Intracerebroventricular apomorphine alleviates spontaneous forgetting and increases cortical noradrenaline

Rats were trained in a 6 unit spatial discrimination maze for food reinforcement; they were then implanted with intracerebroventricular (i.c.v.) cannulae and tested 25 days after training. Control animals displayed significant forgetting; 10 micrograms apomorphine alleviated this forgetting, while a higher dose did not. A hole board activity study revealed that i.c.v. Apomorphine does not produce the shaped dose-response activity curve found with systemic injections. Neurochemical analysis of forebrain structures after injections showed that the dose which facilitated memory retrieval also increased cortical and hippocampal noradrenaline, while the larger dose did not.