Cocaine intake is associated with testicular toxicity and significantreproductive function impairment. There is accumulating evidencethat cocaine administration can trigger nongenetic inheritancethrough the male germ line affecting development and behavior ofthe offspring. The influence of environmental factors on the epigenomeof male germ cells appears to be most impactful if it happensduring a developmental phase when these cells are epigeneticallyreprogrammed. In the present study, we measured epigenetic marksin isolated germ cells of adult mice treated with cocaine (10 mg/kg) or vehicle, in an intermittent binge protocol (3 i.p. injections, 1h apart, one day on/off for 13 days). We found that chronic cocaineintake disrupts male germ cell epigenetic homeostasis, increasingglobal methylated citocine (5-mC) levels in DNA from germ cells andcauda epididymal sperm (germ cells: vehicle 13.15 ± 0.99 vs cocaine20.113 ± 2.28; sperm: vehicle 15.81 ± 1.08 vs cocaine 21.35± 1.52). Cocaine also increased acetylated histone 4 (H4ac) proteinlevels and decreased class I deacetylases HDAC1/2 mRNA andprotein expression (p<0.05). The mRNA expression levels of classIIa and IIb HDACs were also altered (p<0.05). Immunolocalizationstudies showed that HDAC1/2 were mainly expressed in primaryspermatocytes and H4ac was immunolocalized in late meiotic stagesin vehicle mice while it was detected in primary spermatocytesand in successive stages until round spermatid in cocaine-treatedmice. We observed altered mRNA expression of DNA methylationmarkers in isolated germ cells showing decreased levels of Dnmt3band Tet1 gene expression after cocaine treatment (p<0.05). TET1was mainly immunolocalized in primary spermatocytes in vehicleand cocaine-treated mice. The results presented here broaden thebasic knowledge of the impact of addictive stimulants on testicularpathophysiology, fertility and male reproductive health and implythat altered epigenetic homeostasis by cocaine may have potentialconsequences on future generations.Fil: Gonzalez, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Gambini Pantoja, Camilo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Vitullo, Alfredo Daniel. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bisagno, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Gonzalez, Candela Rocio. Universidad Maimónides. Área de Investigaciones Biomédicas y Biotecnológicas. Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y de Diagnóstico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaLXIII Reunión Anual de la Sociedad Argentina de Investigación Clínica, LXVI Reunión Anual de la Sociedad Argentina de Inmunología y Reunión Anual de la Asociación Argentina de FisiologíaMar del PlataArgentinaSociedad Argentina de Investigación ClínicaSociedad Argentina de InmunologíaAsociación Argentina de FisiologíaAsociación Argentina de VirologíaAsociación Argentina de Nanomedicinas