Identification of brain target neurons using a fluorescent conjugate of corticotropin-releasing factor.

Corticotropin-releasing factor (CRF) is a peptide well known for its role in coordinating various neuroendocrine, autonomic, and behavioral components of the vertebrate stress response, including rapid enhancement of locomotor activity. Although CRF's locomotor enhancing properties are well documented, the neuronal mechanisms and specific target neurons that underlie the peptide's effect on locomotor behavior remain poorly understood. In the present study, we describe the synthesis and functional characteristics of a CRF rhodamine analogue TAMRA-X conjugate mixture (CRF-TAMRA 1), to be used for tracking this peptide's internalization into target neurons in the brainstem of an amphibian, the roughskin newt (Taricha granulosa).