Effects of intrahypothalamic injections of kainic acid on the behaviour of rats.

The effects of bilateral microinjections of kainic acid 1.0 microgram and 2.5 micrograms into the hypothalamus on the behaviour of rats were studied controlling this behaviour during 2 weeks by the method of Lat. Moreover, the exploratory activity and irritability of the animals were assessed during that time period. After 2 weeks the activity of acetyltransferase and the level of GABA were determined in rat brain. Bilateral injections of kainic acid produced only slight changes in rat behaviour, no changes in the activity of acetyltransferase in the hypothalamus, but raised significantly the level of GABA in this structure and in the thalamus. The results of these investigations point out indirectly that the hypothalamus contains no greater number of cell bodies of cholinergic neurons but it may contain cholinergic and GABA-ergic axons which are not destroyed by kainic acid.