Enzymatic Changes in Denervated Muscle

Abstract

IntroductionIN PREVIOUS STUDIES46,11 we investigated by histochemical and quantitative biochemical means the activity of a number of enzymes of energy metabolism in the skeletal and cardiac muscles of the rat. The results defined differences between the energy metabolism of various types of skeletal muscle fibers. From the correlation of the findings with some of the physiological data available in the literature it was concluded that the differences between the energy metabolism of the skeletal muscle fibers correspond to differences between their characteristics of contraction and probably also between their innervation.The present study was undertaken with the aim of investigating the dependence of the preferential metabolism of the various types of skeletal muscle fibers upon their nerve supply. For this purpose the activity of a number of enzymes was studied histochemically and by quantitative biochemical assays in denervated muscles. The histochemical findings are described here and the quantitative biochemical results are presented in a companion paper.26 Material and MethodsThe studies were carried out in male albino rats weighing 200-250 gm. The animals were placed under light pentobarbital (Nembutal) anesthesia and using aseptic techniques the sciatic nerve of one hind limb was exposed in the thigh. A seg¬ ment of this nerve 1.5 cm in length was excised and the skin was closed with silver clips. The rats were sacrificed by ether inhalation 1, 2, 3, 4, 6, and 8 weeks later. From most animals, the gastrocnemius, plantaris, and soleus were removed together, both from the denervated and from the normal leg. The denervated muscles were placed against the normal ones and the entire block thus made was frozen on solid carbon dioxide (dry ice), mounted on ice, and cross sections 32µ thick cut in a cryostat. Each section of the block con¬ tained a cross section of the three denervated calf muscles and of their normal counterparts. Serial sections were placed directly in incubating solu¬ tions for the histochemical demonstration of the activity of the following enzymes : phosphorylase, esterase, cytochrome oxidase, and a number of dehydrogenases. In addition, acid phosphatase was studied in animals with muscles denervated for four weeks.From a few rats, the individual calf muscles were removed separately. The gastrocnemii from the normal and denervated sides were placed against each other, frozen, and mounted on ice for longitudinal sectioning. The same procedure was followed with the solei. The longitudinal sections were incubated for esterase in order to demonstrate the motor end plates, and for succinic dehydrogenase. Some of the sections incubated for succinic dehydrogenase were subsequently in¬ cubated also for esterase.The techniques used for the histochemical stud¬ ies were as follows : Phosphorylase was done by the method of Takeuchi.5"'"0 Esterase was studied by the indoxyl acetate method of Holt * using 5-bromoindoxyl acetate in tris buffer at pH 7.4. The technique was modified as suggested by Shnitka a...

Effect of Denervation or Castration on Ultrastructural and Histochemical Properties of Feline Bulbocavernosus Muscle

“…These results are difficult to compare to the present findings, since they instituted a 48-hour fast prior to sampling. Postdenervation decreases in enzymes involved in lipid metabolism have been noted in fibers with high lipid metabo lism [Romanul and Hogan, 1965], While the morphologic alterations observed in the present study were limited, our observations are consistent with previ ous findings on morphologic changes accompanying denervation atrophy of skeletal muscles [Pellegrino and Franzini, 1963;Tomanek and Lund, 1973] and cas tration atrophy of the rat levator ani muscle [Goriel al., 1967], Goriet al [1967] did not observe a degenerative process in the con tractile material of rat levator ani muscle until the late stages of castration atrophy. This is in contrast to the early appearance of degeneration of contractile material in rat skeletal muscle during denervation atrophy [Pellegrino and Franzini, 1963].…”

“…After castration, decreases in SDH in guinea pig and rat levator ani muscle have also been reported [ Chinoy et al, 1973]. Following a histochemical study of the effect of denervation on various enzy mes involved in aerobic and anaerobic metabolism, Romanul and Hogan [1965] concluded that fibers most rapidly lose those enzymes normally highest in the fiber. Whereas the present results are surprising in view of the high activity of SDH in BCM, phosphorylase activity decreased as expected.…”

Age effects on cytochrome oxidase activities during denervation and recovery of three muscle fiber types

“…The de-differentiation of muscle types apparent in this study has been described by others (e.g., Romanul and Hogan, 1965;Smith, 1965;Gauthier and Dunn, 1973;Tomanek and Lund, 1973). De-differentiation is reflected by a heterogeneous muscle fiber population becoming more homogeneous due to enzyme changes leading to the metabolic transformation of one fiber type into another, or a preferential loss of a particular fiber type (Gauthier and Dunn, 1973).…”

Superficial or deep implantation of motor nerve after denervation: An experimental study—superficial or deep implantation of motor nerve

“…This may result from a predominance of muscle fibers with high activity of glycolytic enzymes and low activity of other enzymes in peripheral localization. 15 MTeT was higher in the super®cial implantation group than in the deep implantation group (P <0.01). Recovery of neuromuscular function was best in tetanic stimulation during nerve healing, as seen in Frey et al 7 and Mc Namara et al 6 The increase in muscular function can be explained by a recruitment phenomenon, and by higher activity of glycolytic enzymes in peripheral muscle ®bers.…”

“…15 To obtain better functional recovery, experimental studies compared neurotization techniques to each other, and to other techniques of nerve repair, i.e., coaptation of nerve endings, nerve grafting, and muscular neurotization.…”