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Acute Hemorrhagic Stress in Conscious Sheep Elevates Immunoreactive β -Endorphin in Plasma but Not in Cerebrospinal Fluid*

1986; Oxford University Press; Volume: 118; Issue: 6 Linguagem: Inglês

10.1210/endo-118-6-2572

1945-7170

Roger Smith, Philip Owens, Margaret Lovelock, E.-C. Chan, John Falconer,

Pain Mechanisms and Treatments

The effects of acute hemorrhagic stress on the concentrations of immunoreactive β-endorphin (IR βEP) in cerebrospinal fluid (CSF) and blood plasma were investigated in conscious sheep in which the cisterna magna, a carotid artery, and a jugular vein were chronically cannulated. Serial samples of CSF and jugular venous blood were collected before and after acute arterial hemorrhage and in control experiments. Basal concentrations of IR βEP were higher in plasma than in CSF. Plasma concentrations of cortisol and IR βEP increased within 45 min of the commencement of hemorrhage and returned to near baseline levels within 2.25 h. The concentrations of cortisol and IR βEP in plasma observed after hemorrhage were significantly different from those observed in controls (analysis of variance). Neither the molar nor the relative changes from initial concentrations of IR βEP in CSF were significantly different between hemorrhage-stressed and controls by analysis of variance. These results show that hemorrhagic stress in conscious sheep elevates concentrations of IR βEP in plasma but not in CSF, indicating that pituitary βEP secreted into blood does not enter CSF in significant amounts. (Endocrinology118: 2572–2576, 1986)