Alessandro moreschi aka "?"
- what is special about him?
- what does he demonstrate?
Opera singer - "the last castrato"
- He was castrated before he reached sexual maturity to preserve his beautiful voice.
- He demonstrates the effect that hormones have on development (in this case, voice).
What is the difference between organizational effect and activational effect? Name an example of each.
Organizational effect - occurs early in development, having permanent effects (ex. in uterus, testosterone masculinizes brain)
Activational effects - short-term hormonal effects - reversible. Effects of removing testes and reimplanting them in male roosters.
1. What did he infer?
2. What was the study design and results?
3. How did he know it wasn't because of neural transmission?
- 1. Inferred that a substance excreted by glands could affect targets at a distance (hormones)
- 2. 3 groups of roosters. (1) control-normal (2) removed testes --> "capones" did not replace (3) removed testes than reimplanted.
1 and 3 looked the same in terms of comb, mounting behavior, aggression, and crowing.
Because he surgically removed it from the normal site of the body - had not been reinnervated. Had to have been traveling through blood supply.
What are the six principles of hormone action?
- 1. Reciprocal - there's a reciprocal relationship between hormones and behavior
- 2. Coordinating - hormones are coordinating molecules.
- 3. Hormones affect probability of behavior
- 4. Hormonal action occurs gradually with long-lasting effects
- 5. Hormones regulate their own secretion
- 6. Hormones are secreted cyclically.
Describe how hormones act reciprocally.
- Hormone release changes behavior which changes experience which changes hormone release - cycle continues.
- (loser effect - lower testosterone) - same in observing fans and sexual behavior.
Describe how hormones act as coordinating molecules:
1. Where is this seen and what does this coordinate and what does it affect?
2. What's another reason as to why they're coordinating molecules? (2)
- 1. Seen in organizational effects - coordination of physical morphology - affects secondary sexual characteristics.
- 2. Hormones travel at a distance and have many targets - allowing them to have widespread effects coordinating many functions and systems simultaneously.
Hormones affect probability of behavior:
1. What don't they do?
2. When do they affect probability?
3. Is there a correlation between amount of hormone and behavior?
- 1. CAUSE behavior
- 2. In a certain context (i.e., seasonal)
- 3. No, not a 1:1 ratio
How do hormones regulate their own secretion:
1. 2 mechs
2. Which is most common? How does this work?
3. Which is seen during ovulation?
- 1. Positive and negative feedback
- 2. Negative feedback: brain has set point for that time of day/year --> tells glands to secrete certain amount of hormone --> brain and glands detect that hormone and readjust signals accordingly
- 3. Positive feedback
Compare hormonal communication vs. neural communication?
What do they have in common? (2) Explain one of them.
1. Hormones are slower, longer-lasting and analog (wide secretions with wide effects)
2. Neural communication is faster, short-lasting, and binary (all-or-nothing)
Both use receptor mechanisms and chemical mechanisms.
Receptor mechanisms - structure of signaling molecules of hormones and neural pathways are the same, so response mechanisms will be the same!!!!!!
What are the two enzymes dealing with testosterone? What happens if it reaches a cell expressing one or the other?
- How is this important?
1. Aromatase (testosterone --> estradiol) and 5a-reductase (testosterone --> dihydrosteosterone)
If testosterone reaches cell expressing aromatase, will turn into estradio.
Important for sexual differentiation and behavioral/activational effects of testosterone
What are the different types of hormones that we need to know in this class? (3) Name a fact about each about how its synthesized.
Name 4, 2, and 3 examples of each.
Peptide hormones - oxytocin, vasopressin, hypothalamic releasing/inhibiting, and leptin - like peptide NTs, expressed in cells genetically.
Amines - norepinephrine and melatonin - synthesized from AAs (no specific genes)
Steroids: androgens, estrogens, cortisol - hydrophobic, all derived from cholesterol, produced by a particular cell determined by which enzymes that cell expresses.
What are the important steroid hormones that we need to know that are derived from cholesterol? (7)
What are the 3 receptors and what do they each interact with?
Androgen receptor - testosterone and dihydrotestosterone
Estradiol receptor - estradiol
progesterone receptors - progesterone
What does an athlete taking for doping?
Androstenedione - testosterone precursor.
How do hydrophilic hormones interact with receptors?
Which can affect gene transcription?
Hydrophilic - Binds to metabotropic receptors on cell surface activating secondary cascade - rapid effects. Can affect gene transcription.
Hydrophobic(steroids) - diffuse through plasma membrane, binds to receptor in cytoplasm, complex diffuses into nucleus, binds to hormone response element, eliciting transcriptional regulation. - slower.
What do the following organs do in endocrine system?
1. Hypothalamus (1)
2. Pineal gland (2)
3. Pituitary gland: Anterior (1 function by four places) & Posterior (2)
4. Thyroid (3)
5. Adrenal cortex (3)
- 1. Hypothalamus - controls hormone secretions
- 2. Pineal gland - reproductive maturation and bodily rhythms
- 3. Anterior pituitary - hormone secretion by thyroid, adrenal cortex, gonads, growth; posterior pituitary - water & salt balance
- 4. Thyroid - growth & development, metabolic rate.
- 5. Adrenal cortex - salt & carb metabolism, inflammatory rxns.
What are examples of adrenal hormones? (3)
Corticosteroids, epinephrine, norepinephrine
1. What does adipose tissue secrete?
2. What is this substance a signal of?
3. What does increased adipose tissue cause?
4. What does it affect most?
5. What are two other things affected? Why?
- 1. Leptin
- 2. Signal of energy reserves
- 3. Increased leptin secretion - but doesn't have as much of an effect on obese people
- 4. Food intake (decreases)
- 5. Puberty and reproductive ability (both obese & underweight have difficulty getting pregnant b/c brain-pituitary-gonad (BPG) axis is very sensitive to energy levels.
1. Where does hypothalamus first secrete hormones?
2. What is the role of this structure?
3. What happens after it acts upon the anterior pituitary?
4. What are tropic hormones?
- 1. Median eminence
- 2. To take chemical signals to interact with cells in anterior pituitary - it links the hypothalamic neurons and anterior pituitary.
- 3. Releases hormones into general circulation.
- 4. Tropic hormones act upon glands.
What gland releases oxytocin and vasopressin?
Where are these 2 hormones synthesized?
1. What is the BPG (brain pituitary gonad) axis important for?
2. Describe associated reproductive pattern (triggers, time frame, etc)
3. Draw picture of gonadal activity vs. time and when actual breeding season is.
2. Triggered by external cues (light
- best indicator of season, rainfall , temp etc) --> gonadal activity increases to prepare for breeding season (takes long time to change neural circuits, growing gonads, creating gametes) to enhance reproductive potential ---> most animals use this method.
Describe dissociated reproductive pattern. Example?
1. When are gametes produced?
2. When does reproduction occur?
3. What happens after coitus?
4. Is the reproductive window short or long?
- Example - red-sided garter snake.
- 1. Before hibernation
- 2. Right after hibernation
- 3. Prepares to make gametes again while gonads are still working
- 4. VERY SHORT - within hours of waking up after hibernation
1. What is the role of GnRH? (2)
2. What type of hormone are the answers from above?
3. Why is BPG axis simpler in males than females?
4.What feedback mechanism do both males and females use for BPG axis?
5. In males, how does GnRH release occur? How often? Through what special link? How does htis affect release of other cells?
- 1. Acts on gonads to release FSH and LH.
- 2. Gonadotropins
- 3. Because once it's active, it's tonically active until the end of the season.
- 4. Thermostat feedback model
- 5. Cyclically (in pulses every 1-2 hrs) - causes cyclic release of gonadotropins in pulses too. Through electrically coupled cells.
1. Draw male GnRH system (9)
Draw female GnRH system (10)
Describe the experiment that tells us how testosterone regulates peripheral tissues and behaviors? 3 groups
Is this true for humans? why or why not?
1. Castrated rat + DHT (dihydrotestosterone) - can restore secondary sexual traits (neurons in spinal cord that innervate penis), but no desire to reproduce bc no DHT action on brain.
- 2. Castrated rat + estradiol - restores sexual behavior, not peripheral sexual capacity
- 3. Testosterone- both sexual behavior and peripheral traits
No, because humans can reproduce without estradiol.
1. What is required for ovulation?
2. What is progesterone's role in the BPG axis?
3. Females with higher progesterone levels vs. females with higher estradiol - which is found to be pheremonally most attractive?
4. What happens when females were exposed to male scent?
5. What part of menstrual cycle doesn't vary? What part DOES vary?
6. What substance has positive feedback during menstrual cycle? What is its function and what does it cause?
- 1. LH Surge
- 2. Negative feedback to pituitary.
- 3. Higher estradiol
- 4. Decreased latency between LH surges - more relaxed, less stressed
- 5. Ovulation and menstruation - previous menstruation and next ovulation.
- 6. Estradiol --> increases GnRH --> increases LH and FSH for the LH surge necessary for ovulation
1. In humans, what is pineal gland innervated by? (2)
2. What is its main function? (2)
3. How does melatonin affect reproductive seasons ex in winter? Through what mechanism? Who is this important for? How does it affect humans?
4. What is the relationship between melatonin, screentime, and BPG?
- 1. Autonomic NS (specifically the sympathetic NS)
- 2. Timekeeper (helps shift from day to night) and keeps track of seasonal changes
- 3. In winter: longer nights --> less light --> more melatonin --> inhibition of BPG axis by increasing BPG sensitivity in brain to negative feedback.
Important for seasonal breeders. Thought to cause early puberty in humans.
4. Increased screentime --> decreased melatonin --> less inhibition of BPG axis --> overactivity leads to increased reproductive cancer rates
1. What tissue is responsible for regulating epinephrine and norepinephrine? What nervous system do these hormones play a large role in?
2. How does stress play a role in the Brian-Pituitary-Adrenal axis?
- 1. Medulla - sympathetic nervous system in autonomic NS. These hormones play a huge role in stress.
- 2. Stress --> CRH release (corticotropin releasing hormone - primary hormone for activating this axis) --> stimulates ACTH (adrenocorticotropic hormone) --> stimulates adrenal gland to produce corticosteroids.
What are the two types of corticosteroids - name an important example of each?
- 1. Mineralocorticoids (aldosterone) - targets kidney for water & electrolyte balance.
- 2. Glucocorticoids (cortisol) - contributes to GNG and inhibits immune response (metabolically expensive system).
What is the whole point of the stress response?
= To anticipate the need to recover homeostasis after stressor ends.
Why is stress always bad?
When is stress bad? What can it lead to? (2) What specific disease - why does this disease occur? What do you have high levels of (1 physical, 1 emotional)? Is there negative feedback of ACTH?
LOL ITS NOT HAHHAAHHA I TRICKED YOU - it's generally good bc it keeps animal alert and responsive to environment.
Chronic stress leads to long-term inhibition of immune response and inhibition of BPA axis. Cushing's disease occurs when cortisol produced by BPA is not detected by BPG and there is no negative feedback of ACTH.
You have high levels of glucocorticoids (no negative feedback and high levels of ACTH) and high levels of depression.
How do you test for Cushing's disease?
What would you see in a normal person?
What does chronic stress and cortisol inhibit? What can help combat these effects?
ACTH challenge - inject glucocorticoids/cortisol and measure changes in ACTH levels.
In a normal person, there would be an initial burst of glucocorticoids, followed by a decrease in ACTH and CRH
Chronic stress and cortisol inhibit neurogenesis in hippocampus. SSRIs and exercise by blocking stress's effects on neurogenesis.
What do suicidal people have high levels of?
Draw picture of how light projects onto pineal gland.