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A comparative analysis shows morphofunctional differences between the rat and mouse melanin-concentrating hormone systems.

Croizier S, Franchi-Bernard G, Colard C, Poncet F, La Roche A, Risold PY - PLoS ONE (2010)

Bottom Line: Sub-populations of neurons producing melanin-concentrating hormone (MCH) are characterized by distinct projection patterns, birthdates and CART/NK3 expression in rat.Evidence for such sub-populations has not been reported in other species.Furthermore, divergences in the distribution of MCH axons were observed, in particular in the ventromedial hypothalamus.

View Article: PubMed Central - PubMed

Affiliation: Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France.

ABSTRACT
Sub-populations of neurons producing melanin-concentrating hormone (MCH) are characterized by distinct projection patterns, birthdates and CART/NK3 expression in rat. Evidence for such sub-populations has not been reported in other species. However, given that genetically engineered mouse lines are now commonly used as experimental models, a better characterization of the anatomy and morphofunctionnal organization of MCH system in this species is then necessary. Combining multiple immunohistochemistry experiments with in situ hybridization, tract tracing or BrdU injections, evidence supporting the hypothesis that rat and mouse MCH systems are not identical was obtained: sub-populations of MCH neurons also exist in mouse, but their relative abundance is different. Furthermore, divergences in the distribution of MCH axons were observed, in particular in the ventromedial hypothalamus. These differences suggest that rat and mouse MCH neurons are differentially involved in anatomical networks that control feeding and the sleep/wake cycle.

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Origin of MCH projections in the mouse cortex.(A) Photomicrograph illustrating a true blue (TB) injection site in the mouse medial cerebral cortex. (B–J) Photomicrographs showing NEI/CART labeled neurons containing true blue (arrowheads) or neurons containing both NEI and true blue but not CART (arrows). Triple labeled cells were abundant in the zona incerta (ZI) and medial perifornical regions (Pfx), while double labeled cells were mostly found in the lateral hypothalamic area (LHA). The schem in K shows the localization of the three regions and a schematic distribution of NEI/CART and NEI positive/CART negative neurons represented by green and red dots respectively. fx: fornix, V3: third ventricle.
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pone-0015471-g003: Origin of MCH projections in the mouse cortex.(A) Photomicrograph illustrating a true blue (TB) injection site in the mouse medial cerebral cortex. (B–J) Photomicrographs showing NEI/CART labeled neurons containing true blue (arrowheads) or neurons containing both NEI and true blue but not CART (arrows). Triple labeled cells were abundant in the zona incerta (ZI) and medial perifornical regions (Pfx), while double labeled cells were mostly found in the lateral hypothalamic area (LHA). The schem in K shows the localization of the three regions and a schematic distribution of NEI/CART and NEI positive/CART negative neurons represented by green and red dots respectively. fx: fornix, V3: third ventricle.

Mentions: 80% of cortically projecting MCH neurons expressed CART in rat [13]. A retrograde tract tracing experiment was conducted to verify that MCH/CART neurons project in the cerebral cortex in mouse as well. True blue was injected in the dorso-medial cortex (dorsal cingulate/motor fields) of three mice (Figure 3). As expected, many retrogradely labeled neurons were found in the lateral hypothalamus and zona incerta. Using dual immunohistochemistry staining on these sections, we found that 60% of retrogradely labeled MCH neurons expressed CART (Table 2). Then, the MCH/CART sub-population takes a larger part of the whole of MCH cortical projections: these neurons represent only 44.5% of the population but 60% of cortically projecting MCH cells. However, the MCH-only cortical projection is not marginal and the balance of MCH (40%) vs MCH/CART (60%) cortical inputs is more equilibrated in mouse than in rat (20% and 80% respectively). Observation of MCH and CART expression in cortical axons corroborated this result (not illustrated). MCH axons not labeled by the CART antibodies were abundant, while in rat these axons are rare. Furthermore, many CART axons not labeled by MCH- or NEI-AS were observed in mouse. In rat cerebral cortex, CART-positive/MCH-negative axons were very rare [see 10], suggesting an additional origin for the innervations by CART axons in mouse cerebral cortex.


A comparative analysis shows morphofunctional differences between the rat and mouse melanin-concentrating hormone systems.

Croizier S, Franchi-Bernard G, Colard C, Poncet F, La Roche A, Risold PY - PLoS ONE (2010)

Origin of MCH projections in the mouse cortex.(A) Photomicrograph illustrating a true blue (TB) injection site in the mouse medial cerebral cortex. (B–J) Photomicrographs showing NEI/CART labeled neurons containing true blue (arrowheads) or neurons containing both NEI and true blue but not CART (arrows). Triple labeled cells were abundant in the zona incerta (ZI) and medial perifornical regions (Pfx), while double labeled cells were mostly found in the lateral hypothalamic area (LHA). The schem in K shows the localization of the three regions and a schematic distribution of NEI/CART and NEI positive/CART negative neurons represented by green and red dots respectively. fx: fornix, V3: third ventricle.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2984507&req=5

pone-0015471-g003: Origin of MCH projections in the mouse cortex.(A) Photomicrograph illustrating a true blue (TB) injection site in the mouse medial cerebral cortex. (B–J) Photomicrographs showing NEI/CART labeled neurons containing true blue (arrowheads) or neurons containing both NEI and true blue but not CART (arrows). Triple labeled cells were abundant in the zona incerta (ZI) and medial perifornical regions (Pfx), while double labeled cells were mostly found in the lateral hypothalamic area (LHA). The schem in K shows the localization of the three regions and a schematic distribution of NEI/CART and NEI positive/CART negative neurons represented by green and red dots respectively. fx: fornix, V3: third ventricle.
Mentions: 80% of cortically projecting MCH neurons expressed CART in rat [13]. A retrograde tract tracing experiment was conducted to verify that MCH/CART neurons project in the cerebral cortex in mouse as well. True blue was injected in the dorso-medial cortex (dorsal cingulate/motor fields) of three mice (Figure 3). As expected, many retrogradely labeled neurons were found in the lateral hypothalamus and zona incerta. Using dual immunohistochemistry staining on these sections, we found that 60% of retrogradely labeled MCH neurons expressed CART (Table 2). Then, the MCH/CART sub-population takes a larger part of the whole of MCH cortical projections: these neurons represent only 44.5% of the population but 60% of cortically projecting MCH cells. However, the MCH-only cortical projection is not marginal and the balance of MCH (40%) vs MCH/CART (60%) cortical inputs is more equilibrated in mouse than in rat (20% and 80% respectively). Observation of MCH and CART expression in cortical axons corroborated this result (not illustrated). MCH axons not labeled by the CART antibodies were abundant, while in rat these axons are rare. Furthermore, many CART axons not labeled by MCH- or NEI-AS were observed in mouse. In rat cerebral cortex, CART-positive/MCH-negative axons were very rare [see 10], suggesting an additional origin for the innervations by CART axons in mouse cerebral cortex.

Bottom Line: Sub-populations of neurons producing melanin-concentrating hormone (MCH) are characterized by distinct projection patterns, birthdates and CART/NK3 expression in rat.Evidence for such sub-populations has not been reported in other species.Furthermore, divergences in the distribution of MCH axons were observed, in particular in the ventromedial hypothalamus.

View Article: PubMed Central - PubMed

Affiliation: Faculté de Médecine et de Pharmacie, Université de Franche-Comté, Besançon, France.

ABSTRACT
Sub-populations of neurons producing melanin-concentrating hormone (MCH) are characterized by distinct projection patterns, birthdates and CART/NK3 expression in rat. Evidence for such sub-populations has not been reported in other species. However, given that genetically engineered mouse lines are now commonly used as experimental models, a better characterization of the anatomy and morphofunctionnal organization of MCH system in this species is then necessary. Combining multiple immunohistochemistry experiments with in situ hybridization, tract tracing or BrdU injections, evidence supporting the hypothesis that rat and mouse MCH systems are not identical was obtained: sub-populations of MCH neurons also exist in mouse, but their relative abundance is different. Furthermore, divergences in the distribution of MCH axons were observed, in particular in the ventromedial hypothalamus. These differences suggest that rat and mouse MCH neurons are differentially involved in anatomical networks that control feeding and the sleep/wake cycle.

Show MeSH
Related in: MedlinePlus