INHIBITORY EFFECT OF INTRAHIPPOCAMPAL NPY INJECTION ON AMPHETAMINE-INDUCED BEHAVIORAL ACTIVITY

The aim of the present study was to investigate the influence of intra hippocampal neuropeptide Y (NPY) administration on the rats' behaviour . The CA1 field or dentate area (GD) of the dorsal hippocampus was chr onically implanted with intracerebral cannulae. NPY (or redistilled wa ter in the control group) was injected bilaterally or unilaterally in a volume of 1 mu l to each hippocampus, in a dose of 1 or 2 mu g per r at. A separate group of rats was pretreated with amphetamine (1 mg/kg, s.c.), 15 min before a bilateral microinjection of NPY (2 mu g) into the CA1 region. Immediately after the intrahippocampal injection, the rats' behaviour was tested in an open field box. It was found that NPY did not change the locomotor and the exploratory activity after eithe r CA1 or GD administration to non-pretreated animals. In amphetamine p retreated rats, NPY injected into the CA1 field inhibited the amphetam ine induced increase in sniffing and rearing and, to a lesser extent, the number of line-crossings. The obtained results may suggest an inhi bitory action of NPY in the CA1 hippocampal field on the behavioural h yperactivity.