Cytomorphometry of skeletal muscle: The influence of age and testosterone on the rat M. levator ani

Galavazi, G.; Szirmai, J.A.

doi:10.1007/bf00560157

Cited by 36 publications

(7 citation statements)

References 30 publications

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“…This is in line with a previous result showing an increase in the myonuclear number in the trapezius muscle of athletes who used steroids compared to those who did not (Kadi et al 1999b). Similarly, Galavazi and Szirmai (1971) and Joubert and Tobin (1989) showed that testosterone treatment increased the number of myonuclei in the rat levator ani muscles.…”

Section: Discussionsupporting

confidence: 91%

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Kadi¹,

Bonnerud²,

Eriksson³

et al. 2000

Histochemistry and Cell Biology

132

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The purpose of this study was to investigate the immunohistochemical expression of androgen receptors (AR) in human vastus lateralis and trapezius muscles and to determine whether long-term strength training and self-administration of androgenic-anabolic steroids are accompanied by changes in AR content. Biopsy samples were taken from eight high-level power-lifters (P), nine high-level power-lifters who used anabolic steroids (PAS) and six untrained subjects (U). Myonuclei and AR were visualised in cross-sections stained with the monoclonal antibody against AR and 4',6-diamidino-2-phenylindole. The proportion of AR-containing myonuclei per fibre cross-section was higher in the trapezius than in the vastus lateralis (P<0.05). In the trapezius, the proportion of AR-containing myonuclei was higher in P compared to U and in PAS compared to both P and U (P<0. 05). On the contrary, in the vastus lateralis, there were no differences in AR content between the three groups. Myonuclear number in both muscles was higher in P compared to U and in PAS compared to both P and U (P<0.05). In conclusion, AR content differs greatly between human neck and limb muscles. Moreover, the regulation of AR-containing myonuclei following training and self-administration of androgenic-anabolic steroids is muscle dependent.

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Section: Discussionsupporting

confidence: 91%

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Kadi¹,

Bonnerud²,

Eriksson³

et al. 2000

Histochemistry and Cell Biology

132

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“…Most studies on MND during animal growth in a single species found no difference in nuclear length with body mass (Galavazi and Szirmai, 1971;Manta et al, 1987;Matthew and Moore, 1987;Rosser et al, 2002). Rosser et al found that throughout chicken development, from neonatal to adult, myonuclei had very similar mean lengths (Rosser et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Growth patterns and nuclear distribution in white muscle fibers from black sea bass, Centropristis striata: evidence for the influence of diffusion

Priester

Morton

Kinsey

et al. 2011

Journal of Experimental Biology

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SUMMARYThis study investigated the influence of fiber size on the distribution of nuclei and fiber growth patterns in white muscle of black sea bass, Centropristis striata, ranging in body mass from 0.45 to 4840g. Nuclei were counted in 1m optical sections using confocal microscopy of DAPI-and Acridine-Orange-stained muscle fibers. Mean fiber diameter increased from 36±0.87m in the 0.45g fish to 280±5.47m in the 1885g fish. Growth beyond 2000g triggered the recruitment of smaller fibers, thus significantly reducing mean fiber diameter. Nuclei in the smaller fibers were exclusively subsarcolemmal (SS), whereas in larger fibers nuclei were more numerous and included intermyofibrillar (IM) nuclei. There was a significant effect of body mass on nuclear domain size (F118.71, d.f.3, P<0.0001), which increased to a maximum in fish of medium size (282-1885g) and then decreased in large fish (>2000g). Although an increase in the number of nuclei during fiber growth can help preserve the myonuclear domain, the appearance of IM nuclei during hypertrophic growth seems to be aimed at maintaining short effective diffusion distances for nuclear substrates and products. If only SS nuclei were present throughout growth, the diffusion distance would increase in proportion to the radius of the fibers. These observations are consistent with the hypothesis that changes in nuclear distribution and fiber growth patterns are mechanisms for avoiding diffusion limitation during animal growth.

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“…Although genital staging of puberty (Tanner, 1962) was not employed in the present study, the increased muscle strength was most noticeable in boys in whom puberty was well advanced, as evidenced by deepening of the voice and coarsening of the skin. In the levator ani muscle of the rat, testosterone has been shown to have a direct effect on muscle development (Wainman and Shipounoff, 1941;Venable, 1966a, b;Gori, Pellegrino, and Pollera, 1969;Galavazi and Szirmai, 1971). It is therefore reasonable to suppose that the enhanced muscle strength at puberty results from the increased levels of circulating testosterone which are known to occur at this time (Wieland, Chen, Zorn, and Hallberg, 1971).…”

Section: Discussionmentioning

confidence: 99%

Muscle strength in boys of different ages

McComas

Sica

Petito

1973

Journal of Neurology, Neurosurgery & Psychiatry

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SUMMARY Isometric twitch contractions have been studied in extensor hallucis brevis muscles of 32 healthy male subjects aged between 3 and 25 years. The maximum twitch tensions were found to increase gradually with age and then to undergo marked enhancement at puberty. After puberty little further change occurred. In the youngest children examined the twitch contraction times were already within the adult range, though the half-relaxation times were prolonged.As children grow older they become stronger, but few systematic observations have been made of this process.Recently, we have had the opportunity to record isometric twitch tensions in healthy boys of various ages, some of whom served as controls for a study of Duchenne dystrophy (McComas, Sica, and Currie, 1971). The advantage of measuring twitch tension is that it does not depend on the cooperation of the subject and therefore can be made in relatively young children. The results of this study are felt to be of some interest in that they reveal a marked increase in muscle force which occurs at puberty. METHODSThirty-two healthy males were studied with ages ranging from 3 to 25 years. The isometric twitch was recorded from the extensor hallucis brevis (EHB) muscle using the technique of Sica and . The initial length of the muscle was increased by fully plantar-flexing the first metatarsophalangeal joint. It has previously been shown that in a young subject the optimum length is greater than the maximum length attainable .No correction has been made for variations in the distance between the recording point on the big toe and the metatarsophalangeal joint. In older, and larger, subjects this distance would be greater and hence the recorded tension would be a relatively

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Cytomorphometry of skeletal muscle: The influence of age and testosterone on the rat M. levator ani

Cited by 36 publications

References 30 publications

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

The expression of androgen receptors in human neck and limb muscles: effects of training and self-administration of androgenic-anabolic steroids

Growth patterns and nuclear distribution in white muscle fibers from black sea bass, Centropristis striata: evidence for the influence of diffusion

Muscle strength in boys of different ages

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