GDNF and somatostatin in sensory neurones.

Somatostatin (SOM) is a regulatory peptide produced throughout the central nervous system and in most major peripheral organs. In humans, the SOM stable analogue octreotide (OCT) is used to treat opioid-resistant pain. In animal models, SOM and OCT are analgesics and SOM released from the peripheral endings of sensory neurones exerts anti-inflammatory actions. The expression of SOM in sensory neurones can be modulated by the trophic factor glial-cell-line-derived neurotrophic factor (GDNF). Recent data show that GDNF modulates activity-induced release of endogenous SOM from both central and peripheral terminals of adult sensory neurones. This novel mechanism deserves exploration as a potential new therapeutic strategy to control two major features of inflammation: pain and leukocyte recruitment.