mRNA expression of fibroblast growth factors and hepatocyte growth factor in rat plantaris muscle following denervation and compensatory overload.

We addressed the question of whether hypertrophy induced by compensatory overload differs according to innervation status, and how fibroblast growth factors (FGF) and hepatocyte growth factor (HGF) mRNAs are expressed in the rat plantaris muscle during overload (OL) and/or denervation. Male Wistar rats were divided into four groups (Normal-Cont, Normal-OL, Denervated-Cont, and Denervated-OL). according to the plantaris denervation and/or overload. Three weeks later, plantaris weight in Denervated-Cont and Denervated-OL was significantly lower than in the Normal-Cont. The muscle weights in the Normal-OL were higher than in the Normal-Cont. The muscle weights in the Denervated-OL were higher than in the Denervated-Cont. Three days after the treatment, FGF-2, FGF-6, FGF-7 and HGF mRNAs in the Normal-OL were significantly higher than those in the Normal-Cont. FGF-2, FGF-6, FGF-7 and HGF mRNAs in the Denervated-OL were also significantly higher after 3 days than those in the Denervated-Cont. After 7 days, FGF-2, FGF-5, FGF-6, FGF-7 and HGF mRNAs were significantly higher in the Normal-OL than those in the Normal-Cont. At 21 days, FGF-1, FGF-6 and HGF mRNA levels were significantly increased. In the Denervated-OL, FGF-2, FGF-7 and HGF mRNAs at 7 days, and FGF-2 mRNA at 21 days were significantly higher than those in the Denervated-Cont. FGF-2 and FGF-6 mRNA levels decreased significantly following denervation; however, FGF-1, FGF-5, FGF-7 and HGF mRNA levels increased and maintained this increase for the 21-days treatment period. Muscle hypertrophy was thus induced by compensatory overload irrespective of innervation status, possibly in association with certain FGFs and HGF. The differential mRNA expression patterns of FGFs and HGF observed following compensatory overload and/or denervation suggest distinct roles for individual FGFs and HGF in muscle hypertrophy and/or atrophy.