Behavioral Endocrinology and Immunoassays Quiz

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Questions and Answers

What is a key characteristic of the 'removal and replacement' technique in behavioural endocrinology?

It relies on observing changes in behavior after administering a hormone agonist.

It focuses primarily on quantifying hormone receptor densities in different tissues.

It enables causal interpretations by measuring differences before and after hormone source manipulation. (correct)

It involves measuring hormone levels indirectly using competitive binding assays.

In the context of an immunoassay, what is the primary purpose of using an animal's immune system?

To directly measure the concentration of hormones in the animal's blood.

To generate antibodies that can specifically bind to a substance of interest. (correct)

To create a standardized solution for hormone replacement therapy.

To induce a state of hormonal hyper-responsiveness in the animal.

During the radioimmunoassay (RIA) process, what is the significance of using a 'hot ligand'?

It allows for the precise quantification of the cold ligands through radioactive emissions. (correct)

It ensures complete binding of all antibody sites in the test tube.

It functions as an antagonist that blocks any binding of cold ligand.

It acts a control to verify the quantity of the cold ligand.

Why is it important to use increasing concentrations of a 'cold standard' in a radioimmunoassay?

To produce a standard curve correlating radioactivity and concentration through competition. Signup and view all the answers

In a radioimmunoassay, what occurs when more cold testosterone is added to the test tube?

There is less hot testosterone binding to antibodies, leading to a reduction in measured radioactivity. Signup and view all the answers

What fundamental principle of the immune system is harnessed in immunoassays?

The specificity of antibodies to bind to particular molecules or antigens. Signup and view all the answers

Rosalyn Sussman Yalow was awarded the Nobel Prize for which contribution to science?

The pioneering work that lead to the development of immunoassays. Signup and view all the answers

What is a standard curve used for in the context of radioimmunoassays?

To allow for the quantification of hormone concentrations in unknown samples based on measured radioactivity. Signup and view all the answers

What is the primary distinction between direct and indirect immunohistochemistry?

Direct immunohistochemistry requires only one antibody, while indirect requires multiple antibodies. Signup and view all the answers

In the context of the provided material, what does an 'agonist' do at a receptor site?

It mimics the effects of a naturally occurring chemical messenger, like a hormone or neurotransmitter. Signup and view all the answers

Which of the following techniques is used to visualize hormone receptor locations using a radio labeled hormone?

Autoradiography Signup and view all the answers

The concentration of estradiol is measured in units of picograms per milliliter. This is also equivalent to:

picomoles per liter Signup and view all the answers

Which statement about the ventromedial hypothalamus is correct, based on the information provided?

The density of the estrogen receptors in the ventromedial hypothalamus is high, and plays an important role in female social and sexual behavior. Signup and view all the answers

What does 'mass percentage' most commonly entail, in the area of endocrinology?

The amount of hormone in 100 milliliters of plasma or serum. Signup and view all the answers

Caffeine acts at the adenosine receptor as a(n):

Antagonist Signup and view all the answers

Hormones such as luteinizing hormone (LH) and follicle stimulating hormone (FSH), which are produced by the pituitary gland, are measured in what units?

units/liter Signup and view all the answers

Which technique uses radioactive substances to visualize brain activity?

PET Signup and view all the answers

What is the primary function of the parathyroid hormone (PTH)?

Raise blood calcium levels. Signup and view all the answers

What is a characteristic of endocrine glands?

They release hormones directly into the bloodstream. Signup and view all the answers

Which of the following brain imaging techniques would be best for visualizing large brain structures?

MRI Signup and view all the answers

What is used to visualize cells that have recently been active in animal brain imaging?

Immediate early genes (IEGs). Signup and view all the answers

Which of the options are NOT a type of brain imaging technique?

IEG IHC Signup and view all the answers

Which method uses magnetic fields to measure brain function?

fMRI Signup and view all the answers

What is a primary role of calcium in the body as described in this content?

Supporting the function of the heart, kidneys and nervous system. Signup and view all the answers

Which of the following hormones is primarily responsible for maintaining the corpus luteum during early pregnancy?

Chorionic gonadotropin (CG) Signup and view all the answers

What is a primary function of chorionic somatomammotropin (CS) in mammals?

Stimulating the onset of maternal behaviors Signup and view all the answers

Which of these steroid hormones is primarily involved in the body's stress response?

Cortisol Signup and view all the answers

Which of the following is correct about the structure of steroid hormones?

They consist of three 6-carbon rings and a conjugated 5-carbon ring. Signup and view all the answers

What is a characteristic of steroid hormones that necessitates the use of carrier proteins in the bloodstream?

They are lipophilic and do not dissolve well in blood. Signup and view all the answers

Where are progesterone-type hormones produced in the brain?

Glial cells Signup and view all the answers

Which of the following hormones is detectable by pregnancy tests?

Chorionic gonadotropin (CG) Signup and view all the answers

What role do androgens play in the human body?

Can be converted into other steroids like testosterone and estrogen and are important for sex characteristics and sex drive. Signup and view all the answers

What is the primary function of Sertoli cells within the testes?

Development of sperm and release of inhibin Signup and view all the answers

Which hormone is directly stimulated by Luteinizing Hormone (LH) in Leydig cells?

Testosterone (an androgen) Signup and view all the answers

During the follicular phase of the ovarian cycle, what is the role of granulosa cells?

Convert androgens to estrogens using aromatase Signup and view all the answers

What is the primary hormone produced by the corpus luteum?

Progestins Signup and view all the answers

Which of these hormones is primarily responsible for softening pelvic ligaments during pregnancy?

Relaxin Signup and view all the answers

Which of the following is NOT a known effect of testosterone?

Promoting development from Follicular phase to Luteal phase Signup and view all the answers

What effect does inhibin have on hormone secretion?

It suppresses hormone secretion from the hypothalamus and pituitary. Signup and view all the answers

What is the role of FSH in the ovaries?

Converts androgens to estrogens via aromatase in granulosa cells Signup and view all the answers

Which pituitary hormone is NOT named after the target it affects?

GH Signup and view all the answers

What is the primary effect of vasopressin on the kidneys?

Increases sodium absorption. Signup and view all the answers

Which statement accurately describes the relationship between GnRH and the pituitary hormones?

GnRH stimulates the release of LH and FSH. Signup and view all the answers

What is the role of heat shock proteins (HSP) in steroid hormone signaling?

They keep steroid receptors inactive in the absence of a hormone. Signup and view all the answers

What is the precursor molecule responsible for the synthesis of ACTH, beta-endorphin, and met-enkephalin?

POMC Signup and view all the answers

How does ethanol consumption affect vasopressin release?

It inhibits vasopressin release, leading to increased urination. Signup and view all the answers

Which of the following best describes the action of steroid hormones within a target cell?

The hormone binds to a receptor in the cytoplasm, then the complex interacts with DNA. Signup and view all the answers

What are the two hormones released by the posterior pituitary?

Vasopressin and Oxytocin Signup and view all the answers

What process specifically stimulates the release of oxytocin from the posterior pituitary to initiate milk ejection?

Tactile stimulation of receptors in the nipple. Signup and view all the answers

Which of the following statements is true regarding the intermediate lobe of the pituitary gland?

It is prominent in amphibians and involved in colour-changing. Signup and view all the answers

Study Notes

Research Techniques in Behavioral Endocrinology

Removal and replacement: Possible to make causal interpretations. Removal of the hormone source allows researchers to measure changes before and after removal.

Immunoassay

Way to detect specific biological substances in blood and tissues.
Routinely used to measure hormone levels.
A method that uses the principles of the immune system to quantify or visualize specific substances.
An example is using one animal's immune system to create antibodies to a substance of interest from another animal (e.g., testosterone in rat, injected into rabbit).
Procedures:
- Take testosterone from a rat and inject it into a rabbit.
- The rabbit's body creates antibodies.
- Take blood from the rabbit.
- Rabbits' antibodies are extracted, purified, and tagged with a detectable label to identify them.

Radioimmunoassay (RIA)

Type of immunoassay uses radioactivity to detect chemical substances in body tissues.
Pioneered by Rosalind Sussman Jalloh (Nobel Prize in Physiology or Medicine in 1977).
Requires a "hot ligand" (radioactively labeled ligand) and a "cold standard" (non-radioactively labeled ligand).
Known amounts of the cold standard are added to tubes in increasing concentrations.
Each tube contains the same amount of testosterone antibody.
The hot and cold ligands compete for binding sites on the antibody.
The excess fluid is removed, and the amount of radioactivity bound to the antibody is measured.
More cold testosterone added leads to less binding of the hot testosterone, less radioactivity detected.
Plotting known concentrations of the cold standards versus the radioactivity produces a standard curve, crucial for determining unknown sample concentrations.

Enzyme-linked Immunosorbent Assay (ELISA)

Quantifies hormones in various tissues (hair, nails, feces, blubber).
Uses color intensity as a label (instead of radioactivity).
Uses small sample quantities.
Standards of known concentrations generate a standard curve for sample quantification.
A darker colour indicates a stronger hormone concentration.

Hormone Alteration Experiments

Experiments to determine if verbal aggression affects testosterone levels.
Subjects are randomly assigned to insult or neutral conditions.
Saliva samples are collected.
ELISA is used for testosterone quantification.
Intra-assay and inter-assay variations are considered for error prevention.

ELISA Applications

Pregnancy tests (detecting HCG).
Early ovulation tests.
COVID-19 tests.

Hormone Conversions

Deci (d), centi (c), milli (m), micro (μ), nano (n), pico (p), femto (f). Unit conversion factors for relative concentrations (such as pg/mL, ng/mL) in plasma/serum (often measured as 1mL or 1L).

Hormone Mass Percentage

The amount of a hormone in 100 mL of plasma or serum.
Conversion between mass percentage and other units (e.g., pmol/L) is often needed and can be done via referencing conversion factors (available online).

Immunohistochemistry

Type of immunoassay that visualizes hormone receptors or proteins in tissues by applying labeled antibodies.
Useful for determining the location and distribution of hormone receptors in the brain.
Direct detection uses a single antibody targeting the target receptor.
Indirect detection uses multiple antibodies & large binding proteins (like horseradish peroxidase) for visualization using microscopy techniques.

Autoradiography

Technique used to locate hormone receptors by injecting a radiolabeled hormone.
Tissues of interest are then exposed to radioactive material sensitive film to visualize receptor locations in tissues.
This technique is useful for studying hormone receptor distribution.

Brain Imaging (Humans)

Non-invasive techniques including CT (X-rays), PET (positron emission), MRI (magnetic fields), fMRI (magnetic fields, BOLD), and EEG (electrical activity) for detecting brain activity and structures.

Brain Imaging (Animals)

Immunohistochemistry uses immediate early genes (e.g., ZENK, EGR-1, NGFI-A, and C-FOS) after neuron activation for indicating neuronal activity in specific brain areas.
Zebra finches experiments using NCM (Nucleus for the Control of Memory) to illustrate how auditory signals affect neurons.

Hormone Receptor Localization Techniques

Summary of appropriate methods (immunoassay/ELISA, immunohistochemistry, autoradiography, human & animal brain imaging) to determine hormone receptor location in the body, noting criteria to decide on the approach like size of target structures.

Hormone Availability Factors

Factors influencing hormone availability in blood:
- Lipophilicity (affects storage & release),
- Steroid breakdown (catabolism),
- Carrier protein affinity & capability,
- Binding strength to carrier proteins that inhibits hormone release (inactive steroid).

Hypothalamic and Pituitary Hormones

All hypothalamic and pituitary hormones are peptides or proteins.
Hormones travel through the portal system in the brain. This pathway involves a capillary network that connects the hypothalamus to the anterior pituitary.
The hypothalamus releases releasing hormones into the portal system that trigger release of hormones in the anterior pituitary (e.g. GnRH – Gonadotropin-releasing hormone).
The anterior pituitary then releases hormones that travel via blood to other endocrine organs. The posterior pituitary releases hormones that are produced by the hypothalamus.

Hormone Receptors Types

Steroid receptors are found inside target cells, enabling direct interaction with DNA for gene transcription regulation.
Peptide receptors are embedded within the cell membrane, activating intracellular enzymes (via 2nd messengers like cAMP) for response signaling.
The two major peptide receptor types are enzyme-linked and G-protein coupled.

Hormone Receptor Mechanisms (Steroids & Peptides)

Mechanisms that explain how steroid hormones directly affect gene expression by binding and influencing DNA transcription.
Mechanisms of peptide hormone receptor activation, explaining the effects of hormones relying on second messengers (e.g. cAMP).

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Description

Test your knowledge on key concepts in behavioral endocrinology and immunoassays, including the removal and replacement technique, the significance of hot ligands, and the contributions of Rosalyn Sussman Yalow. This quiz covers essential principles, methodologies, and distinctions in the field. Perfect for students and professionals looking to reinforce their understanding of these topics.