METHODS:72 two-week-old healthy male Kunming mice,with each weighing(11.0±1.5)g,were random-ly divided into control and cigarette exposure groups(n=36 per group).The mice in the cigarette exposure group were pas-sively exposed to 6 cigarettes daily for 10 weeks.At three time points of 4-week-old(infancy),8-week-old(adoles-cence),and 12-week-old(adulthood),six mice were selected from each group to have their neurobehavioral and patholog-ical changes examined.In particular,the step-down test,three-chamber social interaction test,and novel object recogni-tion test were used to detect changes in learning and memory abilities and cognitive behavior.Immunofluorescence testing was performed to detect the morphology,number of synapses,and expression of inflammatory factor apoptosis-associated speck-like protein containing a CARD(ASC)around the microglial cells in the prefrontal cortex of mice in each group.Western blot was performed to assess the expression levels of synaptophysin(SYP)and postsynaptic density protein-95(PSD-95)in the cerebral cortex of mice in each group.Enzyme-linked immunosorbent assay(ELISA)was performed to detect the protein expression of tumor necrosis factor-α(TNF-α),interleukin 1β(IL-1β),and IL-6 in the prefrontal cor-tex.RESULTS:(1)In the step-down test,the latency of mice at 8 and 12 weeks of age was significantly shortened,and the number of errors was significantly increased in the cigarette exposure group compared with the age-matched control group(P＜0.01).In addition,the social recognition time and exploration time for novel objects were prolonged(P＜0.05).(2)Immunofluorescence assays revealed that exposure to cigarette smoke in mice,at both 8 and 12 weeks of age,resulted in a reduction of SYP-positive puncta within the prefrontal cortex.Concurrently,there was an observed increase in the number of Iba1-positive microglia,which exhibited an activated phenotype,as well as an elevation in ASC-positive puncta in proximity to the microglia.Western blot further revealed reduced expression of synaptophysin protein SYP and PSD-95 in the cerebral cortex of the mice at 8 and 12 weeks of age in the cigarette exposure group(P＜0.05).(3)ELISA showed increased levels of inflammatory factors TNF-α,IL-1β,and IL-6 in the prefrontal cortex of the mice at 8 and 12 weeks of age in the cigarette exposure group(P＜0.05).CONCLUSION:Exposure to cigarette smoke during adoles-cence in mice may result in the enhanced secretion of inflammatory factors through the activation of microglia in the pre-frontal cortex.This activation can alter microglial function and induce synaptic damage,consequently impairing learning,memory,and cognitive abilities in adulthood.