Role of the non-opioid dynorphin peptide des-Tyr-dynorphin (DYN-A(2-17)) in food intake and physical activity, and its interaction with orexin-A.

Food intake and physical activity are regulated by multiple neuropeptides, including orexin and dynorphin (DYN). Orexin-A (OXA) is one of two orexin peptides with robust roles in regulation of food intake and spontaneous physical activity (SPA). DYN collectively refers to several peptides, some of which act through opioid receptors (opioid DYN) and some whose biological effects are not mediated by opioid receptors (non-opioid DYN). While opioid DYN is known to increase food intake, the effects of non-opioid DYN peptides on food intake and SPA are unknown. Neurons that co-express and release OXA and DYN are located within the lateral hypothalamus. Limited evidence suggests that OXA and opioid DYN peptides can interact to modulate some aspects of behaviors classically related to orexin peptide function. The paraventricular hypothalamic nucleus (PVN) is a brain area where OXA and DYN peptides might interact to modulate food intake and SPA. We demonstrate that injection of des-Tyr-dynorphin (DYN-A(2-17), a non opioid DYN peptide) into the PVN increases food intake and SPA in adult mice. Co-injection of DYN-A(2-17) and OXA in the PVN further increases food intake compared to DYN-A(2-17) or OXA alone. This is the first report describing the effects of non-opioid DYN-A(2-17) on food intake and SPA, and suggests that DYN-A(2-17) interacts with OXA in the PVN to modulate food intake. Our data suggest a novel function for non-opioid DYN-A(2-17) on food intake, supporting the concept that some behavioral effects of the orexin neurons result from combined actions of the orexin and DYN peptides.

Seasonal onset of systemic-onset juvenile rheumatoid arthritis.

OBJECTIVE: This study was undertaken to investigate the recent finding of a seasonal difference in the onset of systemic-onset juvenile rheumatoid arthritis (SoJRA). We hypothesized that a seasonal onset pattern might implicate on infectious agent as a cause of SoJRA. METHODS: The date of onset was collected from the records of all patients with SoJRA from 1980 to 1992 at presentation to pediatric rheumatology clinics across Canada. The onset pattern of SoJRA was then compared with incidence data on viral infections obtained for the same period. RESULTS: Across Canada the onset of SoJRA was constant across the seasons. However, in the Prairie region there was a statistically significant seasonal pattern, with peaks in autumn and early spring. We could find no evidence that viral incidence correlated with disease incidence either throughout Canada or in the Prairie region. CONCLUSIONS: If a seasonal infectious agent causes SoJRA, then it is likely only one of several causes and may act only in certain regions. Future studies should be carried out in those areas where SoJRA does have a seasonal onset pattern.

Raynaud syndrome in childhood.

Twenty-seven patients with Raynaud syndrome (mean age at onset 11.7 years) were studied to determine the prevalence of primary Raynaud syndrome and to assess the predictive role of antinuclear antibody, nail-fold capillary microscopy, and photoelectric plethysmography in this population. Fourteen patients (52%) had a connective tissue disease, four (15%) had a probable connective tissue disease, and nine (33%) had primary Raynaud syndrome. In all patients with either a connective tissue disease or a probable connective tissue disease, there was a positive reaction to antinuclear antibody, in contrast to patients with primary Raynaud syndrome, in whom antinuclear antibody was not detected. Nail-fold capillary microscopy scores differed significantly between patients with either a connective tissue disease or a probable connective tissue disease and those with primary Raynaud syndrome for both enlarged loop score (p less than 0.025 and less than 0.05, respectively) and avascular score (p less than 0.005 and less than 0.01, respectively). Photoelectric plethysmography scores were reduced in all groups but did not differ significantly between groups. Our findings suggest that in children with Raynaud syndrome, the primary type is more common than was originally suspected, and that both antinuclear antibody and nail-fold capillary microscopy, but not photoelectric plethysmography, can distinguish patients with primary Raynaud syndrome from those with either a connective tissue disease or a probable connective tissue disease.