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Updated: Mar 23, 2026
Primary Culture of Mouse Dopaminergic Neurons
Published on: September 8, 2014
Cellular architecture and transmitter phenotypes of neurons of the mouse median raphe region
Katalin E Sos1,2, Márton I Mayer1, Csaba Cserép1
1Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083, Hungary.
Abstract:
The median raphe region (MRR, which consist of MR and paramedian raphe regions) plays a crucial role in regulating cortical as well as subcortical network activity and behavior, while its malfunctioning may lead to disorders, such as schizophrenia, major depression, or anxiety. Mouse MRR neurons are classically identified on the basis of their serotonin (5-HT), vesicular glutamate transporter type 3 (VGLUT3), and gamma-aminobutyric acid (GABA) contents; however, the exact cellular composition of MRR regarding transmitter phenotypes is still unknown. Using an unbiased stereological method, we found that in the MR, 8.5 % of the neurons were 5-HT, 26 % were VGLUT3, and 12.8 % were 5-HT and VGLUT3 positive; whereas 37.2 % of the neurons were GABAergic, and 14.4 % were triple negative. In the whole MRR, 2.1 % of the neurons were 5-HT, 7 % were VGLUT3, and 3.6 % were 5-HT and VGLUT3 positive; whereas 61 % of the neurons were GABAergic. Surprisingly, 25.4 % of the neurons were triple negative and were only positive for the neuronal marker NeuN. PET-1/ePET-Cre transgenic mouse lines are widely used to specifically manipulate only 5-HT containing neurons. Interestingly, however, using the ePET-Cre transgenic mice, we found that far more VGLUT3 positive cells expressed ePET than 5-HT positive cells, and about 38 % of the ePET cells contained only VGLUT3, while more than 30 % of 5-HT cells were ePET negative. These data should facilitate the reinterpretation of PET-1/ePET related data in the literature and the identification of the functional role of a putatively new type of triple-negative neuron in the MRR.
Insights
The median raphe region
Area of Science:
- Neuroscience
- Cellular Biology
- Neurochemistry
Background:
- The median raphe region (MRR) is vital for regulating brain activity and behavior.
- MRR dysfunction is linked to psychiatric disorders like depression and anxiety.
- The precise cellular and transmitter phenotypes within the MRR remain incompletely understood.
Purpose of the Study:
- To comprehensively characterize the cellular composition of the mouse median raphe nucleus (MR) and the entire median raphe region (MRR).
- To investigate the co-expression of serotonin (5-HT), vesicular glutamate transporter type 3 (VGLUT3), and gamma-aminobutyric acid (GABA) in MRR neurons.
- To evaluate the expression of ePET in relation to 5-HT and VGLUT3 in MRR neurons using transgenic mouse models.
Main Methods:
- Unbiased stereological methods were employed to quantify neuronal populations.
- Immunohistochemistry was used to determine the expression of 5-HT, VGLUT3, GABA, and NeuN.
- ePET-Cre transgenic mice were utilized to analyze ePET expression patterns in relation to neurotransmitter markers.
Main Results:
- In the MR, 5-HT neurons constituted 8.5%, VGLUT3 neurons 26%, and GABAergic neurons 37.2%.
- A significant population of triple-negative neurons (14.4% in MR, 25.4% in MRR) expressing only NeuN was identified.
- ePET expression was found in a substantial number of VGLUT3-positive cells, with some 5-HT neurons being ePET-negative.
Conclusions:
- The study reveals a more complex cellular composition of the MRR than previously assumed, including a notable population of triple-negative neurons.
- Findings challenge the exclusive use of PET-1/ePET-Cre mice for targeting 5-HT neurons, as ePET expression does not perfectly correlate with 5-HT.
- These results necessitate a re-evaluation of studies using PET-1/ePET-Cre models and highlight the need to identify the function of novel neuronal subtypes in the MRR.
