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PSYC270 > Neuroendocrinology > Flashcards

Neuroendocrinology Flashcards

1
Q

Describe Berthold’s experiement

A

Studied chickens in 1849
Group 1: Castrated before adulthood
Group 2: Castrated, autotransplant
Group 3: Castrated, heterotransplant
Groups 2 and 3, new vascular supply and normal development
Group 1, no mating or fighting, smaller body
Conclusions:
1. Testes can be transplanted
2. Transplanted testes can function and produce sperm
3. Nerves are not necessary for testicular function (were cut)
New hypothesis: Testes make “secretory blood-born product”
Strengths: Easy to measure DV, used auto and heterotransplant
Weakness: no control group (sham operation)

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2
Q

Describe Young’s experiement

A

Guinea pig sexual behavior in 1959
Adult males show mounting with testosterone (T) manipulations
- Adult females do not respond to T manipulations; lordosis
Hypothesis: Hormonal events early in development are important for reproductive behaviors as adults
- Gave T or oil (control) to pregnant guinea pigs
- All female pups had their ovaries remove and given estradiol and progesterone as adults
Ovaries removed + Prenatal T = reduced lordosis and increased mounting
- Testes removed + T = decreased mounting
- Testes removed + estradiol + progesterone = lordosis

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3
Q

What are hormones?

A

Chemical secreted by cells in one part of the body and conveyed by blood to influence other cells for long lasting changes

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4
Q

What do protein and peptide hormones do?

A

Attach to membrane receptors and activate a second messenger within a cell
ex. GnRH, CRH, ACTH, insulin

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5
Q

Autocrine mediation

A

The same cell/cell type that secreted the hormone is effected

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6
Q

Paracrine mediation

A

Cells secrete chemicals that affect adjacent cells

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7
Q

Endocrine mediation

A

Secrete into bloodstream and target distant cells

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8
Q

Ectocrine mediation

A

i.e pheromones are released into the air and affect other animals

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9
Q

Monoamines

A

Made from 1 amino acid

ex. Epinephrine (adrenal), melatonin (pineal), dopamine (adrenal)

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10
Q

Lipid based hormones

A

ex. Prostaglandins

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11
Q

Steroids

A

Made by enzymes from cholesterol

ex. Glucocorticoids, androgens, estrogens progestins

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12
Q

Describe the effect of steroids

A
  1. Bind to membrane receptors exerting rapid effects
  2. Enter the cells and activate certain kinds of proteins in the cytoplasm
  3. Bind to receptors that bind to chromosomes to activate or inactivate genes
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13
Q

How do hormones affect behaviour?

A

Hormones can effect sensory systems, CNS (signal processing), motor response
Behaviour can effect hormone secretion
- Bidirectional

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14
Q

Describe the General Adaptation Syndrome

A

Hans Selye and stress:

- Stress is the non specific response to the body to any demand made upon it and is due to the adrenal glands 1. Alarm/initial stage 2. Resistance 3. Exhaustion
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15
Q

Describe the Alarm stage of GAS

A
  • Adrenal glands release epinephrine, thus stimulating the sympathetic nervous system
    • Also release cortisol, increasing blood glucose to provide extra energy
    • Releases aldosterone; important for maintaining blood salt and volume
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16
Q

Describe the Resistance stage of GAS

A
  • Sympathetic response declines, but continues to release cortisol
    • Decrease activity to maintain state
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17
Q

Describe the exhaustion stage of GAS

A
  • Individual is tired, inactive and vulnerable

- The nervous system and immune system no longer have the energy to sustain a response

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18
Q

HPA axis

A

Acts more slowly than the sympathetic nervous system, but dominates the response to prolonged stressors

Hypothalamus → CRH → Anterior pituitary → ACTH → Adrenal cortex → Cortisol + DHEA

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19
Q

How do cortisol and DHEA work

A
  • Cortisol and DHEA act in opposition
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20
Q

Role of adrenal glands

A

In HPA axis
Progesterone → Corticosterone → Aldosterone
→ Cortisol

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21
Q

Adrenal medulla

A

On inside of adrenal gland

Secretes adrenomedullary hormone

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22
Q

Adrenal cortex

A

Where steroids are produced
On outside of adrenal gland
Effects of glucorticoids take longer but last longer
Contains:
Zona glomerulosa + Zona fasciculata +Zona reticularis

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23
Q

Zona glomerolosa

A

Secretes aldosterone: Mineral balance

24
Q

Zona fasiculata

A

Secretes corticosterone and cortisol (glucorticoids)

Mobilize glucose + Suppress of immune system

25
Q

Zona reticularis

A

Secretes DHEA

26
Q

adrenomedullary hormone

A

Secretes monoamines and catecholamines from tyrosine

ex. Epinephrine, norepinephrine, dopamine

27
Q

Male/Female Hormones

A

Testes produce more androgens than ovaries, and ovaries produce more estrogen, adrenal glands produce both
Males: aromatase in the brain, progesterone in the blood, and a local production of estradiol from plasma testosterone
Females: synthesize androgens in ovaries (precursors to estradiol), testosterone and androgens in the blood and aromatase in the brain

28
Q

HPG axis males

A

Hypothalamus → GnRH, GnIH → Anterior pituitary → LH, FSH → testes → regulates gamete and sperm production and testosterone

29
Q

Testes

A
  • Produce androgens that increase the growth of the tests, causing them to produce more androgens (positive feedback)
  • Produce Mullerian-inhibiting hormone (MIH) that causes Mullerian ducts to degenerate
    Contains leydig calls and seminiferous tubules
30
Q

Leydig cells

A

Located between seminiferous tubules

- Contains all the enzymes to make testosterone from cholesterol

31
Q

Seminiferous tubules

A

Where sperm is made

32
Q

GnRH in cichid fish

A

2 types of males; territorial and non territorial determined by their social environment during development and adulthood which regulates appearance, behaviour, growth and reproduction
Territorial fish: large GnRH neurons
- Get smaller + testes shrink + no reproduction if they are placed in an environment where they become non territorial (ie. they are no longer the biggest)
Non territorial fish: small GnRH neurons
- Get larger if they are put in an environment and become territorial

33
Q

GnRH mRNA gene express in cichid fish

A

In preoptic area:
- See mRNA with in situ hybridization
- Neurons are larger in territorial fish than non territorial fish, with more GnRH present in territorial fish
Use PCR to quantify how much mRNA is in a region

34
Q

Testosterone

A
  • Differentiation of external genitals depends on testosterone levels (high=male)
  • Testosterone → dihydrotestosterone
    • High = tubercle grows into penis and scrotum develops
    • Low = tubercle grows into clitoris and labia develops
      Promotes male patterns and inhibits female patterns in early development
      Part of negative feedback system
35
Q

HPG axis females

A

GnRH → Anterior pituitary → LH + FSH → Ovary → Estradiol

  • Estradiol is used in negative feedback but used in positive feedback during mentration
36
Q

Ovaries

A
  • Primary follicle is not developed
  • Mature follicle is about to be release
    Contains Theca cells + Granulosa cells
  • If ovum is fertilized → corpus leteum
    • Produces progesterone to promote pregnancy
37
Q

Theca cells

A

Produce androgens

38
Q

Granulosa cells

A

Androgens → estradiol + estrogen using aromatase

39
Q

Hypothalamus + Hormones

A

Releases small peptide hormones into the local blood system → regulate anterior pituitary
- eg. GnRH, CRH, GHRH
Transports peptides directly to posterior pituitary through axons → secreted into systemic blood system

40
Q

Posterior Pituitary

A
  • Made of neural tissue
  • Neurons in the hypothalamus synthesize oxytocin (OT) and arginine vasopressin (AVP), posterior pituitary releases them
  • Cell bodies (paraventricular and supraoptic nucleus) have axons extending to the posterior pituitary to release OT and AVP to general circulation without vasculature
41
Q

Anterior pituitary

A
  • Made of glandular tissue
  • Synthesizes 6 hormones that flow through the blood to the anterior pituitary
    • Stimulate or inhibit the release of other hormones
      Contains Median eminence/primary plexus
42
Q

Median eminence/primary plexus

A
  • Connection from axons of the hypothalamus → anterior pituitary
  • Where the hypothalamus releases hormones to anterior pituitary as a private blood supply
43
Q

Wolffian ducts vs Mullerian ducts

A

Mullerian ducts: Precursors to female internal structures

Wolffian ducts: Precursors to male internal structures

44
Q

SRY gene

A

On Y-chromosome that causes undifferentiated gonads to develop into testes
Females do not have SRY gene so gonads develop into ovaries and Wolffian ducts degenerate

45
Q

Organizing vs Activating effects

A

Organizing: Produce long lasting structural effects, usually younger in life, sensitive periods
Activating effects: More temporary, continuing only while the hormone is present or shortly after
Adulthood affects

46
Q

Sensitive periods

A

Period when an animal is sensitive to organizing effects, usually pre/post natal
ex. 1st trimester where sec hormones determine the development of male or female genitals

47
Q

2D: 4D ratio

A
  • 2D: index finger, 4D: ring finger
  • Ratio of lengths is different between men and women
    • Women = 1
    • Men = 0.98 (4D longer than 2D)
48
Q

Hormone Transport and release

A
  • Lipid soluble hormones use carrier proteins to travel through the blood whereas protein and peptide hormones are soluble in the blood
  • Lipid soluble hormones not stored, protein and peptide hormones are stored in vesicles and released in response to a stimulus
  • 90% of glucocorticoids are bound to a protein
49
Q

Types of Hormone receptors

A
  • Protein and peptide receptors, Steroid hormone receptors
50
Q

Protein and peptide hormone receptors

A 
3 domains
    - Extracellular: binds ligand
    - Transmembrane
    - Cytoplasmic: enzyme activates intracellular proteins via phosphorylation
    Regulated, don't last forever
51
Q

Steroid hormone receptor

A

Intracellular and Membrane-bound receptors

52
Q

Intracellular steroid receptors

A
  • Within the cell, regulate gene expression via hormone response elements
    - Long lasting, >30 min
    3 Domains: C-terminal, Central, N-terminal
    HRE: located on DNA where ligand/receptor complex binds to the promotor region to regulate gene expression
53
Q

Membrane bound steroid receptors

A

In plasma membrane or mitochondria

    - Regulates enzymes, fast acting
    - Observed in the effects of corticosterone on newt mating behaviour
        - Corticosterone decreases clasping (mating) behaviour quickly
54
Q

Neurosteroids

A

Steroids synthesized in the brain

Etiene Baulieu

55
Q

Etiene Baulieu

A
  • Observed that rats have decreased levels of DHEA in blood and increase in the brain
  • He looked at orchidectomy and adrenalectomy in rats but still saw high levels of DHEA in the brain
  • Hypothesized that DHEA is made from cholesterol in the brain

PSYC270 (6 decks)

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