Opioid mediation of amniotic fluid effects on chemosensory responsiveness in the neonatal rat

Valerie Mendez-Gallardo, Scott R. Robinson

Research output: Contribution to journalArticle

7 Scopus citations


The present study investigated if oral exposure to milk or amniotic fluid (AF) alters responsiveness to sensory stimulation in the neonatal rat, and whether these effects are mediated by the opioid system. Facial wiping evoked by intraoral lemon infusion was used as a measure of sensory responsiveness. Pups were tested in a supine posture, because they showed more paw-face strokes during facial wiping than pups tested prone (Experiment 1). Moreover, pups orally exposed to milk (Experiment 2) or AF (Experiment 3) showed a diminished wiping response to lemon compared to controls exposed to water. Blockade of opioid receptors with the nonselective antagonist naltrexone (Experiment 4) or the kappa antagonist nor-binaltorphimine (Experiment 5) reinstated higher levels of facial wiping after AF exposure. These findings confirm developmental continuity between fetal and neonatal behavioral responses to AF and the ability of AF to induce activity at kappa receptors of the endogenous opioid system.

Original languageEnglish (US)
Pages (from-to)740-754
Number of pages15
JournalDevelopmental psychobiology
Issue number8
Publication statusPublished - Dec 1 2010


All Science Journal Classification (ASJC) codes

  • Developmental and Educational Psychology
  • Developmental Neuroscience
  • Developmental Biology
  • Behavioral Neuroscience

Cite this