▁February ▁ 1 9 7 5 . ▁ ▁See ▁also ▁▁ ▁Hav re ▁Mountains ▁ ▁L ass us ▁Mountains ▁ ▁Wal ton ▁Mountains ▁ ▁References ▁ ▁Category : Mount ain ▁ranges ▁of ▁Alexander ▁Island <0x0A> </s> ▁The ▁alpha - 2 C ▁ad r ener g ic ▁re ceptor ▁( α 2 C ▁ad reno ceptor ), ▁also ▁known ▁as ▁AD RA 2 C , ▁is ▁an ▁alpha - 2 ▁ad r ener g ic ▁re ceptor , ▁and ▁also ▁denotes ▁the ▁human ▁gene ▁encoding ▁it . ▁ ▁Re ceptor ▁▁ ▁Al pha - 2 - adr ener g ic ▁re cept ors ▁include ▁ 3 ▁highly ▁hom olog ous ▁sub types : ▁alpha 2 A , ▁alpha 2 B , ▁and ▁alpha 2 C . ▁These ▁re cept ors ▁have ▁a ▁critical ▁role ▁in ▁reg ulating ▁ne uro trans mit ter ▁release ▁from ▁sympath etic ▁n erves ▁and ▁from ▁ad r ener g ic ▁neur ons ▁in ▁the ▁central ▁nerv ous ▁system . ▁Studies ▁in ▁m ice ▁revealed ▁that ▁both ▁the ▁alpha 2 A ▁and ▁alpha 2 C ▁sub types ▁were ▁required ▁for ▁normal ▁pres yn apt ic ▁control ▁of ▁transmit ter ▁release ▁from ▁sympath etic ▁n erves ▁in ▁the ▁heart ▁and ▁from ▁central ▁nor adr ener g ic ▁neur ons ; ▁the ▁alpha 2 A ▁sub type ▁in hib ited ▁transmit ter ▁release ▁at ▁high ▁stim ulation ▁frequencies , ▁whereas ▁the ▁alpha 2 C ▁sub type ▁mod ulated ▁ne uro trans mission ▁at ▁lower ▁levels ▁of ▁n erve ▁activity . ▁ ▁Gene