Influence of muscle activity in trophic regulation of acetylcholinesterase activity in dystrophic chickens

Effects of electrical stimulation on molecular forms of butyrylcholinesterase in denervated fast and slow latissimus dorsi muscles of newly hatched chicken

The effects of denervation and direct electrical stimulation upon the activity and the molecular form distribution of butyrylcholinesterase (BuChE) were studied in fast-twitch posterior latissimus dorsi (PLD) and in slow-tonic anterior latissimus dorsi (ALD) muscles of newly hatched chicken. In PLD muscle, denervation performed at day 2 substantially reduced the rate of rapid decrease of BuChE specific activity which takes place during normal development, whereas in the case of ALD muscle little change was observed. Moreover, the asymmetric forms which were dramatically reduced in denervated PLD muscle were virtually absent in denervated ALD muscle at day 14. Denervated PLD and ALD muscles were stimulated from day 4 to day 14 of age. Two patterns of stimulation were applied, either 5-Hz frequency (slow rhythm) or 40-Hz frequency (fast rhythm). Both patterns of stimulation provided the same number of impulses per day (about 61,000). In PLD muscle, electrical stimulation almost totally prevented the postdenervation loss in asymmetric forms and led to a decrease in BuChE specific activity. In ALD muscle, electrical stimulation partially prevented the asymmetric form loss which occurs after denervation. This study emphasizes the role of evoked muscle activity in the regulation of BuChE asymmetric forms in the fast PLD muscle and the differential response of denervated slow and fast muscles to electrical stimulation.

Posthatching changes in levels and molecular forms of acetylcholinesterase in slow and fast muscles of the chicken: effects of denervation and direct electrical stimulation

The evolution of acetylcholinesterase (AChE) activity and AChE molecular form distribution were studied in slow-tonic anterior latissimus dorsi (ALD) and in fast-twitch posterior latissimus dorsi (PLD) muscles of chickens 2-18 days of age. In ALD as well as in PLD muscles, the AChE-specific activity increased transiently from day 2 to day 4; the activity then decreased more rapidly in PLD muscle. During this period asymmetric AChE forms decreased dramatically in ALD muscle and the globular forms increased. In PLD muscle, the most striking change was the decline in A8 form between days 2 and 18 of development. Denervation performed at day 2 delayed the normal decrease in AChE-specific activity in PLD muscle, whereas little change was observed in ALD muscle. Moreover, A forms in these two muscles were virtually absent 8 days after denervation. Direct electrical stimulation depressed the rise in AChE-specific activity in denervated PLD muscle and prevented the loss of the A forms. Furthermore, the different molecular forms varied according to the stimulus pattern. In ALD muscle, electrical stimulation failed to prevent the effect of denervation. This study emphasizes the differential response of denervated slow and fast muscles to electrical stimulation and stresses the importance of the frequency of stimulation in the regulation of AChE molecular forms in PLD muscle during development.

Fiber type and non-endplate acetylcholinesterase in normal and experimentally altered muscles

The non-endplate (sarcoplasmic) acetylcholinesterase (AChE) was investigated in eight different muscles of the rat. Serial consecutive sections were stained for AChE, myofibrillar ATPase (after alkaline and acid preincubation), and cytochrome C-oxidase. The following general correlation could be established: within a given muscle the sarcoplasmic AChE was highest in type IIB fibers, lowest in type I and intermediate in type IIA. Additionally, the intensity of the reaction was directly proportional to the size of the type IIA fibers. The distribution of sarcoplasmic AChE was correlated to the ATPase fiber types but was complementary to the cytochrome C-oxidase staining pattern. In single fiber preparations, accumulation of AChE at the myotendinous junction was found to occur in "cap-like" form exclusively in fibers with very low or absent sarcoplasmic AChE. To study the role of innervation in the expression of the sarcoplasmic AChE, we cross-reinnervated the extensor digitorum longus (EDL) muscle with the soleus (SOL) nerve and vice versa (X-EDL, X-SOL). In the X-EDL the sarcoplasmic AChE was transformed to that of a normal SOL as were also the ATPase and the cytochrome oxidase. Surprisingly, in the X-SOL the high AChE activity typical for a normal EDL was present after 3 weeks but decreased steadily to very low levels lacking any correlation with ATPase and cytochrome oxidase. The results suggest that the cytoplasmic AChE of the SOL muscle depends more on the load-bearing function of the muscle than on the imposed impulse pattern. There is additional evidence for a retrograde effect of the X-SOL upon its motoneurons.

Effects of percutaneous electrical stimulation on functional ability, plasma creatine kinase, and pectoralis musculature of normal and genetically dystrophic chickens

The breast musculature of genetically dystrophic Line 413 and genetically related normal Line 412 chickens were treated in three separate trials with high-frequency electrical stimulation (ES). Beginning on days 7 or 14 ex ovo, each bird received three ES treatments per week. Each stimulation cycle repeated five times per day consisted of 15 s "on" followed by 50 s "off". In the third trial only, the birds were additionally treated beginning day 3 ex ovo with either leucine (100 mg/kg) or the proteinase inhibitor Ep475 (10 mg/kg). ES significantly delayed the onset of righting disability in the dystrophic chickens. However, this improvement was temporary and could be masked by single treatments of either leucine or Ep475. Plasma creatine kinase activities were increased generally in both the stimulated normal and dystrophic birds. In two trials ES increased the relative muscle mass, and in one trial increased protein. ES had little effect on normal muscle mass or protein. However, ES treatment together with either leucine or Ep475 appeared to improve both normal and dystrophic muscle mass and protein. Furthermore ES decreased dystrophic muscle calcium but not acetylcholinesterase activity. On the other hand, ES had no effect on the total normal muscle calcium but increased normal acetylcholinesterase values. In both normal and dystrophic muscle samples, ES treatment in combination with leucine appeared to increase the mean muscle fiber diameters and number of myonuclei, and in the case of the dystrophic muscle, appeared to decrease the relative proportion of vacuolated, degenerating, and intensely oxidative histochemical fibers. In general, stimulation (especially in combination with leucine) appears to alter in varying degrees the phenotypic expression of the muscle disease exhibited in the dystrophic chicken.

Acrylamide neuropathy and changes in the axonal transport and muscular content of the molecular forms of acetylcholinesterase

Acetylcholinesterase (AChE) is present in nervous and muscular tissues of normal chickens in four main molecular forms (G1, G2, G4, and A12), distinguishable by sedimentation analysis. In the sciatic nerve of acrylamide-poisoned chickens, the anterograde axonal transport of A12 AChE was reduced by 60%, and that of G4 by 21%, compared to control values whereas the slow axoplasmic transport of G1 and G2 was unaffected. Regarding the leg muscles, only the tibialis anterior revealed dramatic alterations in the distribution of it AChE forms coinciding with a large reduction in the number of nerve endings. In acrylamide poisoning, the AChE molecular forms were considered as very sensitive markers of both axonal transport phases and of the innervation state. Our results support the hypothesis that a defect in the fast axonal transport of proteins might be involved in the degeneration process of the disease.

Delayed functional disability in dystrophic chickens receiving chemotherapy

Line 413 early-onset, genetically homozygous dystrophic chickens were given twice-daily intraperitoneal injections of the antiserotoninergic drug cinanserin, alone or in combination with methysergide. Other trials consisted of penicillamine treatment in combination with either methysergide or cyproheptadine. Chemotherapy significantly prolonged the righting ability of treated dystrophic chickens, as measured by a periodic standardized flip-test procedure. Plasma creatine kinase activities were not affected by any of the various drug treatments. However, the blood serotonin levels of the dystrophic chickens (grand mean 1.47 microgram serotonin/ml blood) were found to be significantly higher (p less than 0.001) than those in the corresponding normal chickens (0.99 microgram/ml). This finding may partially account for the antiserotoninergic drug enhancement in righting ability that was demonstrated in the drug-treated dystrophic chickens.