Novel approaches to studying activity-dependent regulation of neurotrophins and neuropeptides in sensory pathways from orofacial tissues

Growth factors are critical for normal development of craniofacial innervation. Recent evidence indicates that neuronal growth factors, and particularly members of the neurotrophin family, are also involved in activity-dependent synaptic plasticity, with wide-ranging implications for chronic orofacial pain syndromes. The authors' laboratory has developed novel approaches to studying regulation of neurotrophin expression and release from neurons by activity. This chapter presents their advances in preparation of neuron-enriched cultures of trigeminal ganglia followed by stimulation with physiological patterns of electrical activity alone, and in combination with neuropeptides and inflammatory mediators. It also describes the authors' modified, ultra-sensitive ELISA methods (ELISA in situ and 'rapid capture' ELISA) for detection of endogenous neurotrophic factors, and other neuropeptides that are expressed and released in quantities below the detectability thresholds of standard assays. These methodologies are presented using Brain-Derived Neurotrophic Factor (BDNF) and Endomorphin-2 as examples.