Expression of growth-associated protein Gap-43 and synaptophysin P38 mRNA in rat ischemic penumbra region after earlier rehabilitative training

Shoubiao WANG

ABSTRACT

BACKGROUND:

Recent researches have shown that mature survival brain has been proved possessing regenerative plasticity, namely structural and functional rebuilding. In mature CNS, Gap-43 level can be used as an important index for axonal impairment and regenerative reaction during brain ischemia. Moreover neural functional recovery is proved closely connected with brain plasticity after ischemic stroke.

OBJECTIVE:

To investigate the influence of earlier rehabilitative training on the expression of neural plasticity related with growth-associated protein Gap-43 and synaptophysin P38 mRNA in ischemic penumbra region of rat.

DESIGN:

Randomized controlled study.

SETTING:

Anatomical Department of Affiliated Hospital of Qingdao University.MATERIALS This study was conducted at Anatomical Laboratory of Affiliated Hospital of Qingdao University from December 1999 to June 2002. Totally 52 healthy female Wistar rats were randomly divided into sham operation group of 4 rats, rehabilitative training group of 24 rats and nature recovery group of 24 rats.

METHODS:

Thread bolt methods was used to establish Cerebral Middle Artery IR model on rats in rehabilitative group and nature recovery group by inserting an 4-0 nylon thread from external carotid artery, while rats in sham operation group received the same treatment without thread insertion. The experimental models were believed successfully established,if rat displayed left Homer's sign with right forearm flexed and abducted when lifting it up by tails after awakened. Specimen were collected at postoperative 24 hours in sham operative group; while rats in rehabilitative training group received rehabilitative training in MG labyrinth after CMA blocked for 120 minutes and reperfusion for 6 hours, twice a day for 10-20 minutes each time, in avoid of fatigue. Specimen were collected at postoperative 6 hours, 1, 3, 7, 14, 21 days in operative group;specimen were collected at occlusion 120 minutes reperfusion 6 hours, 1,3, 7, 14, 21 days in nature recovery group which was used as control of nature course of disease. They were made into wax slices and underwent Nissl's staining, meanwhile VIDAS 21 microscopic image analysis system was used to detect the products absorbency in ischemic penumbra region (value A), unimpaired callus value A in the same slice was considered as background value, therefore adjusted value A could be obtained by removing background value A. The immuneactivity at ischemic center were not quantitatively analyzed.of growth-associated protein Gap-43 and synaptophysin P38 mRNA at observations at ischemic penumbra region in rehabilitative training group.

RESULTS:

Totally 52 rats were enrolled in this study and all data sociated protein Gap-43 and synaptophysin P38 mRNA at ischemic penumbra region at various IR time points Cortical region was lightly stained in sham operation group, and the adjusted value A of Gap-43 and P38 mRNA were 0.37±0.12 and 0.70±0.14 respectively; while the Gap-43 and P38 mRNA expression began increase at postoperative 6 hours and 3 days, reaching to the peak level at 7 days and then gradually descended from onset of 14 days in nature recovery group. The expression of Gap-43 and P38 mRNA in rehabilitative training group were found higher than the corresponding nature recovery group at IR 6 hours, 1, 3, 7, 14 and 21 days, but the difference was proved signifiCell morphological observations in rehabilitative training group Under low-power microscope, we can observed necrotic nerve cells in ischemic center, with the number of nerve cell decreased and neurons displayed ischemic denaturalization shrunk cell seemed like triangle, fan and strip with nuclei deeply colored, the nucleolus was unclear and cytoplasm displayed vacuole denaturalization. Cortical neuronal cytoplasm was loose with nuclei slightly metamorphosed and deep colored. Denatured neurons were co-existed with normal neurons. There was great deal of collagenocyte that appeared in ischemic center and penumbra region at postoperative 14 days.

CONCLUSION:

The expression of Gap-43 and P38 mRNA related to neural plasticity becomes active in post IR penumbra region. Since earlier rehabilitative training can stimulate synaptogenesis from Gap-43 and P38 mRNA neurons, thereby improving the brain plasticity and postischemic limb functional recovery.