Diabetes, Vol 44, Issue 1 25-30, Copyright © 1995 by American Diabetes Association
Reduced levels of mRNA encoding endoskeletal and growth-associated proteins in sensory ganglia in experimental diabetes
L Mohiuddin, P Fernyhough and DR Tomlinson
Department of Pharmacology, Queen Mary and Westfield College, London, UK.
This study investigated changes in levels of mRNAs encoding the three
neurofilament (NF) proteins NF-L (low), NF-M (medium), and NF-H (high) and
two growth-associated proteins, GAP-43 and T alpha 1 alpha-tubulin, in
lumbar dorsal root ganglia of control and streptozocin-induced diabetic
rats. After 8 weeks of diabetes the animals were killed, and total RNA was
isolated from the L4 and L5 dorsal root ganglia and subjected to Northern
blotting, with constant amounts of total RNA loaded onto each lane. A
truncated sense RNA for GAP-43 was included as an internal standard during
RNA isolation to enable accurate quantification of mRNA levels. The filters
were probed sequentially with 32P-labeled cDNAs encoding NF-L, NF-M, NF-H,
GAP-43, T alpha 1 alpha-tubulin, and citrate synthase. Hybridizing RNAs
were detected by autoradiography and quantified by image analysis.
Hybridization signals were normalized to those of the internal standard. In
diabetes, NF-L mRNA levels (2.5- and 4-kilobase [kb] transcripts) were
decreased by 35 (P = 0.002) and 34% (P < 0.001), respectively, the NF-H
mRNA level was decreased by 65% (P < 0.001), but the NF-M mRNA remained
unchanged. T alpha 1 alpha-tubulin and GAP-43 mRNA levels were reduced by
56 (P < 0.001) and 30% (P < 0.05), respectively. Levels of citrate
synthase mRNA were unchanged. These data indicate a selective defect of
expression of growth-associated and endoskeletal proteins in experimentally
induced diabetes.