Blockade of peripheral beta-adrenergic receptors fails to suppress the cerebral spread of an engram in mice.

Using bitemporal injections of puromycin, we have reported observations interpreted to indicate that a systemic injection of (-)-propranolol (50 micrograms/kg) drastically suppressed the spread of an engram in mice from the hippocampalentorhinal area to widespread cerebral areas. The present experiments were made with a non-selective, irreversible beta-adrenergic receptor antagonist that fails to cross the blood-brain barrier in order to test the possibility that the propranolol-induced blockade of peripheral beta-receptors might contribute to its effect on engram spread. Prolonged blockade of peripheral receptors by the irreversible antagonist had no effect on engram spread, suggesting that propranolol's effect was centrally mediated.