associ ated ▁g ly cop rote in ▁acts ▁via ▁the ▁re cept ors ▁Ng R 2 , ▁GT 1 b , ▁Ng R 1 , ▁p 7 5 , ▁T RO Y ▁and ▁L ING O 1 . ▁O M g p ▁– O lig od end ro cy te ▁my elin ▁g ly cop rote in ▁E ph rin ▁B 3 ▁functions ▁through ▁the ▁E ph A 4 ▁re ceptor ▁and ▁in hib its ▁rem y el ination . ▁S ema ▁ 4 D ( Sem ap hor in ▁ 4 D ) ▁functions ▁through ▁the ▁P lex in B 1 ▁re ceptor ▁and ▁in hib its ▁rem y el ination . ▁S ema ▁ 3 A ▁( Sem ap hor in ▁ 3 A ) ▁is ▁present ▁in ▁the ▁scar ▁that ▁forms ▁in ▁both ▁central ▁nerv ous ▁system ▁and ▁peri pher al ▁n erve ▁inj uries ▁ ▁and ▁cont ributes ▁to ▁the ▁out g row th - in hib itory ▁properties ▁of ▁these ▁sc ars ▁ ▁C lin ical ▁treat ments ▁ ▁S urg ery ▁S urg ery ▁can ▁be ▁done ▁in ▁case ▁a ▁peri pher al ▁n erve ▁has ▁become ▁cut ▁or ▁otherwise ▁divided . ▁This ▁is ▁called ▁peri pher al ▁n erve ▁reconst ruction . ▁The ▁injured ▁n erve ▁is ▁identified ▁and ▁exposed ▁so ▁that ▁normal ▁n erve ▁t issue ▁can ▁be ▁exam ined ▁above ▁and ▁below ▁the ▁level ▁of ▁injury , ▁usually ▁with ▁magn ification , ▁using ▁either ▁l oup es ▁or ▁an ▁operating ▁mic ros cope .