Klepper S, Naftolin F, Piepmeier JM. Verapamil treatment attenuates immunoreactive GFAP at cerebral cortical lesion site.
Brain Res 1995;
695:245-9. [PMID:
8556338 DOI:
10.1016/0006-8993(95)00825-b]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cerebral cortical lesions were produced using a stereotactic injection system in Sprague-Dawley rats randomly assigned to three groups: (1) needle lesioned and uninjected (Lesioned), (2) needle lesion and simultaneous local injection of 50 or 100 microliters 0.9% saline (L/Saline), and (3) needle lesion and simultaneous local injection of 50 or 100 microliters Verapamil-HCl (VHCL) (2.5 mg/ml (5 mM) Abbott Labs, Chicago, IL), a passive, L-type calcium channel blocker (L/VHCL). The lesioning induced expression of glial fibrillary acidic protein (GFAP), a type of intermediate filament protein expressed in reactive astrocytes, at the lesion site. There was a reduction in GFAP-like immunoreactivity (GFAP-IR) in the L/VHCL group versus the Lesioned and the L/Saline groups. There was a five-fold increase of GFAP-IR at 24 h post lesion in the L/Saline group, but no statistically significant increase seen in the Lesioned or L/VHCL groups at either volume. Pretreatment of the anti-GFAP with VHCL did not impair the antigen labeling. To determine whether differences in pHs, or volume could account for these findings, a second experiment was performed using pH-matched saline or VHCL in 10 microliters volume injected into contralateral hemispheres at the time of lesioning. There was an 80% reduction in GFAP-IR in the L/VHCL group at 72 h compared with the L/Saline group. These data suggest that VHCL may suppress the early increase of GFAP-IR in response to cortical lesion and that reducing transmembrane calcium flux through L-type calcium channels may be the mechanism involved.
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