Feeding in response to site-selective antagonists of hindbrain NMDA receptors
Anson, Jamie A.
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The non-competitive NMDA receptor antagonist MK-801 increases meal size when it is injected into the caudal hindbrain, suggesting that hindbrain NMDA receptors participate in the control of food intake. NMDA receptors are not biochemically homogeneous. While all NMDA receptors are susceptible to blockade by MK-801, the NMDA antagonist, ifenprodil, binds selectively to NMDA receptors containing the NR2B subunit. NR2B containing receptors are present in the caudal hindbrain. We hypothesized that NMDA receptors containing the NR2B subunit are responsible for increased feeding following hindbrain NMDA receptor blockade. To test this hypothesis, we microinjected ifenprodil into dorsal hindbrain sites at which MK-801 previously has been shown to increase food intake. We found that rats injected with ifenprodil did not increase their food intake. These data suggest that of the NMDA receptor population in the hindbrain which responded to MK-801, those containing the NR2B subunit do not participate in increased food intake. KEYWORDS: