http://www.deplin.com/DeplinFacts,HowItWorksAccording to the Deplin website it aids in the production of dopamine, norepinephrine and serotonin. It doesn't mention any interaction or effect on the opioidergic system or endorphins.
Apparently drug interaction studies for Naltrexone and anything other than opiates haven't been done:
"Studies to evaluate possible interactions between REVIA and drugs other than opiates have not been performed. Consequently, caution is advised if the concomitant administration of REVIA and other drugs is required. "
http://www.rxlist.com/revia-drug.htmSo there's no documented interaction between Deplin and Nal.