Provided is a means of contributing to the elucidation of the mechanism for post-zoster neuralgia, and promoting the regeneration of damaged nerves. Also provided is a means that is effective, with decreased adverse reactions, in preventing or treating disorders due to nerve cell death accompanying post-zoster neuralgia, chronic pains, postherpetic neuralgia, cerebral stroke, degenerative diseases and the like, and the aforementioned diseases. An agent for promoting neurite elongation comprising as an active ingredient an antibody that recognizes a varicella-zoster virus immediate-early protein and cross-reacts with a brain-derived neurotrophic factor； a prophylactic or therapeutic agent for a nervous disease, comprising as an active ingredient the aforementioned antibody； an agent for inhibiting neurite elongation comprising as an active ingredient an antibody that recognizes a varicella-zoster virus immediate-early protein and inhibits a brain-derived neurotrophic factor； and a prophylactic or therapeutic agent for a disease with nerve hypersensitivity caused by a condition selected from the group consisting of postherpetic neuralgia, chronic pains, experience-dependent social aversion and stress, comprising as an active ingredient the aforementioned inhibitory antibody.
