, ▁and ▁the ▁DA ▁cells ▁sending ▁in hib itory ▁signals ▁to ▁the ▁ip R GC s . ▁These ▁in hib itory ▁signals ▁are ▁medi ated ▁through ▁G AB A , ▁which ▁is ▁co - re leased ▁from ▁the ▁DA ▁cells ▁along ▁with ▁dop am ine . ▁D op am ine ▁has ▁functions ▁in ▁the ▁light - ada pt ation ▁process ▁by ▁up - reg ulating ▁mel an ops in ▁trans cription ▁in ▁ip R GC s ▁and ▁thus ▁increasing ▁the ▁phot ore ceptor ' s ▁sens itivity . ▁In ▁parallel ▁with ▁the ▁DA ▁am ac r ine ▁cell ▁in hib ition , ▁som at ost atin - re le asing ▁am ac r ine ▁cells , ▁themselves ▁in hib ited ▁by ▁DA ▁am ac r ine ▁cells , ▁in hib it ▁ip R GC s . ▁Other ▁syn apt ic ▁inputs ▁to ▁ip R GC ▁d end rit es ▁include ▁cone ▁b ip olar ▁cells ▁and ▁rod ▁b ip olar ▁cells . ▁ ▁Output s ▁ ▁One ▁posts yn apt ic ▁target ▁of ▁ip R GC s ▁is ▁the ▁sup rach ias m atic ▁nucle us ▁( SC N ) ▁of ▁the ▁hypoth al am us , ▁which ▁serves ▁as ▁the ▁circ ad ian ▁clock ▁in ▁an ▁organ ism . ▁ip R GC s ▁release ▁both ▁p itu it ary ▁ad eny ly l ▁cycl ase - activ ating ▁protein ▁( P AC AP ) ▁and ▁gl ut am ate ▁onto ▁the ▁SC N ▁via ▁a ▁mon os yn apt ic ▁connection ▁called