My work at Brown contributed to the demonstration that N-acyl-dopamines are present in the mammalian brain and that N-oleoyldopamine (OLDA) and N-arachidonoyldopamine (NADA) may function as endovanilloids involved in pain modulation through activation of the vanilloid type 1 receptor (VR1) in the periphery and/or the brain. However, little is know about the mechanisms of N-acyl-dopamine synthesis and activity in the central and peripheral nervous system. To better understand the role of these N-acyl-dopamines as signaling molecules for the modulation and transduction of pain, a variety of in vivo and in vitro studies are proposed. The first set of experiments will determine whether the VR1 receptor is localized in brainstem pain control systems. Although there is substantial evidence for VR1 in the brain, the methods used may have detected VR1 subtypes instead of or in addition to VRI. Therefore, the mass western technique, which allows precise identification of membrane proteins with isotope-coded affinity tags and nanoLC/tandem mass spectrometry will be used to search for VR1 in the pariaqueductal gray and the rostral ventromedial medulla, two major sites of pain modulation. The dorsal root ganglion (DRG) will be used as a positive control. A second set of experiments will be conducted to examine the effects of N-acyldopamines in the pariaqueductal gray (PAG) and rostral ventromedial medulla (RVM). Recent studies show an antinociceptive effect of capsaicin administration into the PAG. This suggests a modulatory role for endovanilloids in descending pain control systems. To study this role, N-acyl-dopamines will be injected into the PAG Or RVM and two types of experiments will be performed: a) the rat hind paw will be inflamed using Complete Freund's Adjuvant and withdrawal latency from a radiant heat source will be examined, and b) extracellular recording from the superficial lamina of the dorsal horn will be conducted to characterize the effects of N-acyl-dopamines in descending pain control structures on spontaneous cell firing and cell firing in response to a noxious thermal stimulus. The third set of experiments identifies changes in the levels of N-acyl-dopamines in response to nociception. Cell lysis, solid phase extraction, and mass spectrometric analysis will be used to determine whether structures involved in pain sensation and modulation including the paw skin, DRG, PAG, and RVM increase or decrease their levels of N-acyl-dopamines in response to inflammation in the rat hind paw induced by Complete Freud's Adjuvant.
| De Petrocellis, Luciano; Chu, Constance J; Moriello, Aniello Schiano et al. (2004) Actions of two naturally occurring saturated N-acyldopamines on transient receptor potential vanilloid 1 (TRPV1) channels. Br J Pharmacol 143:251-6 |
