Septal dopaminergic–cholinergic interactions during stress

To find out whether or not modification of the dopaminergic tone affects the stress response of the septo-hippocampal cholinergic system, rats were treated with DA-2 receptor agonist or antagonist. The findings indicate that after treatment with the DA antagonist sulpiride, when the septo-hippocampal cholinergic system is released from tonic dopaminergic inhibition, it becomes activated to a certain level and cannot be further activated in response to acute stress. Enhancement of the dopaminergic tone, by treatment with the DA agonist apomorphine, may suppress the activation of the cholinergic system in response to acute stress. Thus, when stressful conditions are encountered, the initial transient activation of the septo-hippocampal cholinergic system, which subsides within minutes, may be temporally related to a slower stress-induced activation of the mesoseptal dopaminergic system. These results imply that septo-hippocampal cholinergic activity represents an active pathway for major dopaminergic neuronal signals of stress.