Serotonergic neuron of the dorsal and medial raphe nuclei (DRN/MRN serotonergic neurons)

The serotonergic neurons of the dorsal and medial raphe nuclei represent the primary source of serotonin (5-HT) for the forebrain and midbrain, playing a critical role in the central nervous system's neuromodulatory network [1, 3, 6]. These neurons are located in the brainstem and project extensively to regions such as the prefrontal cortex, amygdala, and hippocampus, where they regulate mood, sleep-wake cycles, appetite, and cognitive processes [2, 4, 14]. While often discussed as a unified system, the dorsal raphe nucleus (DRN) and median raphe nucleus (MRN) exhibit distinct anatomical projections and electrophysiological properties; the DRN is typically linked to stress and mood, while the MRN is associated with hippocampal rhythms and memory [5, 11]. Dysregulation of this neuronal system is a hallmark of major depressive disorder, anxiety, and other psychiatric conditions, making the molecular components within these neurons—such as the serotonin transporter (SERT) and 5-HT1A autoreceptors—key therapeutic targets [4, 7, 16]. Pharmacological intervention typically involves selective serotonin reuptake inhibitors (SSRIs) and other agents that modify 5-HT levels or receptor activity, although therapeutic effects often require chronic administration to allow for neuroplastic changes and autoreceptor desensitization [4, 16, 20].

Other names

Dorsal raphe nucleus (DRN) serotonergic neuronsMedian raphe nucleus (MRN) serotonergic neuronsB7 and B8 serotonergic cell groupsRostral raphe serotonergic systemMidbrain raphe serotonergic neurons

Drugs primarily modulate these neurons by inhibiting the serotonin transporter (SERT) to increase synaptic 5-HT concentrations, activating or antagonizing somatodendritic 5-HT1A autoreceptors to modulate neuronal firing rates, or inhibiting monoamine oxidase (MAO) to prevent intracellular serotonin degradation [1, 4, 10, 16].