We have gathered information suggesting that the spinal cord (SC) is a glucocorticoid (GC) responsive tissue. The SC contains receptors (R) for both GC and mineralocorticoids and concentrate adrenal-derived corticosterone (CORT) or exogenously given CORT in cytoplasm and nuclei. GC induce in the SC the predominantly glial enzymes glycerolphosplate dehydrogenase (GPDH) and ornithine- decarboxylase (ODC). However, comparison of the GC-R of the SC and hippocampus revealed two fundamental differences: in vivo, uptake of (3H)-CORT by nuclei was 7-8 fold higher in hippocampus than in the SC; in vitro, transformation of the GC-R to the DNA- binding form was enhanced by RNAse treatment in the hippocampus but failed to affect it in the SC, implying that translocation of the hippocampal R is improved by removal of RNA. This step may be faulty in the SC, accounting for a reduced nuclear localization and favoring cytoplasmic retention of the GC-R of possible biological significance: previous data showed that GC induction of ODC in the SC required protein synthesis but was not inhibited by actymomycin D. The present proposal intends to unravel the basis for these differences, and also apply present knowledge of GC action in the SC to an animal model of human motor neuron disease such as the wobbler mutant mouse.
Specific aims of the project are: (l) to examine the R subtypes binding (3H)-CORT and (3H)-dexamethasone (DEX) in the SC and hippocampus, considering that in the former, type II or low affinity may predominate, and type I or high affinity prevail in the hippocampus. Stereoselective markers of types I and II sites will be employed to differentiate the R; (2) to study the cause for the resistance to RNAse action of the SC, R separation and structure will be analyzed by electrophoresis and gradient ultracentrifugation before and after RNAse treatment, to disclose if the R is a ribonucleoprotein as it seems to be in the hippocampus and other GC-responsive targets; (3) based on the suggestions that GC-R in the SC may be mostly glial, whereas those in hippocampus mostly neuronal, binding to type I and II sites and the RNAse effect will be examined in gradient-separated glial and neuronal populations; (4) finally, considering that the wobbler mouse is a suitable model of multiple sclerosis, a disease benefited from GC therapy, we will determine in the SC of mutants and littermates:abundance of R subtypes, transformation of the R to the DNA-binding form, R structure, induction of enzymes (ODC, GPDH) and effect of GC during the course of the disease. These experiments may furnish information for future human biochemical studies which at the moment are totally lacking.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS020866-05
Application #
3401553
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
1984-08-01
Project End
1991-01-31
Budget Start
1990-05-01
Budget End
1991-01-31
Support Year
5
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Institute of Biology and Exper Medicine
Department
Type
DUNS #
City
Buenos Aires
State
Country
Argentina
Zip Code
Gonzalez Deniselle, M C; Gonzalez, S; Piroli, G et al. (1997) Glucocorticoid receptors and actions in the spinal cord of the Wobbler mouse, a model for neurodegenerative diseases. J Steroid Biochem Mol Biol 60:205-13
Gonzalez, S; Grillo, C; Gonzalez Deniselle, M C et al. (1996) Dexamethasone up-regulates mRNA for Na+,K(+)-ATPase in some spinal cord neurones after cord transection. Neuroreport 7:1041-4
Gonzalez Deniselle, M C; Gonzalez, S L; Piroli, G G et al. (1996) The 21-aminosteroid U-74389F increases the number of glial fibrillary acidic protein-expressing astrocytes in the spinal cord of control and Wobbler mice. Cell Mol Neurobiol 16:61-72
Gonzalez, S; Coirini, H; Gonzalez Deniselle, M C et al. (1995) Time-dependent effects of dexamethasone on glutamate binding, ornithine decarboxylase activity and polyamine levels in the transected spinal cord. J Steroid Biochem Mol Biol 55:85-92
Gonzalez, S; Grillo, C; De Nicola, A G et al. (1994) Dexamethasone increases adrenalectomy-depressed Na+,K(+)-ATPase mRNA and ouabain binding in spinal cord ventral horn. J Neurochem 63:1962-70
Ferrini, M; Gonzalez, S; Antakly, T et al. (1993) Immunocytochemical localization of glucocorticoid receptors in the spinal cord: effects of adrenalectomy, glucocorticoid treatment, and spinal cord transection. Cell Mol Neurobiol 13:387-97
Ferrini, M; Gonzalez, S; De Nicola, A F (1993) Estradiol increases glucocorticoid binding and glucocorticoid induction of ornithine decarboxylase in the rat spinal cord. Life Sci 52:677-85
De Nicola, A F (1993) Steroid hormones and neuronal regeneration. Adv Neurol 59:199-206
Gonzalez, S L; Ferrini, M; Coirini, H et al. (1992) Regulation of flunitrazepam binding in the dorsal horn of the spinal cord by adrenalectomy and corticosteroids. Brain Res 589:97-101
Moses, D F; Gonzalez, S; McEwen, B S et al. (1991) Glucocorticoid type II receptors of the spinal cord show lower affinity than hippocampal type II receptors: binding parameters obtained with different experimental protocols. J Steroid Biochem Mol Biol 39:5-12

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