PPT 9 - Regulation Skeletal Muscle Mass

Question 1

A variety of factors that can influence the size or mass of skeletal muscle includes:

Answer 1

Nutrition,
Resistance Exercise Training, 
Genetics,
Hormones, &
Growth & Differentiation Factors.

Question 2

Factors that influence muscle and whole body anabolism.

Answer 2

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.

Question 3

Which 2 proteins play a role in the hypertrophic adaption of muscle to heavy-resistance strength training?

Answer 3

insulin-like growth factor I (IGF-I) and growth and differentiation factor 8 (GDF-8)

Question 4

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.

Answer 4

increases, decreases

Question 5

IGF-1 and GDF-8 are involved in the ____________ response of human skeletal muscle to heavy-resistance strength training.

Answer 5

hypertrophic

Question 6

Other word for GDF-8

Answer 6

myostatin

Question 7

GDF-8 is a member of which family?

Answer 7

transforming growth factor beta (TGF-β) superfamily of secreted growth & differentiation factors (acts to properly regulate skeletal muscle mass)

Question 8

2 Roles of TGF-β

Answer 8

regulate embryonic development and maintain homeostasis of tissues in adult animals.

Question 9

Is there any expressionof GDF-8 in adipose tissue?

Answer 9

yes, but very small amounts

Question 10

The Myostatin Knockout Mouse

Answer 10

Mighty Mouse
Super Mouse
X-Mouse

Question 11

The Mutants are ______x heavier than the Wild-Type mice.

Answer 11

2-3

Question 12

Explain hypertrophy results with the mice.

Answer 12

Cranial tibialis
MT > W-T: 7 %.

Gastrocnemius
MT > W-T: 22 %.

Question 13

GDF-8 is mainly expressed in which muscle?

Answer 13

skeletal

Question 14

Loss of GDF-8 causes what?

Answer 14

increases the mass of tissues producing this factor, in particular, skeletal muscle.

Question 15

The increase in skeletal muscle mass is due to

Answer 15

hypertrophy and hyperplasia

Question 16

GDF-8 functions specifically as a (positive/negative) regulator of skeletal muscle mass during development & growth.

Answer 16

negative

Question 17

Where is myostatin synthesized?

Answer 17

in skeletal muscle

Question 18

myostain secretion (release) is required at which point in the mice’s life?

Answer 18

before and after birth and during adulthood.

Question 19

Mutations in the myostatin gene of several _________ breeds exist.

Answer 19

cattle

Question 20

blood concentrations of the myostatin protein are increased in _____________ men.

Answer 20

HIV-infected

Question 21

The injection of an antibody that binds to myostatin in adult mice results in what?

Answer 21

blocked signal, resulting in an increase in muscle size.

Question 22

When would blocking or inhibiting of myostatin signaling pathway ever be useful?

Answer 22

for the prevention and treatment of obesity and type 2 diabetes.

as well as to treat muscular dystrophy, Neuromuscular diseases, & Cachexia.

Question 23

Some myostatin roles include:

Answer 23

1) Regulation of skeletal muscles.
2) Muscle Disuse
3) Sarcopenia
4) cachexia
5) regeneration
6) hypertrophy

Question 24

Muscle disuse

Answer 24

atrophy of skeletal muscle associated with limb immobilization, such as having a leg in a plaster cast, or the weightlessness of outer space.

Question 25

Cachexia

Answer 25

atrophy of skeletal muscle associated with cancer or AIDs.

Question 26

Because myostatin is found in various animals such as chickens, turkeys, cows, & pigs… it may provide the agriculture industry with what?

Answer 26

it may provide the agricultural industry with the capability to produce greater yields (amounts) of meat in these animals.

Question 27

Myostain (increase/decrease) in heavy resistance training.

Answer 27

decrease

Question 28

Inhibition of myostatin in adult mice (increases/decreases) skeletal muscle mass and strength.

Answer 28

INCREASES

Question 29

They noticed that mice treated with the myostatin inhibitor gained ____% more weight than the control mice.

Answer 29

10, which is a result of HYPERTROPHY ONLY