Intrahypothalamic and intrastriatal dopamine and norepinephrine injections in relation to motor hyperactivity in rats

High doses of dopamine (59 g) and norepinephrine (65 g) injected directly into the striatum and hypothalamus induced motor hyperactivity in rats. The motor activity recorded on the Animex for a period of 60 min after injection of 65 g of norepinephrine into the hypothalamus, showed a significant increase (p<0.005) in comparison with the controls. The increase in motor activity after dopamine (intrahypothalamic) and norepinephrine and dopamine (intrastriatal) was distinctly lower, although there was an initial large increase of motor activity after intrastriatally injected dopamine. Pre-treatment with reserpine or parachlorophenylalanine (intraperitoneal injection) to lower the serotonin level in the brain, followed by intracerebral injection of norepinephrine or dopamine failed to produce fighting or mounting behaviour.