| Summary: | Thesis (MSc)--University of Stellenbosch, 2007. === ENGLISH ABSTRACT: Human studies on the response of muscle to contusion injury are limited,
probably due to the large variability in injury severity and the non-specificity of
clinical symptoms reported. To circumvent this problem, several experimental
animal models have been designed to study muscle damage and regeneration
after contusion injuries. However, the majority of techniques currently used to
induce contusion injury are very invasive and therefore not optimal. Furthermore,
published studies regarding clinical treatment of such injuries are limited. The
main aims of this study were therefore: a) to establish and characterise an in vivo
model of non-invasive contusion injury, and b) to assess the effect of pre-injury
chronic administration of the antioxidant supplement Oxiprovin™ - a natural
grape seed extract (GSE) - on skeletal muscle recovery after experimentallyinduced
injury.
Two groups of male Wistar rats were subjected to 14 days of oral administration
of isovolaemic placebo (sterile isotonic saline) or GSE (20 mg/kg/day) prior to
induced contusion. Contusion injury was induced with the mass-drop technique,
and recovery parameters assessed for up to 14 days post-injury. Placebotreated
rats on average exhibited a 56 % higher creatine kinase (CK) activity
when compared to the GSE-treated rats when area under the curve (AUC) was
calculated for 14 days post-injury (p < 0.001). In the placebo group, plasma
oxygen radical absorbance capacity (ORAC) was unchanged over time, but
muscle ORAC was significantly increased by day 7 post-injury (p < 0.001). In the
GSE group, a significant decrease in both plasma (p < 0.01) and muscle ORAC
(p < 0.001) was evident 4 hr after injury, followed by a significant increase by day
3 (p < 0.05 and p < 0.001 respectively). CD34+ satellite cell (SC) numbers (quiescent and activated) peaked earlier in GSE-treated rats when compared to
placebo-treated rats (4 hours vs. day 7 post-injury). Total satellite cell number
(CD56+) also peaked earlier in GSE-treated rats than in placebo-treated rats (4
hours vs. 3 days post-injury), while M-cadherin+ SC numbers (quiescent,
activated or proliferating) in both treatment groups were significantly increased 4
hours post-injury (p < 0.001), but more so in the placebo group. In GSE-treated
rats when compared to placebo-treated rats, newly generated muscle fibres
(displaying central nuclei and MHCf
+) both appeared (day 3 vs. day 7 post-injury)
and peaked in number (day 3 vs. day 7 post-injury; increase from baseline p <
0.001 for both) earlier.
The results of this study demonstrate that we have successfully established an in
vivo model for non-invasive contusion injury in rats. Furthermore, we have shown
that Oxiprovin™: a) increased the ability to scavenge reactive species generated
after injury and b) resulted in the activation of satellite cells and formation of
newly generated muscle fibres at an earlier time point, thus accelerating the
recovery of skeletal muscle after a standardised contusion injury. === AFRIKAANSE OPSOMMING: Eksperimente aangaande die reaksie van spier op kneusings in mense is beperk,
waarskynlik as gevolg van die groot verskeidenheid simptome wat mag voorkom
en die verskille in die ernstigheid van beserings. Ten einde hierdie problem te
oorbrug, is verskeie eksperimentele diermodelle opgestel om kneusings en die
herstel van spier daarna te ondersoek. Die tegnieke wat grootendeels vandag
gebruik word om kneusings te veroorsaak, maak inbraak op die spier deur die
spier te ontbloot voor besering, en is dus nie ideaal nie. Daar is ook nie baie
bewyse aangaande die mees geskikte manier om so ‘n besering klinies te
behandel nie. Die doel van hierdie studie was dus om: a) ‘n in vivo model van
kneusings op te stel en te omskryf, en b) die effek van chroniese toediening van
die antioksidant Oxiprovin™ - ‘n natuurlike druifsaad ekstrak (DSE) – op die
herstel van skeletspier na ‘n kneusing te ondersoek.
Twee groepe manlike Wistar rotte is onderwerp aan mondelikse toediening van
isovolemiese plasebo (steriele isotoniese soutoplossing) of DSE (20 mg/kg/dag)
vir ‘n tydperk van 14 dae voor kneusing. Kneusing is geïnduseer met die “massdrop”
tegniek, en parameters van herstel is ondersoek tot en met 14 dae na
besering. Plasebo-behandelde rotte het gemiddeld 56 % hoër kreatien kinase
(KK) aktiwiteit in vergelyking met DSE-behandelde rotte (p < 0.001), toe die
oppervlak onder die kurwe (OOK) tot en met 14 dae na besering bereken is.
Geen verskil oor tyd is in die plasebo groep opgemerk toe plasma suurstof
radikaal absorpsie kapasiteit (SRAK) bepaal is nie, maar ‘n betekenisvolle
toename in spier SRAK teen dag 7 (p < 0.001) is waargeneem. ‘n Betekenisvolle
afname in beide plasma (p < 0.01) en spier (p < 0.001) SRAK van die DSE is
teen 4 hr waargeneem, gevolg deur ‘n betekenisvolle toename teen dag 3 na besering (p < 0.05 en p < 0.001 onderskeidelik). Die aantal CD34+ satelliet selle
(SS – rustend en geaktiveerd) het beduidend vroeër in die DSE groep gestyg in
vergelyking met die plasebo groep (4 uur vs. 7 dae na besering). Die totale
aantal SS (CD56+) het ook vroeër in die DSE-behandelde rotte as die plasebobehandelde
rotte gestyg (4 uur vs. 3 dae na besering), terwyl die aantal Mcadherin+
SS (rustend, geaktiveerd of prolifererend) betenisvol gestyg het in
beide groepe teen 4 uur (p < 0.001) na besering, maar hoër in die plasebo groep
was. Die aantal nuutgevormde spiervesels (met sentraal geleë nukleï en MHCf
+)
het beide vroeër verskyn en gepiek in die DSE-behandelde rotte in vergelyking
met die plasebo-behandelde rotte (dag 3 vs. dag 7 na besering).
Die resultate van hierdie studie dui aan dat ons instaat was om ‘n in vivo model
van nie-indringende kneusing in rotte op te stel. Verder, het ons ook bewys dat
Oxiprovin™ toediening die vermoë verleen het om: a) reaktiewe spesies wat na
beserings gevorm word, meer doeltreffend te verwyder en b) satelliet selle vroeër
te aktiveer en die vorming van nuwe skeletspiervesels te vervroeg, om sodoende
die herstel van skeletspier na ‘n gestandardiseerde kneusing vinniger te
bewerkstellig.
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