Development of serotonergic neurons of dorsal raphe nuclei in mice with knockout of monoamine oxidase a and 5-HT1A and 5-HT1B autoreceptor

The morphological changes in the development of serotonergic neurons of the dorsal raphe nuclei in the medulla oblongata was studied by immunocytochemistry in mice with knockout of 1A and 1B serotonin autoreceptors as well as monoamine oxidase A. Serotonin autoreceptors regulate electric activity of serotonergic neurons as well as the synthesis and release of the neurotransmitter, while monoamine oxidase A catalyzes its degradation. These genetic modifications proved to have no effect on the number of serotonergic neurons in the medulla oblongata but induced morphofunctional changes. Decreased cell size and increased intracellular serotonin level were observed in the case of monoamine oxidase A deficiency, while excessive cell size and decreased intracellular serotonin level were observed in the case of autoreceptor deficiency. The data obtained confirm the hypothesis of autoregulation of serotonergic neurons in development.