PPT 9 - Regulation Skeletal Muscle Mass Flashcards
A variety of factors that can influence the size or mass of skeletal muscle includes:
Nutrition, Resistance Exercise Training, Genetics, Hormones, & Growth & Differentiation Factors.
Factors that influence muscle and whole body anabolism.
Type & amount of amino acids,
Protein digestive properties,
Timing of nutrient intake in relation to exercise,
Timing of nutrient intake in relation to other nutrients, &
Total energy intake.
Which 2 proteins play a role in the hypertrophic adaption of muscle to heavy-resistance strength training?
insulin-like growth factor I (IGF-I) and growth and differentiation factor 8 (GDF-8)
HEAVY resistance strength training (increases/decreases) the gene expression of a form of IGF-1 and (increases/decreases) the gene expression of GDF-8 in the skeletal muscle of young adult humans.
increases, decreases
IGF-1 and GDF-8 are involved in the ____________ response of human skeletal muscle to heavy-resistance strength training.
hypertrophic
Other word for GDF-8
myostatin
GDF-8 is a member of which family?
transforming growth factor beta (TGF-β) superfamily of secreted growth & differentiation factors (acts to properly regulate skeletal muscle mass)
2 Roles of TGF-β
regulate embryonic development and maintain homeostasis of tissues in adult animals.
Is there any expressionof GDF-8 in adipose tissue?
yes, but very small amounts
The Myostatin Knockout Mouse
Mighty Mouse
Super Mouse
X-Mouse
The Mutants are ______x heavier than the Wild-Type mice.
2-3
Explain hypertrophy results with the mice.
Cranial tibialis
MT > W-T: 7 %.
Gastrocnemius
MT > W-T: 22 %.
GDF-8 is mainly expressed in which muscle?
skeletal
Loss of GDF-8 causes what?
increases the mass of tissues producing this factor, in particular, skeletal muscle.
The increase in skeletal muscle mass is due to
hypertrophy and hyperplasia
GDF-8 functions specifically as a (positive/negative) regulator of skeletal muscle mass during development & growth.
negative
Where is myostatin synthesized?
in skeletal muscle
myostain secretion (release) is required at which point in the mice’s life?
before and after birth and during adulthood.
Mutations in the myostatin gene of several _________ breeds exist.
cattle
blood concentrations of the myostatin protein are increased in _____________ men.
HIV-infected
The injection of an antibody that binds to myostatin in adult mice results in what?
blocked signal, resulting in an increase in muscle size.
When would blocking or inhibiting of myostatin signaling pathway ever be useful?
for the prevention and treatment of obesity and type 2 diabetes.
as well as to treat muscular dystrophy, Neuromuscular diseases, & Cachexia.
Some myostatin roles include:
1) Regulation of skeletal muscles.
2) Muscle Disuse
3) Sarcopenia
4) cachexia
5) regeneration
6) hypertrophy
Muscle disuse
atrophy of skeletal muscle associated with limb immobilization, such as having a leg in a plaster cast, or the weightlessness of outer space.
