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Efferent projections of prokineticin 2 expressing neurons in the mouse suprachiasmatic nucleus.

Zhang C, Truong KK, Zhou QY - PLoS ONE (2009)

Bottom Line: Prokineticin 2 (PK2) is one of the candidate output molecules from the SCN.Our data revealed that EGFP-expressing neurons in the SCN, hence representing some of the PK2-expressing neurons, projected to many known SCN target areas, including the ventral lateral septum, medial preoptic area, subparaventricular zone, paraventricular nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamic area and paraventricular thalamic nucleus.The efferent projections of PK2-expressing neurons supported the role of PK2 as an output molecule of the SCN.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California Irvine, Irvine, California, United States of America.

ABSTRACT
The suprachiasmatic nucleus (SCN) in the hypothalamus is the predominant circadian clock in mammals. To function as a pacemaker, the intrinsic timing signal from the SCN must be transmitted to different brain regions. Prokineticin 2 (PK2) is one of the candidate output molecules from the SCN. In this study, we investigated the efferent projections of PK2-expressing neurons in the SCN through a transgenic reporter approach. Using a bacterial artificial chromosome (BAC) transgenic mouse line, in which the enhanced green fluorescence protein (EGFP) reporter gene expression was driven by the PK2 promoter, we were able to obtain an efferent projections map from the EGFP-expressing neurons in the SCN. Our data revealed that EGFP-expressing neurons in the SCN, hence representing some of the PK2-expressing neurons, projected to many known SCN target areas, including the ventral lateral septum, medial preoptic area, subparaventricular zone, paraventricular nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamic area and paraventricular thalamic nucleus. The efferent projections of PK2-expressing neurons supported the role of PK2 as an output molecule of the SCN.

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Distribution of EGFP-immunostained fibers in the SCN target areas and complementary expression of PKR2.A–D. Digoxigenin-labeled in situ hybridization showed the expression of PKR2. Arrows indicated PKR2-positive cells. DMH, dorsomedial hypothalamic nucleus; LH, lateral hypothalamic area; LHb, lateral habenular nucleus; LSD, dorsal lateral septum; LSV, ventral lateral septum; MnPO, median optical area; PVN, paraventricular nucleus; PVT, paraventricular thalamic nucleus. Scale bar  =  200 µm. E–K. Immunofluorescence staining showed EGFP-ir fibers in E) the median preoptic area (MnPO) and ventral lateral septum (LSV); F) the subparaventricular zone (SPa) and paraventricular nucleus (PVN); G) the lateral hypothalamic area (LH), dorsomedial hypothalamic nucleus (DMH) and arcuate nucleus (Arc); H) the paraventricular thalamic nucleus (PVT); I) the bed nucleus of the stria terminalis, medial (BSTM) and LSV; J) the posterior hypothalamic area (PH) and medial supramammillary nucleus (SuMM) and K) periaqueductal gray (PAG). Scale bar  =  100 µm. L. A high magnification view of EGFP-ir cells and fibers inside the suprachiasmatic nucleus (SCN). Arrows indicated EGFP-ir fibers that extended from one nucleus into the contralateral nucleus. Scale bar  =  20 µm. 3V, third ventricle. The animals were sacrificed at ZT12. Cell nuclei were counter-stained in blue in E–L.
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pone-0007151-g002: Distribution of EGFP-immunostained fibers in the SCN target areas and complementary expression of PKR2.A–D. Digoxigenin-labeled in situ hybridization showed the expression of PKR2. Arrows indicated PKR2-positive cells. DMH, dorsomedial hypothalamic nucleus; LH, lateral hypothalamic area; LHb, lateral habenular nucleus; LSD, dorsal lateral septum; LSV, ventral lateral septum; MnPO, median optical area; PVN, paraventricular nucleus; PVT, paraventricular thalamic nucleus. Scale bar  =  200 µm. E–K. Immunofluorescence staining showed EGFP-ir fibers in E) the median preoptic area (MnPO) and ventral lateral septum (LSV); F) the subparaventricular zone (SPa) and paraventricular nucleus (PVN); G) the lateral hypothalamic area (LH), dorsomedial hypothalamic nucleus (DMH) and arcuate nucleus (Arc); H) the paraventricular thalamic nucleus (PVT); I) the bed nucleus of the stria terminalis, medial (BSTM) and LSV; J) the posterior hypothalamic area (PH) and medial supramammillary nucleus (SuMM) and K) periaqueductal gray (PAG). Scale bar  =  100 µm. L. A high magnification view of EGFP-ir cells and fibers inside the suprachiasmatic nucleus (SCN). Arrows indicated EGFP-ir fibers that extended from one nucleus into the contralateral nucleus. Scale bar  =  20 µm. 3V, third ventricle. The animals were sacrificed at ZT12. Cell nuclei were counter-stained in blue in E–L.

Mentions: Extensive EGFP-ir fibers were observed in most known SCN target areas in the septum, preoptic area, hypothalamus, thalamus and midbrain of the adult transgenic mouse brain (Figure 2 and Table 1). Dense EGFP-ir fibers could be seen coursing through the median preoptic area (MnPO), with many of them continued dorsally into the medial bed nucleus of the stria terminalis (BSTM) and the ventral lateral septum (LSV) (Figure 2E and 2I). In the hypothalamus, the densest plexus of EGFP-ir fibers from the SCN began just dorsal and caudal to the nucleus, then vertically projected into the ipsilateral subparaventricular zone (SPa) and continued dorsally to a region ventral to the magnocellular part of the posterior paraventricular hypothalamic nucleus (PVN, Figure 2F). Inside the caudal part of SCN, a handful of EGFP-ir fibers could be seen crossing into the contralateral nucleus (Figure 2L). Posterior to the PVN, the dorsomedial hypothalamic nucleus (DMH) and lateral hypothalamic area (LH) received vast innervations of the EGFP-ir fibers. In contrast, there were few EGFP-ir fibers in the ventromedial hypothalamic nucleus (Figure 2G). A few EGFP-ir fibers were also observed in the Arc, posterior hypothalamic area (PH), lateral and medial supramammillary nucleus (SuMM, Figure 2J). In the thalamus, substantial EGFP-ir fibers could be seen extending dorsally and innervating the paraventricular thalamic nucleus (PVT) (Figure 2H). In the midbrain, intensive EGFP-ir fibers were observed throughout the length of the periaqueductal gray (PAG, Figure 2K), many of which probably extended into the dorsal raphe nucleus (DR, see Figure 3 and below for details).


Efferent projections of prokineticin 2 expressing neurons in the mouse suprachiasmatic nucleus.

Zhang C, Truong KK, Zhou QY - PLoS ONE (2009)

Distribution of EGFP-immunostained fibers in the SCN target areas and complementary expression of PKR2.A–D. Digoxigenin-labeled in situ hybridization showed the expression of PKR2. Arrows indicated PKR2-positive cells. DMH, dorsomedial hypothalamic nucleus; LH, lateral hypothalamic area; LHb, lateral habenular nucleus; LSD, dorsal lateral septum; LSV, ventral lateral septum; MnPO, median optical area; PVN, paraventricular nucleus; PVT, paraventricular thalamic nucleus. Scale bar  =  200 µm. E–K. Immunofluorescence staining showed EGFP-ir fibers in E) the median preoptic area (MnPO) and ventral lateral septum (LSV); F) the subparaventricular zone (SPa) and paraventricular nucleus (PVN); G) the lateral hypothalamic area (LH), dorsomedial hypothalamic nucleus (DMH) and arcuate nucleus (Arc); H) the paraventricular thalamic nucleus (PVT); I) the bed nucleus of the stria terminalis, medial (BSTM) and LSV; J) the posterior hypothalamic area (PH) and medial supramammillary nucleus (SuMM) and K) periaqueductal gray (PAG). Scale bar  =  100 µm. L. A high magnification view of EGFP-ir cells and fibers inside the suprachiasmatic nucleus (SCN). Arrows indicated EGFP-ir fibers that extended from one nucleus into the contralateral nucleus. Scale bar  =  20 µm. 3V, third ventricle. The animals were sacrificed at ZT12. Cell nuclei were counter-stained in blue in E–L.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2747004&req=5

pone-0007151-g002: Distribution of EGFP-immunostained fibers in the SCN target areas and complementary expression of PKR2.A–D. Digoxigenin-labeled in situ hybridization showed the expression of PKR2. Arrows indicated PKR2-positive cells. DMH, dorsomedial hypothalamic nucleus; LH, lateral hypothalamic area; LHb, lateral habenular nucleus; LSD, dorsal lateral septum; LSV, ventral lateral septum; MnPO, median optical area; PVN, paraventricular nucleus; PVT, paraventricular thalamic nucleus. Scale bar  =  200 µm. E–K. Immunofluorescence staining showed EGFP-ir fibers in E) the median preoptic area (MnPO) and ventral lateral septum (LSV); F) the subparaventricular zone (SPa) and paraventricular nucleus (PVN); G) the lateral hypothalamic area (LH), dorsomedial hypothalamic nucleus (DMH) and arcuate nucleus (Arc); H) the paraventricular thalamic nucleus (PVT); I) the bed nucleus of the stria terminalis, medial (BSTM) and LSV; J) the posterior hypothalamic area (PH) and medial supramammillary nucleus (SuMM) and K) periaqueductal gray (PAG). Scale bar  =  100 µm. L. A high magnification view of EGFP-ir cells and fibers inside the suprachiasmatic nucleus (SCN). Arrows indicated EGFP-ir fibers that extended from one nucleus into the contralateral nucleus. Scale bar  =  20 µm. 3V, third ventricle. The animals were sacrificed at ZT12. Cell nuclei were counter-stained in blue in E–L.
Mentions: Extensive EGFP-ir fibers were observed in most known SCN target areas in the septum, preoptic area, hypothalamus, thalamus and midbrain of the adult transgenic mouse brain (Figure 2 and Table 1). Dense EGFP-ir fibers could be seen coursing through the median preoptic area (MnPO), with many of them continued dorsally into the medial bed nucleus of the stria terminalis (BSTM) and the ventral lateral septum (LSV) (Figure 2E and 2I). In the hypothalamus, the densest plexus of EGFP-ir fibers from the SCN began just dorsal and caudal to the nucleus, then vertically projected into the ipsilateral subparaventricular zone (SPa) and continued dorsally to a region ventral to the magnocellular part of the posterior paraventricular hypothalamic nucleus (PVN, Figure 2F). Inside the caudal part of SCN, a handful of EGFP-ir fibers could be seen crossing into the contralateral nucleus (Figure 2L). Posterior to the PVN, the dorsomedial hypothalamic nucleus (DMH) and lateral hypothalamic area (LH) received vast innervations of the EGFP-ir fibers. In contrast, there were few EGFP-ir fibers in the ventromedial hypothalamic nucleus (Figure 2G). A few EGFP-ir fibers were also observed in the Arc, posterior hypothalamic area (PH), lateral and medial supramammillary nucleus (SuMM, Figure 2J). In the thalamus, substantial EGFP-ir fibers could be seen extending dorsally and innervating the paraventricular thalamic nucleus (PVT) (Figure 2H). In the midbrain, intensive EGFP-ir fibers were observed throughout the length of the periaqueductal gray (PAG, Figure 2K), many of which probably extended into the dorsal raphe nucleus (DR, see Figure 3 and below for details).

Bottom Line: Prokineticin 2 (PK2) is one of the candidate output molecules from the SCN.Our data revealed that EGFP-expressing neurons in the SCN, hence representing some of the PK2-expressing neurons, projected to many known SCN target areas, including the ventral lateral septum, medial preoptic area, subparaventricular zone, paraventricular nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamic area and paraventricular thalamic nucleus.The efferent projections of PK2-expressing neurons supported the role of PK2 as an output molecule of the SCN.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California Irvine, Irvine, California, United States of America.

ABSTRACT
The suprachiasmatic nucleus (SCN) in the hypothalamus is the predominant circadian clock in mammals. To function as a pacemaker, the intrinsic timing signal from the SCN must be transmitted to different brain regions. Prokineticin 2 (PK2) is one of the candidate output molecules from the SCN. In this study, we investigated the efferent projections of PK2-expressing neurons in the SCN through a transgenic reporter approach. Using a bacterial artificial chromosome (BAC) transgenic mouse line, in which the enhanced green fluorescence protein (EGFP) reporter gene expression was driven by the PK2 promoter, we were able to obtain an efferent projections map from the EGFP-expressing neurons in the SCN. Our data revealed that EGFP-expressing neurons in the SCN, hence representing some of the PK2-expressing neurons, projected to many known SCN target areas, including the ventral lateral septum, medial preoptic area, subparaventricular zone, paraventricular nucleus, dorsomedial hypothalamic nucleus, lateral hypothalamic area and paraventricular thalamic nucleus. The efferent projections of PK2-expressing neurons supported the role of PK2 as an output molecule of the SCN.

Show MeSH
Related in: MedlinePlus