Changes in rat hippocampal benzodiazepine receptors and lack of changes in muscarinic receptors after fimbria-fornix lesions.

The binding of [3H] L-quinuclidinylbenzilate to muscarinic receptors and [3H] flunitrazepam to benzodiazepine receptors were studied in the rat hippocampus after lesion of the fimbria-fornix. While the muscarinic receptors showed no change, the benzodiazepine receptors did change considerably at various time intervals. Two days after the lesion the specific [3H] flunitrazepam binding decreased 38%, while at 5 days it increased 65%. After 14 days of the lesion it still was significantly above normal. These changes are due to a variation in the number of sites, and not in affinity. Possible interpretations of these results are discussed.