Pathophysiology help with Major Depressive Disorder

Hi guys, i'm currently starting to work on my concept map before the semester ends for Christmas, and I need some help. I am doing my concept map on "Major depressive disorder" (MDD). I am struggling to construct the patho in such a way that isn't just a slew of word vomit consisting of Serotonin, dopamine...etc. I need to get the pathophysiology down to the "cellular level" so basically the level of the neurotransmitters If anyone has any suggestions it would be greatly appreciated.