Automatic registration of behaviour related to dopamine and noradrenaline transmission

In a search for behavioural tests where certain behaviours related to dopamine and noradrenaline transmission can be recorded automatically we have developed and tested an automatic version of the hole board. The test measures two behaviour variables: the open field variable defined as the number of interruptions of photocell beams symmetrically covering an open field area and the 'hole' variable, defined as the number of head-dips into holes recorded by photocell beams positioned underneath the floor of the cage. The method was evaluated by observations of the rats concomitant with the automatic registrations. The animals were tested on dopamine agonistic drugs, which were found to decrease the 'hole' counts and cause an increase in the open field counts as compared to saline injected controls. d-Amphetamine which is known to increase the release of dopamine as well as of noradrenaline caused an increase in both the open field counts and the 'hole' counts. The increase in 'hole' counts caused by d-amphetamine was reduced when the animals were pretreated with a dopamine-beta-hydroxylase inhibitor (FLA 63) or a noradrenaline receptor blocker (phenoxybenzamine). These results suggests that the increase in the 'hole' variable was related to an increased noradrenaline transmission while the increase in the open field variable was related to an increased dopamine transmission. The lowest dose of apomorphine caused a behavioural inhibition which may be explained by a preferential stimulation of dopamine autoreceptors.