Ketamine blocks a taste-mediated conditioned motor response in perinatal rats.
Brain N-methyl-D-aspartate (NMDA) glutamate receptors have been implicated as important mediators of both learning and neuronal development. The current study investigated how ketamine HCl (a well-known NMDA-receptor blocking drug) would influence taste-mediated conditioned motor responses in perinatal rats. Dams pregnant with E19 rat fetuses were injected with 0, 50, or 100 mg/kg ketamine HCl (IP). One-half hour later, a reversible spinal block was performed on the dam, and fetuses received an oral injection of 10 microl 0.3% Saccharin (SAC) or water while in utero. After the oral injection, fetuses received either saline or LiCl (81 mg/kg, IP). The uterus was replaced and, 2 days later (E21), rats received oral lavage with SAC. Rats in other litters were born via a normal vaginal delivery and were exposed to SAC on postnatal day 3 (P3). Observations of motor responses were recorded immediately after the oral lavage of SAC. If SAC had been paired with LiCl in utero, both E21 and P3 pups exhibited a conditioned suppression of orofacial movements (compared to controls). Both doses of ketamine significantly attenuated this taste-mediated conditioned motor response. These data reinforce the current conception of the fetus and neonate as sophisticated sensors and responders to the uterine and extrauterine environment. Further, our findings indicate a role for NMDA receptors in the formation of a conditioned motor response in fetal rats.
Mickley
G A
GA
Department of Psychology, Carnegie Hall, Baldwin-Wallace College, 275 Eastland Rd., Berea, OH 44017-2088, USA.
Remmers-Roeber
D R
DR
Crouse
C
C
Peluso
R
R
D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000187:drug effects / Q000502:physiology; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D013649:Taste / Q000187:drug effects*
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine