[Relationship between serum thyroid hormone and GH-IGF axis, growth failure in nephrotic rats].

OBJECTIVE

To investigate the individual effects of malnutrition, nephrosis and glucocorticoid therapy on serum thyroid hormone, and explore the relationship between serum thyroid hormone and GH-IGF axis, growth failure in nephrotic rats.

METHODS

Twenty-four male Sprague-Dawley (SD) rats were randomly divided into control group, pair-fed group, doxorubincin-induced nephrotic group (nephrotic group) and dexamethasone-treated nephrotic group (des-treated group). Serum T3/T4, GH and IGF-I were measured by RIA, serum IGFBPs were measured by Western ligand blot, liver GHR and IGF-I/IGFBPs mRNA were analyzed by radio-receptor assay and RT-PCR respectively.

RESULTS

1. Serum thyroid hormone was low in pair-fed group, lower in nephrotic group and lowest in des-treated group except for high serum T4 in pair-fed group. 2. Serum thyroid hormone was positively related with liver GHR, IGF-I/IGFBP-3 mRNA and serum IGF-I/IGFBP-3, and negatively related with serum IGFBP-2. 3. Serum thyroid hormone was positively related with nose-tail length and weight (both P < 0.01).

CONCLUSIONS

The hypothyroidism is a possible mechanism of reducing serum IGF-I levels and biologic action, and resulting in growth failure in nephrotic syndrome.