Ultrastructural Changes, Nuclear Factor-κB Activation, and Tumor Necrosis Factor-α Expression in Brain after Acute Normovolemic Hemodilution and Controlled Hypotension in Rats

Cilj Ispitati moždana oštećenja u štakora nakon različitih stupnjeva akutne normovolemične hemodilucije i kontrolirane hipotenzije s pomoću morfološke analize neurona i provjeriti aktivaciju jezgrenog faktora-κB (NF- κB) i izražaj čimbenika nekroze tumora-α (TNF-α). Postupci Četrdeset štakora nasumično je raspoređeno u one lažno operirane i one s normovolemičnom hemodilucijom i kontroliranom hipotenzijom (s hematokritom od 30%, 25%, 20%, and 15%). Normovolemična hemodilucija i kontrolirana hipotenzija izazvane su nakon što su osnovni fiziološki parametri praćeni 20 minuta. Kontrolirana hipotenzija izazvana je nakon 30 minuta s pomoću natrijeva nitroprusida, a srednji arterijski tlak održavao se sljedeći sat vremena na 50-60 mmHg. Tri i pol sata nakon operacije životinje su eutanazirane. Razina TNF-α i aktivnost NF-κB određene su u temporalnoj moždanoj kori. Ultrastrukturna oštećenja ocijenjena su u području CA1 u hipokampusu. Promjene mitohondrija ocijenjene su polukvantitativno. Rezultati U skupinama s hematokritom od 20% i 15% nađena su izražena ultrastrukturna oštećenja, poput denaturacije mitohondrija i izobličenja jezgara. Izražaj TNF-α i aktivnost NF-κB bila je značajno povišena u svim skupinama s normovolemičnom hemodilucijom i kontroliranom hipotenzijom, a najviše su bile u skupini s hematokritom od 25%. Zaključak Izražena normovolemična hemodilucija i kontrolirana hipotenzija s hematokritom ≤20% mogu izazvati moždana oštećenja pa ih treba izbjegavati. U stanju ishemije, aktivacija NF-κB i izražaj TNF-α mogu predstavljati funkcionalne korelate. Bolje upoznavanje uloge NF-κB i TNF-α u mozgu može otvoriti nove pristupe prevenciji i liječenju neuroloških bolesti.Aim To examine brain damage following different degrees of acute normovolemic hemodilution combined with controlled hypotension (ANH-CH) by neuronal morphological analysis and investigate the expression of nuclear factor-kappa B (NF-κB) activity and tumor necrosis factor-alpha (TNF-α) in the rat. Methods Forty rats were randomly assigned to receive a sham operation or ANH-CH (with hematocrit 30%, 25%, 20%, and 15%). ANH was performed after baseline physiological parameters had been monitored for 20 minutes. CH was induced 30 minutes later using sodium nitroprusside and mean arterial pressure was maintained at 50-60 mm Hg for 1 hour. Rats were euthanatized 3 and a half hours after operation. TNF-α levels and NF-κB activities in cerebral temporal cortex were measured. Ultrastructural alterations in the CA1 region of the rat hippocampi were observed. Changes in mitochondria were evaluated semiquantitatively. Results Marked ultrastructural alterations, such as mitochondrial denaturalization and nucleus distortion, were observed in the CA1 region of the hippocampus in the ANH-CH hematocrit 20% group and ANH-CH hematocrit 15% group. TNF-α expression and NF-κB activity in the cerebral temporal cortex significantly increased in all ANHCH groups and peaked in the ANH-CH hematocrit 25% group. Conclusion Severe ANH-CH with hematocrit ≤20% may induce cerebral damage and should be avoided. NF-κB activation and TNF-α expression may play a functional role under the ischemic condition. A better understanding of the role of NF-κB and TNF-α in the brain may lead to a novel approach for preventing and treating various neurological disorders