Analysis of brain neuropeptides by capillary electrophoresis: determination of luteinizing hormone-releasing hormone from ovine hypothalamus.

The use of capillary electrophoresis to analyze in vivo release of luteinizing hormone-releasing hormone from the ewe median eminence and tissue content of luteinizing hormone-releasing hormone from discrete brain areas (within and immediately adjacent to the median eminence) is described. Results were compared with those obtained with a specific luteinizing hormone-releasing hormone radioimmunoassay. In vivo release samples were obtained by a push-pull cannula procedure. The exact position of the median eminence in each animal was determined from lateral roentgenographs after infusion of a radiopaque dye into the third ventricle. Each ewe median eminence was perfused with an artificial cerebrospinal fluid solution and sampled at 20-min intervals. Brain tissues for luteinizing hormone-releasing hormone content were obtained after each animal was killed. Samples were either analyzed by capillary electrophoresis and UV detection at 210 nm or assayed with a specific luteinizing hormone-releasing hormone radioimmunoassay. Tissue homogenate content and release samples had several peaks resolved by capillary electrophoresis and UV detection. Luteinizing hormone-releasing hormone was identified as one of these peaks. Luteinizing hormone-releasing hormone was also shown to be present in these samples when evaluated by radioimmunoassay. A good correlation between capillary electrophoresis and radioimmunoassay was observed for luteinizing hormone-releasing hormone content values obtained from discrete hypothalamic areas.(ABSTRACT TRUNCATED AT 250 WORDS)