Behavioural and neurochemical effects of intracerebroventricular administrations of p-octopamine in rats.

Intracerebroventricular administration of p-octopamine (250 micrograms) had opposite effects on locomotor activity of rats depending on whether or not the animals were submitted to electric shocks in the experimental situation. When rats were not shocked, their locomotor activity was significantly decreased by the injection. On the other hand, when rats were trained in a shuttle-box, administration of p-octopamine significantly increased avoidance responding and intertrial crossings. The neurochemical effects of the injections were relatively specific: they significantly increased p-octopamine levels in hypothalamus and brainstem but little effect was observed on noradrenaline and dopamine brain contents. These data suggest that octopamine may play the role of a neuromodulator in the central nervous system of mammals.