Differential effects of cisterna magna cannulation on beta-endorphin levels in rat plasma and cerebrospinal fluid.
The concentration of beta-endorphin-like immunoreactivity (beta-ELIR) was determined in plasma and cerebrospinal fluid (CSF) of rats at various times following the implantation under Hypnorm anesthesia of a permanent cannula into the cisterna magna. Plasma beta-ELIR levels were highly increased immediately after the operation, and gradually returned to basal within 6 h. The beta-ELIR concentration in CSF followed a completely different pattern. It appeared to be rather stable during the first hour after the operation, was decreased at 2 h, and showed a marked increase 24 h after surgery. Two days after the surgery, beta-ELIR levels in CSF had decreased to a stable basal level which was maintained for at least 7 days. When at this stage animals were treated with Hypnorm, plasma beta-ELIR was again highly increased 30 min and not 24 h after injection, but no changes were found in the beta-ELIR concentration in CSF. These data indicate that implantation of a cannula into the cisterna magna induces postoperative changes in the CSF levels of beta-endorphin that are detectable up to at least 24 h later. Moreover, the lack of correlation between CSF and plasma levels of beta-ELIR points towards differences in the regulation of brain and pituitary pro-opiomelanocortin cells.
Barna
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Rudolf Magnus Institute for Pharmacology, Medical Faculty, University of Utrecht, The Netherlands.
Sweep
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CG
Veldhuis
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HD
Wiegant
V M
VM
D000818:Animals; D002404:Catheterization; D002946:Cisterna Magna / Q000502:physiology*; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*
D001615:beta-Endorphin