Кое-где мелькает Ацетилхолин.

Several lines of evidence suggest that acetylcholine has a role in the etiology of depression. The administration of physostigmine, an inhibitor of cholinesterase, can exacerbate depression, and patients with depression experience exaggerated polysomnographic findings and pupillary responses following administration of cholinergic medications. These findings suggest that anticholinergic medications may improve depression, but a controlled study of the anticholinergic medication biperiden failed to demonstrate a significant benefit of therapy.

In the current study, the authors report on the efficacy of scopolamine in the management of depression and bipolar disorder. The study began as an investigation of the effect of anticholinergic treatment on cognition in depression, but the authors designed a randomized, crossover trial after noting an improvement of depression scores associated with scopolamine.

Вот почему при отравлении Амитриптилином развивается холинолитический синдром

Cholinergic Modulation of Cognition and Emotion in Mood Disorders: Functional Neuroimaging Studies (незаконченное исследование)
...
The cholinergic system mediates the release of neurotransmitters, including acetylcholine. This system may play a role in the behavioral and cognitive impairment observed in individuals with depression. Evidence suggests that during major depressive episodes, the cholinergic system is hypersensitive to acetylcholine. Agents that enhance the function of acetylcholine-binding receptors called muscarinic receptors increase depressive symptoms in depressed individuals and can produce depressive symptoms in healthy people. Muscarinic antagonists inhibit muscarinic function and may improve the behavioral and cognitive aspects of depression. This study will use functional magnetic resonance imaging (fMRI) scans of the brain to evaluate the effects of a cholinergic antagonist on performance and brain activity in people with major depression. ... >>>

...The Cholinergic System
Lower than normal levels of choline have been found in the erythrocytes of bipolar patients – prompting researchers to believe that an imbalance between cholinergic and catecholaminergic activity is important in the pathophysiology of bipolar disorder. Further evidence implicating the cholinergic system in bipolar disorder is the antimanic properties of cholinergic agonists and the modulation of manic symptoms by the cholinesterase inhibitor phygostigmine (Manji & Lenox, 2000; Muller-Oerlinghausen et al, 2002)... >>>

J Neural Transm. 1987;70(3-4):295-312.
Acetylcholine and affective disorder.
Leong SS, Brown WA.

We reviewed the evidence for involvement of central cholinergic neurons in affective disorder. Cholinomimetics inhibit speech, thought, and activity in most subjects, decrease manic symptoms and, in some affective disorder patients, produce depressive symptoms. Cholinomimetics also cause ACTH and cortisol secretion and decrease latency to REM sleep. It is unclear whether cholinomimetics are specifically "antimanic" or "depressogenic" or whether their fundamental effect is nonspecific behavioral inhibition; whether the observed effects of cholinomimetics are mediated largely through cholinergic pathways, are secondary to changes in other neurotransmitters or are part of a nonspecific stress response. The suggestion that anticholinergic agents have mood elevating properties has not yet been subjected to controlled investigation. Although the proposal that affective disorders involve cholinergic neurons has received some support from clinical investigation further research is required to substantiate the intriguing observations to date and to clarify the physiologic and psychologic processes mediating them. >>>

The Role of Acetylcholine Mechanisms in Affective Disorders
David S. Janowsky and David H. Overstreet
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It is possible that pharmacologically induced changes in acetylcholine may cause perturbations in depression-relevant systems other than the cholinergic nervous system. Pharmacologically induced acetylcholine alterations could cause a "model depression" by perturbing other potential governing neurotransmitters (for example, GABA, serotonin, dopamine, or norepineprine) or second messengers in affect disorder patients. ... и т.д. и т.п. >>>