The antidepressant venlafaxine induces upregulation of miR-92 and histological alterations in a chicken embryo model

Antidepressants are commonly prescribed for treating anxiety disorders and depression, including pregnant patients. These medications influence the absorption and metabolism of key neurotransmitters such as serotonin, norepinephrine, and dopamine. However, many aspects of antidepressant function remain unclear, especially regarding their impact on neurodevelopment when used during pregnancy. To explore this, we employed a 3R-friendly chicken embryo model to investigate the cellular and molecular implications of antidepressants use. We focused on commonly used antidepressants for the study: escitalopram, which is a selective serotonin reuptake inhibitor; and venlafaxine, a serotonin and noradrenaline reuptake inhibitor, both of which are frequently prescribed during pregnancy.

Drug distribution analysis showed that both antidepressant drugs reached clinical concentrations in the brain of developing chicken embryos and persisted for several hours. High-throughput miRNA-sequencing showed that venlafaxine upregulated 13 different miRNAs in the chicken cerebellum. Specifically, miR-92 and its human ortholog, miR-363, were significantly upregulated in chicken cerebellum and neuronally differentiated human SH-SY5Y cells, respectively. Neurite metrics showed a significant reduction in neurite outgrowth with venlafaxine, but not with escitalopram. Furthermore, venlafaxine caused histological alterations, such as increased white matter and reduced thickness of the cortical and molecular layer in the cerebellum. Both drugs reduced the thickness of the external granular layer and the number of mitotic events, impacting this crucial germinal zone of the brain.

These findings highlight distinct neurodevelopmental effects of escitalopram and venlafaxine and raise awareness for potential adverse neurological effects in offspring exposed to antidepressants in utero.