Paternal methylphenidate exposure alters sperm miRNAs and induces intergenerational behavioral and transcriptional changes that are largely reversed by washout

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity. Methylphenidate (MPH), a first-line medication, is often used long-term and not routinely discontinued in individuals planning to have children. Guided by the Paternal Origins of Health and Disease framework, in this study, we investigated intergenerational effects of paternal MPH exposure and reversibility of sperm epigenetic changes. Male BALB/c mice received MPH (15 mg/kg) or vehicle for 28 days and were mated with untreated females immediately after treatment (F0-T1) or after a 40-day washout period (F0-T2). Behavioral tests and brain gene expression analyses were conducted in the offspring (F1), and sperm small noncoding RNA (sncRNA) profiles were examined in F0 males. Male offspring in the F0-T1-MPH group showed increased open-arm entry into the elevated plus maze and reduced expression of Maoa, Maob, and Bdnf in the medial prefrontal cortex. These changes were absent in the offspring derived from the F0-T2-MPH group. Sperm sncRNA sequencing identified 5,684 differentially expressed fragments in F0-T1-MPH mice, including marked alterations in miRNA-derived fragments, such as miR-34c-5p and miR-30e-5p. The target genes of these altered miRNAs were enriched in ADHD-related pathways, including axon guidance and Rap1 signaling. After washout, the number of differentially expressed sncRNA fragments decreased to 665, whereas the number of altered miRNA-derived fragments decreased from 383 to 7. These findings suggest that paternal MPH exposure may influence offspring behavior and brain gene expression through sperm miRNA alterations and that these effects are largely reversible following drug withdrawal.