Chapter 6 Dwarfism and the Importance of Mothers

I. Growth doesn’t come cheap.

A. Calcium à bones; amino acids à proteins, including muscle; fatty acids à cell walls; glucose pays

for the building costs.

B. Growth hormone: Breaks down fat cells to release fatty acids to be used for growing cells. Also enhances protein synthesis. GH is important for wound healing as well as growth.

C. Somatomedins: Produced in the liver and other peripheral tissues in response to GH. Increase cell division and maturation of numerous kinds of cells. Work synergistically with GH.

D. Thyroid hormone: Promotes growth hormone release; increase responsiveness of bones to

somatomedins.

E. Insulin: Increases transport of amino acids and glucose into cells.

F. Estrogen: Promotes growth of long bones, by acting on bone and by increasing growth hormone (GH)

secretion.

G. Testosterone: Acts similarly to estrogen and also enhances muscle growth. Also speeds cessation of

bone growth by maturing ends of bones.

II. Control of GH

A. GHRH is secreted in bursts from neurons in the mediobasal hypothalamus, especially the arcuate

nucleus. It is released in the median eminence into the portal system that goes to the anterior pituitary,

which in turn releases GH into the systemic circulation. GHRH also increases synthesis of GH.

1. GH is released almost exclusively during the deep slow-wave sleep early in the night. Elderly

people have little deep slow wave sleep and little GH, which results in poor wound healing.

2. Other neurons around the arcuate send axons to other areas of the hypothalamus to

increase feeding.

B. Somatostatin (GHIH) neurons are in anterior hypothalamus and send axons both to the median

eminence and to GHRH neurons in the arcuate nucleus.

1. They inhibit both synthesis and release of GHRH (in arcuate neurons) or GH (via the portal

system to the anterior pituitary).

2. Somatostatin also decreases intestinal absorption and decreases insulin secretion.

C. Anterior pituitary: GH-secreting cells (somatotrophs) are the most numerous type of cell (30-40% in

males and 20-30% in females).

1. GH is highest immediately before and after birth. It’s also important for adolescent growth spurt.

III. Growth inhibition during stress

A. Stress dwarfism, psychosocial dwarfism, or psychogenic dwarfism: extremely rare. Products of vast,

grotesque family psychopathology. Overcome by “parentectomy.”

B. King Frederick II of Sicily: Language experiment: none of the kids survived.

C. Lauren Belfer (City of Light): Almost no infants survived in orphanages at turn of century.

D. Children in 2 orphanages after WW II. Fraulein Grun vs. Fraulein Schwarz.

E. 1900s -1930s: Child rearing “intensely Spartan”: “vicious practice” of picking up a child when it cried.

F. Peter Pan

III. The mechanisms underlying stress dwarfism

A. Hormones: Hypothalamus: GHRH (growth hormone releasing hormone) vs. somatostatin (or GHIH,

growth hormone inhibiting hormone) sent to anterior pituitary. Growth problems in kids over 3 are

mostly due to decreased GH and related problems.

1. Probably main problem is too much GHIH.

2. Or pituitary is too sensitive to GHIH or insensitive to GHRH.

3. Somatomedins + GH bind to receptors on cells à grow and divide. Psychogenic dwarfism: cells

become insensitive to GH and somatomedins.

4. Ornithine decarboxylase (ODC): critical for cell division and growth. Maternal deprivation à

decreased levels of GH and ODC.

5. Also sympathetic N.S. overactivity à blocks growth hormone secretion.

6. Glucocorticoids: Block GH secretion; decrease sensitivity to GH; decrease synthesis of new

proteins and DNA.

a. Hormone levels 2 to 3 X normal disrupt growth.

b. Major stressors increase hormone levels up to 10 X.

B. Gastrointestinal problems

1. Increased Symp. N.S. activity decreases digestion.

2. Affects primarily infants.

C. The need for active touch

1. Rats: Anesthetized mother doesn’t increase GH; mimicking active stroking does.

2. Humans: Tiffany Field: 15 min periods 3/day, stroking, moving limbs of premature babies: kids

grew 50% faster, were more active and alert, matured faster, released from hospital 1 wk. earlier.

Could save $1billion/year and produce healthier kids for years after.

3. Sometimes a stressor is the absence of a needed stimulus.

IV. Growth and growth hormone in adults (Why do adults secrete GH?)

A. Remodeling bone (along with somatomedins, parathyroid hormone, and vitamin D.

1. Bone is “Federal Reserve” of body’s calcium.

B. Glucocorticoids: counteracts effects of GH. In large quantities (as in Cushing’s syndrome or treatment

of leukemia, etc.) they can produce osteoporosis. Chronic stress may damage bone.

V. Stress and growth hormone secretion in humans

A. Immediately after stress onset, GH levels rise. This helps to remove nutrients from storage sites for

new construction.

B. But if somatomedin is blocked by glucocorticoids, the nutrients are available for the current

emergency. However, somatomedin is not completely blocked, so GH needs to be shut down after a while, so it does not start a new, expensive growth project.

C. Tom Landauer & John Whiting: Stressful rites of passage. Compared those from same gene pool that

did or did not have stressful rituals. If stressor occurred in first 2 years, growth was stimulated; from

2-6 yrs, no effect; 6-15 yrs, growth was inhibited. Couldn’t completely rule out effects of diet or

killing off the weakest babies.

VI. The “L” word

A. Harlow took on behaviorism: not “reinforcement” that’s important.

B. Did his experiments go too far?