Hormones, the Brain, and Behavior

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Hormones, the Brain, and Behavior
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Types of Chemical Communication

• Synaptic (neurotransmitters)

• ENDOCRINE (hormones)
• Released in bloodstream
• act at distance (target organs)
• Slow action

Other types of communication Exocrine,
Pheromone Some substances (e.g., adrenaline) act
both as NT and hormone
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Glands of the Endocrine System
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The HPA Axis the key system controlling stress
response
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(CRH)
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Glucocorticoidsi.e. cortisol
Target organs
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Glucocorticoids (stress)

• Short term effect
• Mobilize energy stores
• Long term effect
• Hippocampal cell death

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How are hormones controlled?

• The hypothalamus controls the pituitary gland
• The pituitary has two major divisions
• Anterior (aka hypophysis). Its connected to the
  hypothalamus via blood vessels and is controlled
  by hormones released from the hypothalamus.
• Posterior. Hypothalamic neurons project axons
  that secrete oxytocin (and vasopressin) into
  capillaries of the posterior pituitary.

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• Hormone release affects behavior
• Estrogens (ovaries) ?female sexual behavior.
• Androgens (testes) ?male sexual behavior.
• Insulin (pancreas) ?food intake.
• Epinephrine (adrenal) ?arousal and alertness.
• Oxytocin (posterior pituitary) ?parental
  behavior.

• and behavior can affect hormone release
• Fear or surprise ?epinephrine
• Smell of food ?insulin secretion
• Nipple stimulation or crying baby ?oxytocin
  release and milk letdown.
• Sexual intimacy ?oxytocin, among others

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Endocrine manipulations are quite common in our
society and have a long history.

• Castration of male animals Why do it?
• Its easy!
• Positive effects on behavior
• May improve physical properties
• Population control
• We dont need a whole bunch of males anyway!!

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Actually, theres a long history of castrating
men eunuchs

• Punishment
• Testosterone-sensitive jobs guarding the
  harem
• Castrati male sopranos until late 1700s
• Over a million eunuchs in contemporary India
  mostly by choice.

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The first experimental endocrinology was
done by A.A. Berthoud 1840s

• Caponization of roosters
• Normal males red comb, colorful plumage,
  struts, fights, mates, and crows
• Castrated before maturity no comb, no strut, no
  fight, no crow, no mates
• Castrated before maturity and testes implanted
  into abdomen just like normals!