L9.1 Growth promoting agents Flashcards
1
Q
Definitions:
Anabolic agents
Ergogenic aids
Stimulant
Desensitisation
Downregulation
A
- Anabolic agents: ↑muscle size & str
- Ergogenic aid: allows body to train/perform at a higher level
- Stimulant: Temporarily ↑Funtional activity/efficiency of physiological systems
- Densenitisation: ↓adrenoceptor function (occurs following activation)
- Downregulation: ↓receptors
2
Q
Anabolic steriods
A
- Testosterone:
- Endogenous levels: promotes bone & muscle growth
- Exogenous administration: Stimulates protein synthesis → ↑muscle size & str
- Analogues: Nandrolone, Oxandrolone, Stanozolol
- Precursors: DHEA, androstenedione
- Clin:
- Hypogonadal men
- Low [testosterone] in older men & HIV infected men
3
Q
Anabolic steriods: Mechanism
A
- Direct → Androgen receptor in skeletal muscles
- Stimulated by testosterone & 5DHT
- Receptor stimulation → ↑protein synthesis ∴ ↑muscle mass
- Indirect → Modulate gene expression of autocrine & paracrine via IGF-1
- Alters secretion of other hormones (cortisol) that suppresses skeletal muscle growth
4
Q
Anabolic steroids: beneficial effects
A
- Muscle hypertrophy (↑protein synthesis)
- Ca2+ deposition in bones
- Lipolysis (↑lean body mass)
- ↑RBC prodction (↑O2 carrying capacity)
5
Q
Anabolic steroids: Side effects
A
- (from abuse: 100-350mg/day)
- *Some studies show no androgen therapy on muscle function despite hypertrophy
- Liver dysfunction
- Testicular atrophy
- ↑body hair, male pattern baldness, gynaecomastia (male breast growth)
- Acne
- ↓HDL cholesterol levels
6
Q
Anabolic steroids: Medicinal adminstrative levels
A
- Admin levels: (medicinal)
- Endogenous: 7mg/day
- Males: 4-10mg/day
- Females: 0.04-0.12mg/day
7
Q
Growth hormone
A
- From hypothalamus → Stimulate somatotrophin (GH) → from ANT pituitary
- Somatostatin inhibits GH
- Clin:
- ↑muscle strucutre, limited therapeutic potential
- No clinical evidence for enhancement in sports (taken for lipolytic & anabolic characteristics)
- Hard to detect
- Natural substance: stimulated by exercise, diet
8
Q
Growth hormone: Mechanism
A
- Binds 2 receptors → dimerisation
- Release somatomedins (IGF-1)
- Lipolysis
- ↑lean body mass
- Bone growth
9
Q
Growth hormone: side effects
A
- Gigantism (pre-puberty)
- Acromegaly (Post-pubety excess GH produced)
- Organomegaly (enlargement of organs)
- Hypertension (↑Na+ reabs)
- Collagen deposition
10
Q
Growth hormones: Admin levels
A
- Admin levels: 250mg-1g/day in athletes
- Cycles with other drugs (testosterone, IGF)
11
Q
IGF-1
A
- (Growth factor with structural homology to insulin)
- Normal growth & repair of muscles, mediates GH action → synergistic action → GH loses function without insulin
- Clin:
- ↑muscle mass & str
- ↑oxidative capacity
- ↑muscle function in laminin deficient MD mice
- V. $$
12
Q
IGF-1: Mechanism & Side effects
A
- Mechanism: Bind IGF-1 to receptor → ↑protein synthesis, ↓degradation → ↑muscle mass
- Anabolic mechanisms through the inhibition of protein breakdown
- Side effects: May cause growth of existing tumour
13
Q
B2-agonists
A
- (clenbuterol, fenoterol, formoterol)
- Fenotrol → ↑fast twitch & slow twitch → ↑Spread of contraction/relaxation
- IV injection → ↑↑anabolic effects
- Clin:
- Therapeutic for sarcopenia
- True muscle hypertrophy → ↑ab solute force producing capacity
- Slow → fast fibre transitions
- Enhance repair of muscles
- Therapeutic for sarcopenia
14
Q
B2-agonist: beneficial effects
A
- May reverse hypertrophy
- ↑Protein syn & ↓Protein degradation (inhibits both Ca2+ dependent proteolysis & foxo mediated E3 transcription)
- ↑SR Ca2+ ATPase activity
- Hypertrophic effect attenuated after 4 weeks
15
Q
B2-agonist: side effects
A
- Cardiac Hypertrophic (20%)
- Muscle tremors (↑HR)
- Peripheral vasodilation → ↓MAP
