Ketamine blocks a taste recognition memory in fetal rats

Area of Science:

• Neuroscience
• Developmental Biology
• Behavioral Science

Background:

• Novelty/familiarity decisions are crucial for information processing and memory formation.
• Previous studies show fetal rats (E19) can form taste recognition memory for saccharin (SAC), retained until postnatal day 3 (P3).

Purpose of the Study:

• To investigate the role of N-methyl-D-aspartate (NMDA) receptors in establishing early taste recognition memory in rats.
• To determine if NMDA receptor antagonism during fetal development affects the formation or retention of taste memory.

Main Methods:

• Pregnant rats were administered ketamine (an NMDA receptor antagonist) at varying doses.
• E19 fetuses received in utero oral administration of saccharin (SAC) or water.
• Postnatal pups were tested for taste recognition memory by oral lavage with SAC and motor responses were recorded.

Main Results:

• Control neonates exhibited significantly more perseverative mouth movements, total mouth movements, and licks when tasting familiar SAC compared to novel SAC.
• This taste recognition memory response was absent in rat pups exposed to ketamine in utero.
• NMDA receptor blockade in fetuses prevented the development of the observed taste memory response.

Conclusions:

• Early non-associative taste memories in rats may be disrupted by NMDA receptor blockade during fetal development.
• NMDA receptors play a critical role in the establishment of early taste recognition memory.
• In utero exposure to NMDA receptor antagonists can impair the development of memory systems.