methods of activating a signaling cascade comprising , introducing leptin and / or a cytokine to a receptor complex comprising gp 130 , optionally in combination with a compound acting on adenylate cyclase or acting on one or more downstream targets of adenylate cyclase , thereby inducing genes in neuro - endocrine cells or cells of neuro - endocrine origin . two distinct gene - sets are induced , immediate early response genes , and late induced target genes . strong co - stimulation with the adenylate cyclase activator forskolin was shown with respect to late induced target genes . transcripts encoding leptin induced protein i and leptin induced protein ii were identified ; however , no forskolin co - stimulatory effect was observed . it is also demonstrated that leptin modulates in vivo expression of mt - ii , fnk and pancreatitis associated protein i genes .