Samenvatting Behavioural Endocrinology

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Learning outcomes: the student should

Test yourself: concepts & definitions you should know

Theme 1: Introduction to Behavioural Endocrinology
be able to analyse behaviour at the four different levels of analysis of behavioural questions
(causation, development, evolution, adaptive function)

be able to identify problems associated with the determination of causation in a hormone -behaviour
interaction



CL1: Introduction (ch1)
Be aware of the historical perspectives of the studies of behaviour and endocrinology

 Hippocrates
- Founder of endocrinology
- Description of disturbed hormonal condition & its consequences
- What was Abdera suffering from (no menstrual cycle, beard formation)? => overactive
production androgens & cortisol from adrenal cortex (pituitary tumour)
- Milk prod without child => prolactin producing tumour in pituitary (suppress FSH & LH)
- Eunuchs (no testicles) neither get gout or grow bald (testosterone produced in testes)
 Demetrius of Apamea
- Diabetes: pathological thirst & illness in which everything that is drunk is immediately
passed as urine
 Charles Edward Brown-Sequard
- Additions of tissue extracts to people (testosterone): inhibit aging
- Founder of modern organ therapy
- Stressed role of sex hormones
 Ernest Henry Starling
- Defines (gland) organs to produce messenger molecules: hormones
- Identified hormone secretin
 20th century
- Better methods for separation & determination of hormone levels
- Isolation & purification of hormones (insulin)
- Identification chemical structure + synthesis
- In vivo effects (in living organism), bioassays
- Microscopical techniques (LM, EM)
- RIA (Yalow)
- Insulin from Langerhans islets; extracts
- Identification aa sequence
 Relations between endocrinology & behaviour from more recent date (before; more focus on
endocrinology as science)




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CL2: Endocrine System (ch2)
Why do we need endocrine system? => communication

1. Direct via cell-to-cell contact (gap-junctions)
- Ions & small molecules
1. Messenger molecules (hormones)
- Endocrine
2. Transport medium (e.g. interstitium, blood,
cell)
- Paracrine
3. Distance variable
- E.g. interspecific between individuals by
pheromones




Be able to explain and interpret regulatory
mechanisms underlying hormone- and behaviour
interactions




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 Simple (endocrine) regulation by: stimulus-secretion coupling
- Stimulating gland: risk of over-stimulation -> not desired
 Complex (endocrine) regulation) by: feedback mechanisms
- Most of the times: - feedback




Be able to
interpret how the hypothalamus and
pituitary regulate the function of the endocrine organs and vice versa by designing an experiment

 Hypothalamic-pituitary-peripheral axis
- Important to predict behaviour: how is release of hormones regulated? Which processes
are activated? What are the consequences for behaviour
 Pituitary (located just outside brain)
- Posterior pituitary = neurohypophysis release of neurohormones from hypothalamus
- Anterior pituitary = adenohypophysis, pars intermedia &
pars tuburalis directed by hypothalamus (+ & -) & feedback
systems
- Neurohormones: OT & VP/ADH -> released to blood: can act
as neurotransmitter & hormones
(Neurotransmitter: released in brain)
 Adenohypophysis
1. Releasing & inhibiting hormones from hypothalamic
capillaries
2. Portal system; vascular link between hypothalamus & adeno
3. Branching anterior pit capillaries
4. Hypothalamic hormones affect anterior pit cells
5. Release of anterior pit hormones




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6. Anterior pit capillaries re-join from vein

CRH = corticotropin
releasing hormone

GHRH = growth hormone
releasing hormone

GHIH = growth hormone
inhibiting hormone
(=somatostatin/SOM)

GnRH = gonadotropin
releasing hormone




 Prolactin (PRL)
- Dopamine (DA) inhibits release
TRH (=PRH) stimulates release
- No 3rd hormone!
- Not constant (higher levels during night) => pulsatile & nocturnal
- Effects: growth mammary gland & milk prod in mammals during lactation
(mammogenesis, lactogenesis, galactopoiesis)
- Behavioural effects: parental behaviour (also in males), migration, skin shedding)
- Too high levels -> inhibiting of FSH & LH -> natural birth control?
- Also plays role in: osmoregulation & skin pigmentation in fish
 Growth hormone (GH)
- GHIH (=SOM) inhibits
GHRH stimulates
- 3rd hormone: insulin like growth factors (IGF; not always present)
- Pulsatile & nocturnal
- Direct effects:
 Liver: protein synthesis, IGF, gluconeogenesis
 Adipose tissue: fat degradation, - glucose uptake
 Muscle: protein synthesis, - glucose uptake
- Too high levels -> gigantism (puberty) or acromegaly (adult)
 Neurohypophysis
1. Neurons in hypothalamus produce vasopressin (VP/ADH) &
oxytocin (OT) -> polar nona-peptides
2. Axons transport hormones into posterior pit
3. ADH & OT stores & released from axon terminals to blood
vessels in neurohypo (not produced by posterior pit!)
 VP/ADH
- Effect: learning & memory, increase water permeability
(retention)
- Stimulated by: increased osmotic value blood, decrease in
blood volume & pressure
 OT




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