Chronic restraint stress does not sensitize a muscarinic mechanism

Describing the neurobiological changes which may explain the link between chronic stressors and the epidemiological association of recurrent episodes of depression in patients with unipolar or bipolar illness is a goal of psychiatric research. Disorders of mood may involve hyperactivity of central muscarinic mechanisms. Chronic forced swim stress and footshock produce supersensitivity to a muscarinic agonist. Chronic prolonged restraint is a severe stressor for the rat and activates the hypothalamic-pituitary-adrenal (HPA) axis. This report presents data suggesting that this stressor does not, unlike forced swim stress and footshock, enhance sensitivity to the hypothermic effects of a muscarinic agonist.