A clinical study has recently suggested that perinatal stress increasesα-melanocyte-stimulating hormone (α-MSH) secretion of human pituitary intermediate lobe, but the activity declines shortly after birth(Mauri et al. 1993 J Clin Endocrinol Metab 77:113). It is known that perinatal α-MSH infusions may cause neurobehavioral alterations and changes in pain reactivity. The aim of the present study was to determine the concentration of α-MSH during asphyxia and recovery of piglets with pneumothorax, using a specific radioimmunoassay, in plasma taken from the internal jugular vein and in cerebrospinal fluid (CSF) taken from cisterna magna. Fifteen asphyxiated newborn pigs (4-9 h; 1,180-1, 600 g) were included in the present experiment. After general (ketamine, 10 mg×kg-1) and local (lidocain, 1.0 mL, 1.0 vol%) anesthesia bilateral pneumothorax was induced in each pigs, and cardiovascular and metabolic failure with bradyarrhythmia, severe arterial hypotension and combined acidosis developed 48 ± 2 min (all values presented are means ± SEM) after the beginning of the experiments. Then the animals were reanimated and a recovery stage with moderate tachycardia, arterial hypotension and metabolic acidosis were observed. Blood and CSF samples were taken 4 times: at the beginning, at critical asphyxia, as well as 10 and 180 min after resuscitation. The values were compared using Friedman repeated measure ANOVA on ranks followed by the Student-Newman-Keuls test; significance: P<0.05 compared toa baseline, basphyxia, c10-min recovery values. We conclude that asphyxia and reperfusion resulted in an increase in plasmaα-MSH concentration, while the CSF hormone levels decreased in newborn pigs. Table

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