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Increases in transforming growth factor-beta mRNA in hippocampus during response to entorhinal cortex lesions in
N R Nichols1, N J Laping, J R Day
1Ethel Percy Andrus Gerontology Center, Los Angeles, CA.
Abstract:
Transforming growth factor-beta mRNA was detected with a rat TGF-beta 1 coding sequence probe as a 2.5 kb band by RNA blot hybridization of total RNA from the adult male rat hippocampus. Following electrolytic lesions of the entorhinal cortex that cause hippocampal deafferentation and synaptic remodeling, TGF-beta mRNA increases 5-fold in ipsilateral hippocampus when compared with intact controls. This increase was independent of prior adrenalectomy or corticosterone-replacement. These data demonstrate that TGF-beta gene expression increases in response to hippocampal deafferentation.
Insights
Transforming growth factor-beta (TGF-beta) mRNA expression significantly increases in the adult male rat hippocampus after entorhinal cortex lesions. This gene expression change is linked to deafferentation and synaptic remodeling, not adrenal hormones.
Area of Science:
- Neuroscience
- Molecular Biology
- Gene Expression
Background:
- Transforming growth factor-beta (TGF-beta) is a cytokine involved in cellular processes.
- Hippocampal deafferentation, caused by entorhinal cortex lesions, leads to synaptic remodeling.
- The role of TGF-beta in response to such structural brain changes is not fully understood.
Purpose of the Study:
- To investigate the changes in TGF-beta mRNA expression in the adult male rat hippocampus following entorhinal cortex lesions.
- To determine if TGF-beta gene expression is altered due to hippocampal deafferentation and synaptic remodeling.
Main Methods:
- RNA blot hybridization was used to detect TGF-beta 1 mRNA in total RNA from adult male rat hippocampi.
- Electrolytic lesions of the entorhinal cortex were performed to induce hippocampal deafferentation.
- TGF-beta mRNA levels were compared between lesioned and intact control rats.
Main Results:
- A 2.5 kb band for TGF-beta mRNA was detected in the adult male rat hippocampus.
- Following entorhinal cortex lesions, TGF-beta mRNA levels increased 5-fold in the ipsilateral hippocampus compared to controls.
- This TGF-beta mRNA increase was observed irrespective of prior adrenalectomy or corticosterone replacement.
Conclusions:
- Hippocampal deafferentation and associated synaptic remodeling robustly upregulate TGF-beta gene expression.
- TGF-beta is implicated in the cellular response to neuronal injury and structural reorganization in the hippocampus.
- The observed increase in TGF-beta mRNA is an intrinsic response to deafferentation, independent of the adrenal axis.