Galanin peptides
extracellular space
Concomitant evaluation of plasma galanin and catecholamine levels during a cold pressor test in healthy human male and female subjects.
The neuropeptide galanin (GAL) is localized in the peripheral and central nervous systems as well as in the adrenal medulla where it coexists with catecholamines. We evaluated the changes in GAL plasma levels as well as systolic and diastolic blood pressures and in the plasma levels of epinephrine and norepinephrine (NE) in normal human male and regularly menstruating female subjects during the activation of the sympathoadrenal system by a cold pressor test. The test was performed by immersing the hand of the subject in 1 degree C cold water for 4 min. Blood samples were collected both under basal conditions and at subsequent intervals during the cold stimulus as well as at the end of the recovery phase. The values were compared with those obtained when the same subjects were sham tested. As expected, systolic and diastolic blood pressures increased in both sexes during the cold test; the systolic blood pressure values were significantly (p < 0.05) higher in males. Epinephrine and NE levels rose significantly above baseline in both male and female subjects after the cold stimulus; the NE increments were significantly (p < 0.05) higher in males. The basal GAL levels were found to be variable but not sexually dimorphic. In both sexes, during cold stimulus and recovery phase, GAL values were found to be not significantly different from those detected during the sham test. These results demonstrate that the release of GAL in peripheral blood is not associated with that of catecholamines in response to the cold pressor test.