lect 1 endocrine

• Neuroendocrinology


  The study of the interaction between the nervous system and the endocrine system
• PHSL 231 Neuroendocrinology


  • 6 lectures
  • Lecture 1: The hypothalamus and pituitary gland
  • Lecture 2: Stress and the adrenal glands
  • Lecture 3-4: Glucose metabolism, energy balance and obesity
  • Lecture 5: Hypothalamic regulation of reproductive function
  • Lecture 6: Review and integration
• Endocrinology


  The study of hormones, their receptors and their intracellular signalling pathways

  
• Hormones


  Chemical messengers produced in one location and transported to a second location (target cells) where they exert their effects, often via the bloodstream, acting at low concentrations

  
• Principal functions of the endocrine system

  • Maintain homeostasis
  • Regulate growth and development
  • Control energy storage and use
  • Mediate the body's response to environmental cues
• Chemical classification of hormones

  • Peptides
  • Proteins
  • Amines
  • Steroids
  • Prostaglandins
• Hormones can reach all organ systems
• Hormones can have synergistic effects
• Important endocrine glands


  • Hypothalamus
  • Pineal gland
  • Pituitary
  • Thyroid
  • Parathyroid
  • Adrenal gland
  • Kidney
  • Ovaries
  • Testes

  
• Organs can contain endocrine cells (e.g. heart, liver, stomach, kidney, intestine)
• Melatonin


  The hormone of the darkness, released by the pineal gland and acting as a Zeitgeber ("time-giver") signal
• Hypothalamus and pituitary gland

  • Control water balance
  • Control metabolism
  • Control body growth
  • Control reproduction
  • Control milk secretion
• Hypothalamic control of anterior pituitary hormone secretion

  1. Hypothalamus releases hypophysiotrophic hormones (CRH, TRH, GnRH, GHRH, SS, DA)

  2. Anterior pituitary releases hormones (ACTH, TSH, LH/FSH, GH, PRL)

  3. Endocrine glands release hormones

  4. Feedback loops

  
• Growth hormone (GH, somatotrophin)


  Stimulates postnatal growth and development, metabolism, body composition
• Control of growth hormone secretion

  1. GHRH neurons stimulate GH release

  2. Somatostatin neurons inhibit GH release

  3. GH stimulates IGF-1 release from liver

  4. IGF-1 inhibits GH release (negative feedback)

  
• Effects of growth hormone

  • Stimulates growth of bones, muscles and other tissues via IGF-1
  • Stimulates protein synthesis
  • Increases blood glucose
  • Increases triglyceride breakdown and free fatty acid mobilization
• Growth hormone secretion is pulsatile and follows a diurnal pattern

  
• Giganticism is a result of excess GH production
• Posterior pituitary gland


  Secretes vasopressin (anti-diuretic hormone) and oxytocin

  
• Vasopressin


  • Secreted in response to increased plasma osmotic pressure or decreased blood volume
  • Inhibits urine production (diuresis) in the kidney
  • Causes blood vessel contraction (vasoconstriction)

  
• Oxytocin


  • Acts upon the kidney to promote sodium excretion
  • Increases release of atrial natruiretic factor from the heart
  • Contracts mammary ducts for milk let-down during suckling
  • Causes uterine contraction during delivery
• Diabetes insipidus is caused by impaired or absent secretion of vasopressin