Retinal ganglion cell loss after the period of naturally occurring cell death in bcl-2(-/-) mice

OVER-EXPRESSION of Bcl-2 is known to reduce the extent of retinal ganglion cell death during development as well as after axotomy. Here we investigate d whether retinal ganglion cell (RGC) numbers are reduced in mice with a ta rgeted inactivation of the bcl-2 gene. Compared with wild-type mice, adult bcl-2 null mutants have lost 29% of the retinal ganglion cell axons in the optic nerve. This reduction was almost fully established at P15, but not pr esent at P10, which marks the end of the period of naturally occurring cell death. These observations, together with the previously reported late loss of primary motoneurons and peripheral neurons, point to a general physiolo gical. requirement for Bcl-2 soon after the period of naturally occurring c ell death. NeuroReport 10:1091-1095 (C) 1999 Lippincott Williams & Wilkins.