Intracerebroventricular Administration of Leukocytic Endogenous Mediators (LEM) in the Rat 1

Summary

LEM obtained from glycogen-induced peritoneal exudates in rabbits were injected into the lateral cerebral ventricle of rats to determine if LEM had a primary site of action in the central nervous system. LEM injected icv in the dose of 10, 20, or 50 μl was observed to produce a rapid hy-perthermia. Injection of heated LEM failed to cause a hyperthermic response. Endo-toxin and heated endotoxin (20 ng/20 μl/ rat) administered icv each produced a delayed hyperthermia as compared to LEM. The various doses of LEM were also observed to significantly decrease plasma iron and zinc, increase plasma copper, increase the synthesis of plasma α₂ acute-phase protein (α₂-MFP), and cause a flux of a nonme-tabolizable amino acid ([¹⁴C]AIB) to the liver. These observations suggest that LEM in doses which are inactive systemically can mediate certain effects on or through the central nervous system following icv administration.

The authors wish to acknowledge the invaluable technical assistance of Ms. Beverly A. Carter and Mr. Wayne Rill. We are grateful to Drs. Philip Sobocinski and David T. George for their thoughtful discussion.