Are there any links between depression and the mechanism (pharmacological action) of isotretinoin in the body? if so, please elaborate on this topic:)

Many possibilities: Section 3.3 "biological plausibility" of the linked review paper by bremner et al, 2012: http://www.Ncbi.Nlm.Nih.Gov/pmc/articles/pmc3276716/ retinoic acid via gene expression has a broad range of effects on the brain, all can lead to mood changes. Although the exact mechanism has not been worked out, bremner et al provides a concise summary of current understanding.