A 22-year old male bodybuilder has come to the hospital because he believes his testicles are less than half their original size. He is worried that they will continue to shrink and affect his fertility and sex drive. Patient admits to injecting himself with anabolic steroids over the last few months. He would like to know what caused the shrinkage and what other side effects he could experience.
Upstream causes
Anabolic steroid use
Elevated levels of testosterone cause the brain to send signals that tell testicles to stop producing testosterone.
Background information
General functions of the Endocrine System
secrets hormones directly into the bloodstream
Regulates development, growth and metabolism
Maintains homeostasis of blood composition and volume
Controls digestive process
Controls reproductive activities
The two types of hormones
Water-soluble Hormones
Lipid-Soluble Hormones
Steroids
formed from cholesterol
Proteins
Biogenic amines (except thyroid hormone)
made of amino-acid chains
derived from amino-acid that is modified
Interaction with target cells
diffuse across plasma membrane
bind to intracellular receptors located in cytosol or nucleus
forms hormone-receptor complex
hormone-receptor complex formed with target cell binds to DNA sequence in regions of chromatin call hormone-response elements
transcription of mRNA occurs
translation occurs
change results in either an alteration of cell structure
or a shift in target cells' metabolic activities
Interaction with target cells
unable to cross plasma membrane
hormone binds to plasma membrane receptor
series of biochemical events occur across membrane called signal transduction pathway
the hormone becomes the first messenger
binding to the receptor becomes the second messenger
the second messenger modifies some cellular activity
The Major Endocrine glands
Pituitary gland
Pineal gland
melatonin
regulates sleep-wake cycle
Thyroid gland
T3- Triiodothyronine and T4- Tetraiodothyronine
increases metabolic rate
calcitonin
decreases blood calcium levels
Parathyroid gland
parathyroid hormone
increases blood calcium levels
Adrenal gland
Adrenal cortex
Aldosterone
Feedback loop concept
Negative feedback loop
a stimulus causes an action in the body that is the opposite of the stimulus
Positive feedback loop
a stimulus is reinforced to continue in the same direction
Up and down-regulation
Up-regulation
The process in which a target cell increases the amount of receptors
prevents understimulation
helps to maintain a normal cellular response
Down-regulation
The process in which a target cell decreases the amount of receptors it has
prevents over-stimulation
helps to maintain a normal cellular response
Downstream effects
With continued use of anabolic steroids
Kidney problems or failure
Liver damage or tumors
Enlarged heart
High blood pressure
Changes in blood cholesterol
Increased risk of heart attack or stroke
can lead to build up of plaque in the blood vessels
increased risk of heart attack
increased risk of stroke
increased risk of peripheral artery disease
can lead to the kidneys not working at all
body fills with extra water and waste
can cause seizures or coma
liver becomes inflamed
fibrosis occurs
diminished blood flow
cirrhosis occurs
complete liver failure
liver cancer
heart has to work harder to pump blood
can lead to heart attack
heart muscles become weak
can lead to heart disease and stroke
Sex drive can be effected
increased sex drive
decreased sex drive
erection problems
may cause fertility problems
decreased or stopped sperm production
With discontinued use of anabolic steroids
May experience withdrawal symptoms
mood swings
restlessness
loss of appetite
craving for steroids
feelings of anxiety or apathy
Sperm production normalizes after a year
Testicles begin to regenerate lost tissue
liver damage usually reverses
limited or no production of testosterone causes testicular shrinkage
Reasons for patient to abuse steroids
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Other potential effects
hair loss
development of breast
organ damage
infertility
wanted to gain more muscle mass
other body builders use steroids
pressure to meet personal goals
Patient experienced plateau with current muscle gain
regulates blood Na+ and K+ levels
Cortisol
stress response
Androgen
maturation of reproductive system
Adrenal medulla
Epinephrine and norepinephrine
fight or flight response
Pituitary gland (anterior)
Follicle-stimulating hormone
controls development of both ooctye and ovarian follicle within ovaries
Pituitary gland (posterior)
Antidiuretic Hormone
decreases urine output
Oxytocin
contraction of smooth muscle in the uterus
Luteinizing hormone
induces ovulation
Andrenocorticotropic hormone
stimulates adrenal cortex to release cortisol
Thyroid-stimulating hormone
stimulates thyroid gland to release thyroid hormone
Prolactin
regulates mammary gland growth
Growth hormone
induces growth
Feedback loop at work and its effects
continued use of steroids causes a negative feedback loop
this tells the brain to stop producing testosterone because of high levels
elevated levels of testosterone also cause down regulation of the receptors
Specific hormonal pathway from hypothalamus to testes
Hypothalamus releases Gonadotropin-releasing hormone (GnRH)
GnRH stimulates anterior pituitary
FSH(follicle-stimulating hormone) and LH (luteinizing hormone) are released
these hormones act on gonads to stimulate development of sperm and cause the testes to release testosterone