Late stimulation of the sphenopalatine-ganglion in ischemic rats: improvement in N-acetyl-aspartate levels and diffusion weighted imaging characteristics as seen by MR.
OBJECTIVE
To assess, by MR spectroscopy (MRS) and diffusion weighted imaging (DWI), the ability of electrical stimulation of the sphenopalatine ganglion (SPG) to augment stroke recovery in transient middle cerebral artery occluded (t-MCAO) rats, when treatment is started 18 +/- 2 h post-occlusion.


METHODS
(1)H-MRS imaging ((1)H-MRSI) and DWI were used to evaluate ischemic brain tissue after SPG stimulation in rats subjected to 2 h of t-MCAO. Rats were examined by (1)H-MRSI, DWI, and behavioral tests at 16 +/- 2 h, 8 days, and 28 days post-MCAO.


RESULTS
N-Acetyl-aspartate (NAA) levels of the stimulated and control rats were the same 16 +/- 2 h post-MCAO (0.52 +/- 0.03, 0.54 +/- 0.03). At 28 days post-occlusion, NAA levels were significantly higher in the treated group (0.60 +/- 0.04) compared with those of the untreated animals (0.50 +/- 0.04; P < 0.05). This effect was more pronounced for regions with low NAA values (0.16 +/- 0.03) that changed to 0.32 +/- 0.03 (P = 0.04) for the treated group and to 0.10 +/- 0.03 (P = 0.20) for the controls. DWI data showed better ischemic tissue condition for the treated rats, but the measured parameters showed only a trend of improvement. The MR results were corroborated by behavioral examinations.


CONCLUSIONS
Our findings suggest that SPG stimulation may ameliorate MR tissue characteristics following t-MCAO even if treatment is started 18 h post-occlusion.
School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Amnon
A
Bar-Shir
Noam
N
Shemesh
Revital
R
Nossin-Manor
Yoram
Y
Cohen
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004599:Electric Stimulation Therapy; D004566:Electrodes; D005724:Ganglia / Q000473:pathology*; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D001224:Aspartic Acid; C000179:N-acetylaspartate