An Enriched Environment Leads to Increased Synaptic Plasticity-Associated miRNA Levels after Experimental Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: In subarachnoid hemorrhage (SAH), impairments in motor and cognitive functions may occur and continue in later periods. MicroRNAs (miRNAs) are small non-coding RNAs that can directly or indirectly affect synaptic reconstruction. mir-132, mir-134, and mir-138 are the leading miRNAs that can be effective on some neurological functions through its effects on synaptic plasticity in the relevant brain areas. In our study, it was aimed to determine the levels of miRNAs in the hippocampus and frontal lobe of rats exposed to different environmental conditions after the experimental SAH. METHODS: SAH was created using the cisterna magna double blood-injection method. Brain tissues were collected at different times after the last blood injection. Rats were grouped according to the different environmental conditions in which they were kept. Expression levels of miRNAs were performed by qPCR and ultrastructural changes in samples were determined by transmission electron microscopy (TEM). RESULTS: After SAH, miR-132, miR-134, and miR-138 expressions in the frontal lobes of rats increased in impoverished environment on the 7th day and in the enriched environment on the 14th day. It was observed that the myelin and microtubule structures in the axons that were disrupted after SAH were more organized and stable in the enriched environment. CONCLUSIONS: After SAH, different environmental conditions may affect the miRNA levels associated with synaptic plasticity and microtubule organization in the frontal lobe, and this might have some effects especially on cognitive and motor functions related to this brain area.

COMPARISON OF DIFFERENT ENVIRONMENTAL CONDITIONS IN THE FOLLOW-UP OF SUBARACHNOID HEMORRHAGE: An Experimental Rat Study.

AIM: We questioned the effect of different environmental conditions on the brain in rats with subarachnoid haemorrhage. MATERIAL AND METHODS: Microtubules in neurons mediate both the consciousness and memory and regulate firing. Microtubule-associated proteins (MAPs) promote microtubule organisation and dynamics. We investigated MAP2, tau and amyloid beta levels in the hippocampus and the frontal cortex after experimental subarachnoid haemorrhage in rats. Subjects were divided into subgroups and were housed either in an enriched, standard or isolated environment. Tissue levels were measured on day 7 for short-term outcomes and on day 14 for long-term outcomes after SAH. RESULTS: After SAH, the results showed that decreased MAP2 levels, a trend in pathologic tau accumulation and increased amyloid beta levels in different brain regions of rats kept in an isolated environment. Frontal lobe MAP2 levels were increased in rats kept in an enriched environment for 7 days. Pathological hippocampal tau and frontal lobe amyloid beta levels were increased in rats kept in an isolated environment for 7 days. Increased MAP2 levels in the hippocampus, decreased frontal and hippocampal amyloid beta were seen in rats kept in an enriched environment for 14 days. CONCLUSION: Although it would be too early to offer recommendations, results of the present study support that an enriched environment may be more valuable in the follow-up of SAH. Further experimental studies would provide more reliable results to facilitate discussions about how to optimise the patient\'s environmental conditions.