Endocrine Disruptors and Stress Response Mechanisms

What are Endocrine Disrupting Chemicals (EDCs)?

Chemicals that can interfere with hormone systems, potentially leading to adverse health effects.

What is a significant factor in the effects of EDC exposure?

The timing of exposure, especially during critical periods of development, can have permanent effects.

Where are EDCs commonly found?

In air, food, water, clothing, furniture, cosmetics, and pesticides.

How many man-made chemicals are considered EDCs?

More than 350,000.

What are some effects of EDC exposure observed in herring gulls?

Lack of male paternal behavior, increased pre-hatchling deaths, hermaphroditic characteristics, and grotesque deformities linked to DDT.

What reproductive issues have been observed in bald eagles due to EDCs?

Dramatic decrease in hatched eaglets, indifference to courtship behaviors, and 80% male sterility.

What effects did EDCs have on alligators?

90% of eggs hatched, but half of the hatchlings died within 10 days, and males had small penises due to estrogen-like effects.

What was the purpose of prescribing DES to pregnant women?

To produce 'bigger, stronger babies,' but it resulted in reproductive tract deformities and cancers.

What reproductive issues have been found in males exposed to DES?

Reduced sperm volume, decreased mobility, altered morphology, and reduced testicular mass.

Why is it difficult to associate EDC exposure with health issues?

EDCs interfere with hormone systems without killing cells, leading to deficits that may not cause immediate outward sickness.

What are the pros of using lab animals for EDC research?

Control over exposure timing, faster life cycles, and observation of mechanistic actions and generational effects.

What are the cons of using lab animals for EDC research?

Results may not be fully analogous to humans, and bidirectional mechanisms can differ.

What health effects have been linked to PCBs in humans?

Thyroid problems, muscle weakness, sensory neuropathy, delayed cognitive development, and ADHD.

What is the traditional experimental paradigm for studying EDCs?

Administration through consumption or injection to pregnant mothers, followed by observation of offspring.

What is a potential problem with the traditional EDC experimental paradigm?

Changes in maternal behavior (like licking and grooming) can affect offspring outcomes.

What is transgenerational inheritance in the context of EDCs?

The compounding incidence of disease over generations, where new contaminants can have similar harmful effects as old ones.

What is the purpose of Tier I and Tier II reporting systems for hazardous chemicals?

Tier I requires general information about hazardous chemicals, while Tier II requires specific details about locations and storage.

What is the significance of the DES prescription case in understanding EDCs?

It highlights the long-term reproductive health consequences of EDC exposure in both females and males.

How do EDCs affect male birth ratios?

There has been a multi-year decline in male births and an increase in female births, potentially due to synthetic estrogens.

What are some behavioral changes observed in humans due to PCB exposure?

Altered sex behavior and increased hyperactivity.

What is the impact of EDCs on cognitive development?

EDCs have been linked to delayed cognitive development and difficulties in concentration.

What are some examples of EDCs mentioned in the notes?

DDT, Dicofol, and synthetic estrogens.

What is the significance of the lab research on EDCs?

It allows for controlled studies on the effects of EDCs at specific time points in development.

What is osmotic thirst and what causes it?

Osmotic thirst occurs when eating salt or sugar increases plasma osmolarity, drawing water out of cells.

What happens when water is added to the system in terms of osmolarity?

Adding water dilutes extracellular concentrations and decreases plasma osmolarity.

What are the two types of thirst discussed in the notes?

Osmotic thirst and hypovolemic thirst.

What causes hypovolemic thirst?

Loss of bodily fluids, such as from hemorrhage, vomiting, diarrhea, or perspiration.

What is required for fluid replacement in hypovolemic thirst?

Fluid replacement must be an isotonic solution.

What is osmotic dehydration?

Osmotic dehydration refers to cellular dehydration where intracellular fluid moves to the extracellular compartment.

What role do cerebral osmoreceptor cells play in thirst?

Cerebral osmoreceptor cells act as thirst sensors that send messages to the brain about dehydration.

What hormone is released in response to dehydration and what is its source?

Antidiuretic hormone (ADH) is released from the posterior pituitary.

How does ADH affect the kidneys?

ADH conserves water by increasing water permeability of the collecting duct.

What is the filtration rate of the kidneys?

The kidneys filter 30 liters of blood per hour.

What nuclei release ADH into circulation?

The supraoptic nucleus and paraventricular nucleus release ADH into general circulation.

Describe the pathway of filtrate through the loop of Henle.

Filtrate goes through the descending limb, loop of Henle, ascending limb, and distal tubule before reaching the bladder.

What occurs in the descending limb of the loop of Henle?

A lot of water leaves the filtrate due to concentration.

What happens in the ascending limb and distal tubule of the loop of Henle?

Sodium leaves the filtrate, which helps regulate water retention.

What is the relationship between sodium concentration and water retention in the loop of Henle?

The lower part of the loop has high sodium, while the higher part has lower sodium, influencing water retention.

What physiological response occurs when the kidneys do not retain enough water?

The brain signals thirst, prompting the individual to drink.

What is the difference between behavioral and physiological responses to thirst?

Drinking water when thirsty is a behavioral response, while retaining water by the kidneys is a physiological response.

What is the significance of isotonic solutions in fluid replacement?

Isotonic solutions help maintain the balance of fluids and electrolytes in the body.

How does the body sense dehydration?

The body senses dehydration through osmoreceptors that detect changes in plasma osmolarity.

What effect does ADH have on the collecting duct?

ADH increases the water permeability of the collecting duct, leading to more concentrated urine.

What triggers the release of ADH and other hormones during hypovolemic dehydration?

Baroreceptors detect low blood pressure, which triggers the brain to increase heart rate and release ADH, Renin, and Aldosterone.

What is the role of Aldosterone in the kidneys?

Aldosterone enhances sodium reabsorption in the ascending loop of Henle and raises blood pressure.

Describe the mechanism for salt retention and water absorption in response to low blood pressure.

Low blood pressure triggers baroreceptors, leading to Renin release, conversion of Angiotensinogen to Angiotensin I, and then to Angiotensin II via ACE, causing vasoconstriction and increased heart rate, followed by Aldosterone release and ADH release, enhancing salt and water retention.

What condition do Brattleboro rats exhibit due to a genetic mutation?

Brattleboro rats have diabetes insipidus, which is the inability to produce ADH, causing excessive urination and constant thirst.

What is the function of baroreceptors in the cardiovascular system?

Baroreceptors detect changes in blood pressure and trigger responses such as the Renin-Angiotensin-Aldosterone system when blood pressure is low.

How do ACE inhibitors affect blood pressure?

ACE inhibitors lower blood pressure by preventing the formation of Angiotensin II.

What is the significance of maintaining blood glucose levels?

The brain requires glucose to function, and maintaining a narrow range of blood glucose levels is critical for health.

What is hyperglycemia?

Hyperglycemia is a condition characterized by excessively high blood glucose levels.

What is hypoglycemia?

Hypoglycemia is a condition characterized by insufficient blood glucose levels.

What role does insulin play in glucose metabolism?

Insulin, produced by beta cells of the pancreas, facilitates the conversion of glucose to glycogen (glycogenesis) in the liver and fat (lipogenesis) when glucose levels are high.

What is the function of glucagon?

Glucagon, produced by alpha cells of the pancreas, raises blood glucose levels by promoting glycogen breakdown (glycogenolysis) and gluconeogenesis from amino acids.

What are the differences between Type I and Type II diabetes?

Type I diabetes is an autoimmune condition where the body cannot produce insulin, while Type II diabetes is often due to insulin resistance from poor diet and lifestyle.

What is gestational diabetes?

Gestational diabetes is a temporary form of diabetes that can occur during pregnancy, characterized by lower insulin sensitivity.

What is latent autoimmune diabetes in adults (LADA)?

LADA is a form of diabetes that is often misdiagnosed as Type II but is actually an autoimmune condition similar to Type I.

What hormones are involved in regulating energy levels?

Key hormones include insulin, glucagon, leptin, ghrelin, and CCK.

What is the function of ghrelin?

Ghrelin is produced when the stomach is empty and signals hunger to the hypothalamus, increasing before meals and decreasing after.

What is the role of leptin in appetite regulation?

Leptin is produced by fat cells and signals the hypothalamus to reduce hunger when energy stores are sufficient.

What does CCK do in the digestive process?

CCK is produced by the small intestine in response to food intake, particularly fats and proteins, and promotes enzyme release for digestion and signals fullness.

What is the difference between orexigenic and anorexigenic signals?

Orexigenic signals stimulate appetite, while anorexigenic signals suppress appetite.

What triggers hunger in the orexigenic response?

Hunger is triggered in response to the lateral hypothalamus.

What triggers satiety in the anorexigenic response?

Satiety is triggered in response to the ventromedial hypothalamus.

What are the two different avenues in stress research?

1) Biomedical field 2) Ecology/Evolution

What is the definition of stress in the context of engineering?

Stress refers to compression, tension, or shearing, with its magnitude compared to the magnitude of the force.

What is strain in relation to stress?

Strain is the deformation of a structure as a result of stress.

Who is known as the father of the stress concept?

Hans Selye.

What did Hans Selye observe about the adrenal glands in his stress research on rats?

He found that the adrenal glands in both control and stressed rats were larger due to stress-related disease.

What was a significant mistake made by Hans Selye in his research?

The notes do not specify what he did wrong.

What are the three phases of general adaptation syndrome?

1.) Alarm phase with increased glucocorticoids 2.) Resistance phase (stress response) 3.) Exhaustion phase (final consequence of prolonged stress).

What is a stressor?

Any aversive stimulus that is unpredictable and uncontrollable, with perception being crucial.

What is the stress response?

The physiological and/or behavioral response to a stressor.

What are stress effects?

The pathological consequences of a stress response, also referred to as strain.

What is the primary adrenal response?

The fight or flight response initiated through the adrenal medulla, affecting heart rate, blood pressure, and breathing.

What does the sympatho-adrenomedullary system do?

It increases heart rate, blood pressure, and breathing, releases glucose into the bloodstream, and enhances memory.

What is the mechanism of the HPA Axis?

Hypothalamus secretes CRH -> anterior pituitary releases ACTH -> adrenal cortex produces glucocorticoids and mineralocorticoids, with negative feedback to the cortex and hypothalamus.

What are the long-term responses of the HPA Axis?

Increased glucose, decreased insulin, decreased inflammatory response, and retention of sodium and water in the kidneys.

What characterizes a 'good' stress response?

Low baseline glucocorticoids, fast peak response to stressors, and quick return to baseline.

What are the three components of life history that require energy?

Reproduction, survival, and growth, which can intersect and prioritize one over the others.

What are the acute stress response effects?

Shift from anabolism to catabolism, increased heart rate, inhibited digestion and growth, altered immune function, enhanced cognition, and analgesia.

What are the chronic stress effects?

Fatigue, myopathy, diabetes, hypertension, peptic ulcers, psychosocial dwarfism, impotence, anovulation, loss of libido, impaired disease resistance, cancer, and accelerated neural degeneration.

What does the glucocorticoid level diagram illustrate?

Glucocorticoids rise and fall throughout the day with circadian variation; high levels indicate homeostatic overload, while low levels indicate homeostatic failure.

What neurological effects does acute stress have?

Behavioral changes.

What neurological effects does chronic stress have?

Structural changes in the brain, particularly in the amygdala, hippocampus, and prefrontal cortex.

How does chronic stress affect the hippocampus?

It induces dendritic atrophy and inhibits neurogenesis.

What changes occur in the medial prefrontal cortex due to stress?

Major neuronal remodeling and dendritic atrophy.

What is the role of the amygdala in stress?

It acts as the emotional control center, particularly for fear, and experiences dendritic hypertrophy during stress.

What are some factors influencing variation in stress response?

Perception of stressors and sense of control over them.

How does perception affect stress response?

The same stressor can be perceived differently by individuals; continuous experience can decrease glucocorticoid levels.

What is the significance of control in stress response?

Having control over a stressor can produce euphoria and lower glucocorticoid levels, while too much control can be detrimental.

What was demonstrated in the Executive Monkey Study?

Monkeys that could control their stressors experienced different stress responses compared to those who could not.

What was the outcome of the Executive Monkey experiment regarding stress and control?

The Executive Monkey experienced gastric ulcers and death due to the stress of control.

What was a significant problem with the Executive Monkey study's methodology?

The monkeys were not randomly assigned; they were highly motivated to be in control, leading to higher stress levels.

How does unpredictability affect ulcer development in rats?

Ulcer development is higher when shocks are not predicted.

What coping mechanism was observed in rats that had the ability to chew on something?

Rats that could chew on something developed fewer ulcers compared to those that could not.

What effect does social support have on stress levels in male baboons?

Male baboons with strong social connections have lower basal cortisol levels and age more successfully.

What is social buffering in the context of stress?

Stress is reduced during stressful situations when individuals are presented with close bond individuals.

What are the two different coping responses identified in the lecture?

Tend and Befriend, which involves seeking social support, and Fight or Flight, which involves a physiological stress response.

What genetic factor was noted in rats regarding anxiety?

Rats show high anxiety when in open spaces, and breeding high and low anxious rats can produce non-reactive and reactive offspring.