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Updated: Aug 5, 2026
Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections
Published on: November 14, 2016
Preproinsulin I and II mRNAs and insulin electron microscopic immunoreaction are present within the rat fetal nervous
R Schechter1, D Beju, T Gaffney
1William K. Warren Medical Research Institute, University of Oklahoma Health Sciences Center, Tulsa 74136-7862, USA.
Abstract:
Insulin-like substance has been found within the nervous system. In the rat, preproinsulin II mRNA was shown within the brain and preproinsulin I mRNA within the retina. The present study demonstrates the presence of preproinsulin mRNAs within the 15, 17 and 19 day gestational age fetal rat brain, spinal cord and dorsal root ganglia (DRG), employing RNA template-specific polymerase chain reaction (RS-PCR), semi-nested PCR and RNase protection assay. Preproinsulin I mRNA was present in the 17 and 19 day gestational age brain, spinal cord and DRG, and only in the brain of the 15 day gestational age brain. Preproinsulin II mRNA was present in all the gestational ages studied in the brain, spinal cord and DRG. The RS-PCR and the semi-nested PCR demonstrated products that co-migrated with the pancreatic control. The semi-nested products were characterized as preproinsulin I and II by restriction enzyme digestion and sequence. RNase protection assay using specific cRNA for preproinsulin I and II showed a band that co-migrated with pancreatic preproinsulin I and II mRNAs, and confirmed the PCR results. In addition, insulin receptor mRNA was detected by RS-PCR. Ultrastructural studies showed insulin immunoreaction within the endoplasmic reticulum, Golgi apparatus, cytoplasm, axon, dendrites, and in relation to the synapses. Thus, we demonstrated the presence of preproinsulin I and II mRNA, insulin receptor mRNA and insulin immunoreaction within the rat fetal central and peripheral nervous system.
Insights
This study found insulin gene expression (preproinsulin I and II mRNA) in the developing rat nervous system, including the brain and spinal cord. Insulin signaling components were also detected, suggesting a role for insulin in neural development.
Area of Science:
- Neuroscience
- Molecular Biology
- Developmental Biology
Background:
- Insulin-like substances have been identified in the nervous system.
- Previous studies detected preproinsulin II mRNA in the rat brain and preproinsulin I mRNA in the retina.
Purpose of the Study:
- To investigate the presence and localization of preproinsulin I and II mRNAs and insulin receptor mRNA in the fetal rat nervous system.
- To confirm the identity of these mRNAs and visualize insulin immunoreaction within neural cells.
Main Methods:
- RNA template-specific polymerase chain reaction (RS-PCR) and semi-nested PCR were used to detect preproinsulin and insulin receptor mRNAs.
- RNase protection assay was employed for confirmation.
- Ultrastructural analysis was performed to identify insulin immunoreaction.
Main Results:
- Preproinsulin I and II mRNAs were detected in the fetal rat brain, spinal cord, and dorsal root ganglia (DRG) across different gestational ages.
- Insulin receptor mRNA was also identified.
- Ultrastructural studies revealed insulin immunoreaction in various neuronal compartments, including synapses.
Conclusions:
- The study demonstrates the presence of preproinsulin I and II mRNA, insulin receptor mRNA, and insulin immunoreaction in the rat fetal central and peripheral nervous systems.
- These findings suggest an intrinsic insulin system within the developing nervous system.
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