Interactions between contact and chemosensory mechanisms in pain modulation in 10-day-old rats

Behav Neurosci. 1997 Feb;111(1):147-54. doi: 10.1037//0735-7044.111.1.147.


Antinociception was evaluated in 10-day-old rats while suckling or in contact with the mother. Testing occurred during, immediately after, or at 30 and 60 s following milk-induced hyperextension. Hyperextension-induced hypoalgesia terminated immediately with stretch cessation. For suckling rats, baseline escape levels were reacheived within 1 min. For contact rats, baseline levels were also manifest at 30 s but were elevated by 1 min. Sublingual infusions into the anterior portion of the mouth in rats that were either suckling or in contact caused a 20-25-s increase in escape latencies. For suckling rats, escape latencies returned to baseline levels immediately at infusion termination. For contact rats, latencies continued to be elevated for at least 5 min postinfusion. Thus, 3 classes of mother-infant interactions, contact, suckling, and hyperextension during milk letdown, cause varying degrees of hypoalgesia in 10-day-old rats.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Arousal / physiology
  • Attention / physiology*
  • Chemoreceptor Cells / physiology*
  • Escape Reaction / physiology
  • Female
  • Male
  • Mechanoreceptors / physiology
  • Nociceptors / physiology
  • Opioid Peptides / physiology
  • Pain Threshold / physiology*
  • Rats
  • Reaction Time / physiology
  • Sucking Behavior / physiology*
  • Touch / physiology*


  • Opioid Peptides