Neurogenically mediated leakage of plasma protein occurs from blood vessels in dura mater but not brain.
Utilizing 125I-BSA administered intravenously, a simple, reliable, and sensitive method was established for the detection of plasma protein extravasation in the dura of rats and guinea pigs following chemical, electrical, or immunological stimulation. Extravasated 125I-BSA or Evans blue was noted in the dura and conjunctiva but not in the temporalis muscle of saline-perfused rats following intravenous capsaicin, 1 mumol/kg. Capsaicin-induced extravasation was mediated by unmyelinated and small myelinated fibers since leakage did not develop in adult animals in whom these fibers were destroyed by capsaicin pretreatment (50 mg/kg) as neonates. An ipsilateral increase in Evans blue and 125I-BSA was found in the dura, eyelids, lips and gingival mucosa, and snout following electrical stimulation of the rat trigeminal ganglion. This increase was also C-fiber dependent. Among those peptides contained in perivascular afferent fibers and administered intravenously, substance P (SP) and neurokinin A (NKA), but not calcitonin gene-related peptide, caused a dose-dependent extravasation in the dura and conjunctiva of rats. Neonatal capsaicin pretreatment did not attenuate SP- nor NKA-induced effects in the dura and actually increased extravasation in the conjunctiva. Intravenous administration of 5-HT or bradykinin to normal adult rats or adult rats pretreated as neonates with capsaicin increased levels of 125I-BSA in both the dura and the conjunctiva. Histamine and prostaglandin E2, on the other hand, caused protein leakage in the conjunctiva but not in the dura of rats; however, histamine did induce extravasation in the dura of guinea pigs.(ABSTRACT TRUNCATED AT 250 WORDS)
Stroke Research Laboratory, Massachusetts General Hospital, Boston 02114.
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S
Markowitz
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Saito
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Moskowitz
D000818:Animals; D001798:Blood Proteins; D001921:Brain / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology*; D002211:Capsaicin / Q000494:pharmacology; D004388:Dura Mater / Q000098:blood supply / Q000187:drug effects / Q000503:physiopathology*; D004558:Electric Stimulation; D006168:Guinea Pigs; D006261:Headache / Q000503:physiopathology; D007249:Inflammation / Q000503:physiopathology; D007457:Iodine Radioisotopes; D009413:Nerve Fibers, Myelinated / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains
D001798:Blood Proteins; D007457:Iodine Radioisotopes; D002211:Capsaicin