Psychendocrinology Flashcards
What are hormones?
Chemical messengers, generally synthesised by specialised glands, carried by the circulation to target tissues and organs
What are the main endocrine glands where hormones are sysnthesised?
Hypothalamic – Pituitary – Thyroid axis (HPT axis) Hypothalamic – Pituitary – Adrenal axis (HPA axis) Hypothalamic – Pituitary – Gonadal axis (HPG axis) 
What are some key differences between neural communication and endocrine/hormonal communication?
Neural communication - Signal travels to a specific location - Rapid - measured in ms - All or none Hormonal/endocrine communication - Signal travels everywhere (hormone molecules dispersed) - Slower - measured in seconds and minutes - Analogue messages - graded strength
How do hormones work?
Hormones only affect cells that have the receptor protein that recognises the hormone to alter cell function The levels of most hormones vary rhythmically throughout the day (e.g. melatonin - pineal gland) Each hormone has multiple effects on different cells and behaviours - Additionally, a single type of behaviour can be affected by different hormones
What was the first experiment involving behaviour endocrinology?
Conducted by Berthold (1849) - castrated cockerels 3 groups - control, completely castrated, one testis returned Control: combs, mounting behaviour, aggression, crowing behaviour Castrated - no comb, no mounting, no aggression, weak crowing One testis - normalised phenotype
What was the significance of Berthold’s experiment?
Returning a testis reversed the phenotype change. However the re-implanted testis was in an abnormal body site, disconnected from neural innervation Thus reasoned that testes release a signal that has widespread effects throughout body -> hormone
What are the types of hormones?
Peptide hormones - composed of strings of amino acids Steroid hormones – cholesterol derived hormones Amine hormones - composed of a single amino acid modified into a related molecule (molecule that acts as a hormone) 
What are endocrine or neuroendocrine cells’ mechanism of functioning?
Simply release hormones into the bloodstream
What are paracrine cells’ mechanism of functioning?
Paracrine hormones act locally on nearby cells
What are autocrine cells’ mechanism of functioning?
Autocrine signals act directly on cell that released them; provide feedback to the cell from which they were released
What are peptide and amine hormones’ mechanism of function?
Not lipid soluble (although a few amine hormones are). They bind with receptors on the cell membrane to exert effects. Second messenger systems
What are steroid hormones’ mechanism of function?
Steroids are lipid soluble and can freely cross the phospholipid bi-layer. They bind to target receptors inside the target cell (intracellular).
How do hormones alter cellular function?
By affecting the growth, proliferation, and differentiation of cells.
What are the inputs controlling hormone secretion?
Changes in circulating concentrations of ions (e.g. Na+) or nutrients (e.g. glucose) Direct innervation from the nervous system
What do direct innervation from the central nervous system do?
In the case of neurosecretary cells in the hypothalamus Receive direct inputs from other areas of brain (amygdala and hippocampus) Determine whether they should fire and release hormones
An example of another hormone acting on the endocrine cell do?
HPT axis Hypothalamus –TRH—> anterior pituitary —TSH–> thyroid gland –thyroid hormone—> target cells
What is negative feedback?
It plays an important role in regulation of most hormonal systems. An increase in a hormone produces feedback so the level substance is reduced (feedback switches the production off) Acts like a thermostat
What is stress? And some examples?
Any circumstance that upsets the body’s balance (homeostasis) e.g. - exposure to extreme cod or heat, threatening psychological states
When was the word stress first applied to physiology?
Walter B. Cannon Coined term ‘fight or flight’ Developed the concept of homeostasis
Walter B. Cannon?
First used word ‘stress’ in physiology Coined term ‘fight or flight’ Developed the concept of homeostasis Demonstrated the role of epinephrine in the stress response
What is a stressor?
Anything which disrupts physiological balance
What is stress defined as?
The general state of stressors provoking a stress response
What is a stress-response?
The body’s adaptations designed to reestablish the balance
What are some types of stressors?
Acute stressful event (e.g. public speaking) Chronic stress (e.g. daily hassles) Both lead to HPA-axis and increase in SNS activation
The physiological outcome of stress?
HPA-axis and increase in SNS activation
Mechanism for action - HPA axis?
HPA axis - mechanisms of action?
Hippocampus and amygdala in paraventricular nucleus -> corticotropin-releasing factor (CRF) in anterior pituitary -> Adrenocorticotropic hormone (ACTH) increased -> adrenal cortex -> glucocorticoids
Corticotropin-releasing factor (CRF) effects?
Causes ACTH production
Suppresses appetite
Increases subjective feelings of anxiety
Adrenocorticotropic hormone (ACTH) effects?
Increases secretion of steroid hormone from the adrenal cortex
Glucocorticoid (i.e. cortisol) effects?
Gluconeogenesis
Immunosuppression
Negative feedback
High levels can kill neurons in the hippocampus
What is the HPA-axis and SNS activation good for?
For acute physiological stress the HPA-axis and SNS provide excellent stress response
What is the HPA-axis and SNS activation maladaptive for?
For chronic and psychosocial stress the response is maladaptive
Normal vs crowded train study?
- Studied epinephrine levels
- In crowded train, there was 10% increase in the number of passesngers
- Normal group: 20% increase in epinephrine levels compared to control
- Crowded group: 65% increase in epinephrine levels compared to control
Epinephrine and NE and exam stress?
Epinephrine and NE levels peak during exam. However they increase long before the exam.
Doubling of baseline epinephrine more than 2 weeks before exam
Aren’t adaptive to situation
Trier Social Stress Test (TSST)
- TSST
- Social stressors: Public talk
- Count down backwards from 100 by 7s, angry panelists demand participants start again if wrong
- ACTH and cortisol responses
- Activation of HPA-axis
- Immediate increase in ACTH
- Stronger, more sustanced cortisol release
- Stress response is not advantageous
What cells do chronic social stress impact on?
- Hippocampal pyramidal cells
- Animal of low social status - social stress, far fewer cell bodies in hippocampus
- Glucocorticoids lead to cell death in the hippocampus
