Classical conditioning in the fetal rat: reinforcing properties of dynorphin A (1-13).
This study examined the reinforcing properties of dynorphin A (1-13) in a single-trial classical conditioning paradigm in the E20 rat fetus. Injection of dynorphin into the cisterna magna increased fetal motor activity and reduced facial wiping in a test of perioral cutaneous responsiveness. Dynorphin was effective as an unconditioned stimulus (US) in a classical conditioning paradigm using an artificial nipple conditioned stimulus (CS) and dynorphin A (1-13) US. The association between CS and US was dependent on activity in the kappa opioid system. Re-exposure to the artificial nipple CS after a single pairing of the nipple with dynorphin resulted in conditioned activation of the kappa opioid system. Dynorphin A (1-13) functions as a reinforcer for classical conditioning in the rat fetus after intracisternal or intrahemispheric injection, with the conditioned response depending on route of administration and site of injection.
Varlinskaya
E I
EI
Pavlovian Physiological Department, Institute for Experimental Medicine, Russian Academy of Medical Sciences, St. Petersburg, Russia.
Petrov
E S
ES
Smotherman
W P
WP
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects; D001143:Arousal / Q000187:drug effects*; D001245:Association Learning / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000196:embryology; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004399:Dynorphins / Q000494:pharmacology*; D005260:Female; D005324:Fetal Movement / Q000187:drug effects*; D005865:Gestational Age; D009042:Motivation; D009294:Narcotics / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D017473:Receptors, Opioid, kappa / Q000187:drug effects; D013391:Sucking Behavior / Q000187:drug effects*
D009294:Narcotics; D010446:Peptide Fragments; D017473:Receptors, Opioid, kappa; C026843:dynorphin (1-13); D004399:Dynorphins