Dexamethasone preventing contractile and cytoskeletal protein changes in the rabbit basilar artery after subarachnoid hemorrhage.
OBJECTIVE
The aim of this project was to study the perturbations of four smooth-muscle proteins and an extracellular protein, type I collagen, after subarachnoid hemorrhage (SAH) and to examine the possible preventive effects of dexamethasone.


METHODS
Using a one-hemorrhage rabbit model, the authors first examined the effects of SAH on the expression of alpha-actin, h-caldesmon, vimentin, smoothelin-B, and type I collagen; second, they studied whether post-SAH systemic administration of dexamethasone (three daily injections) corrected the induced alterations. Measurements were obtained at Day 7 post-SAH. The proteins were studied by performing immunohistochemical staining and using a laser-scanning confocal microscope. Compared with control (sham-injured) arteries, the density of the media of arteries subjected to SAH was reduced for alpha-actin (-11%, p = 0.01) and h-caldesmon (-15%, p = 0.06) but increased for vimentin (+15%, p = 0.04) and smoothelin-B (+53%, p = 0.04). Among animals in which SAH was induced, arteries in those treated with dexamethasone demonstrated higher values of density for alpha-actin (+13%, p = 0.05) and h-caldesmon (+20%, p = 0.01), lower values for vimentin (-55%, p = 0.05), and nonsignificantly different values for smoothelin-B. The density of type I collagen in the adventitia decreased significantly after SAH (-45%, p = 0.01), but dexamethasone treatment had no effect on this decrease.


CONCLUSIONS
The SAH-induced alterations in the density of three of four smooth-muscle proteins were prevented by dexamethasone treatment; two of these proteins--alpha-actin and h-caldesmon--are directly related to contraction. This drug may potentially be useful to prevent certain morphological and functional changes in cerebral arteries after SAH.
Gomis
Philippe
P
Laboratoire de Recherches Cérébrovasculaires Centre National de la Recherche Scientifique, Unité Propre de Recherche 646 Paris, France. pgomis@chu-reims.fr
Tran-Dinh
Yves Roger
YR
Sercombe
Christine
C
Sercombe
Richard
R
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001488:Basilar Artery / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D024042:Collagen Type I / Q000096:biosynthesis; D003907:Dexamethasone / Q000494:pharmacology*; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D009124:Muscle Proteins / Q000096:biosynthesis*; D011817:Rabbits; D013345:Subarachnoid Hemorrhage / Q000150:complications* / Q000662:veterinary
D000893:Anti-Inflammatory Agents; D024042:Collagen Type I; D009124:Muscle Proteins; D003907:Dexamethasone