N-METHYL-D-ASPARTATE (NMDA) AND NON-NMDA GLUTAMATE-RECEPTOR ANTAGONISTS PROTECT FROM APOPTOSIS INDUCED IN THE LATERAL GENICULATE-NUCLEUS OFRABBITS EXPOSED TO THE DARK

Mono or binocular deprivation, during early postnatal development, pro duces dramatic effects on the anatomy and physiology of the visual sys tem. Here we report that dark exposure induces apoptotic cell death in the lateral geniculate nucleus (LGN) of adult rabbit and this may be related to activation of N-methyl-D-aspartate (NMDA) and non-NMDA subt ypes of glutamate receptors. In situ DNA fragmentation (TUNEL) was obs erved in the LGN of rabbits exposed to dark for 48 h. Morphological ch anges were confirmed on hematoxylin-eosin stained brain tissue coronal sections. Systemic treatment with CGP 040116 or MK 801, two NMDA rece ptor antagonists, and with GYKI 52466, a non-NMDA receptor antagonist, prevented in situ DNA fragmentation and nuclear chromatin marginaliza tion and condensation. in no instance was apoptosis seen in rabbits ke pt under a normal light-dark cycle. Our findings indicate that glutama te, acting on NMDA and non-NMDA receptors, may be involved in the mech anisms of apoptotic cell death induced in the LGN of adult rabbits exp osed to darkness. (C) 1997 Elsevier Science Ireland Ltd.