Bariatric Sleeve surgery and affects to neurotransmitters, etc

Waiting for a surgery date for gastric sleeve.  Im having second thoughts.  Im requesting help..Ive asked my Primary doctor and the surgeon to answer this question and they seem to only know how appetite is affected and not how lowering Ghrelin Levels might affect other areas of the body.  Ive been reading but not really understanding (since I have no medical background) that Ghrelin affects things such as dopamine levels in the brain.  If dopamine goes too low we can get parkinsins, lack of concentration, and all sorts of other problems.  From what Im reading is that Ghrelin also helps artery wall, cell and all sorts of other parts of our bodies beside our hunger.

Is this true?  How would cutting 90% of the stomach affect neurotransmitters like dopamine, seratonin,,I also  get migraines....how do we know if how Ghrelin and dopamine levels are already too low.  Having the sleeve may cause problems.  Will the sleeve cut out all production of Ghrelin and/dopamine?  
I have the sleeve scheduled but I am having second thoughts.  
Any doctors out there?  Please help.  Am i overworrying about this?  Can these problems be solved if they do result later in life?