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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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A subset of EGFP-ir cells in the SCN co-expressed vasopressin (AVP).A–C. Double immunostaining against EGFP and AVP in the SCN. Cells that were positive for both EGFP and AVP signals were marked by arrows. D. The localizations of EGFP- and AVP-positive neurons in the SCN were shown schematically. E–G. Double immunostaining of EGFP and vasoactive intestinal peptide (VIP) in the SCN. No neuron was positive for both EGFP and VIP signals. H. The localizations of EGFP- and VIP-positive neurons in the SCN were shown schematically. In all images, the boundary of SCN was indicated by the dotted line. The third ventricle was to the right in all images. The animals were sacrificed at ZT9. Scale bar  =  20 µm.
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pone-0007151-g006: A subset of EGFP-ir cells in the SCN co-expressed vasopressin (AVP).A–C. Double immunostaining against EGFP and AVP in the SCN. Cells that were positive for both EGFP and AVP signals were marked by arrows. D. The localizations of EGFP- and AVP-positive neurons in the SCN were shown schematically. E–G. Double immunostaining of EGFP and vasoactive intestinal peptide (VIP) in the SCN. No neuron was positive for both EGFP and VIP signals. H. The localizations of EGFP- and VIP-positive neurons in the SCN were shown schematically. In all images, the boundary of SCN was indicated by the dotted line. The third ventricle was to the right in all images. The animals were sacrificed at ZT9. Scale bar  =  20 µm.

Mentions: A closer look at the regional distribution of EGFP-ir neurons inside the SCN showed that the EGFP-ir neurons and processes were limited to the dorsomedial and lateral edges of the nucleus in the rostral and anterior-central compartments, creating the appearance of a shell. In the posterior central portion of the SCN, majority of the EGFP-ir cells were found in the medial and dorsomedial areas. While in the caudal quadrant, EGFP-ir cells dispersed throughout the SCN (Figure 5). As for the phenotype of the EGFP-ir neurons, about 60% of the EGFP-ir neurons in the SCN were also positive for vasopressin (AVP) at ZT12, as shown by double immunostaining with antibodies against AVP and EGFP (Figure 6A–D, EGFP+ cells: 606±74; AVP+ cells: 2574±198; EGFP+/AVP+ cells: 357±32, three animals). On the contrary, no EGFP-ir cell was positive for vasoactive intestinal peptide (VIP) at the same condition (Figure 6E–H).


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

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

A subset of EGFP-ir cells in the SCN co-expressed vasopressin (AVP).A–C. Double immunostaining against EGFP and AVP in the SCN. Cells that were positive for both EGFP and AVP signals were marked by arrows. D. The localizations of EGFP- and AVP-positive neurons in the SCN were shown schematically. E–G. Double immunostaining of EGFP and vasoactive intestinal peptide (VIP) in the SCN. No neuron was positive for both EGFP and VIP signals. H. The localizations of EGFP- and VIP-positive neurons in the SCN were shown schematically. In all images, the boundary of SCN was indicated by the dotted line. The third ventricle was to the right in all images. The animals were sacrificed at ZT9. Scale bar  =  20 µm.
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Related In: Results  -  Collection

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

pone-0007151-g006: A subset of EGFP-ir cells in the SCN co-expressed vasopressin (AVP).A–C. Double immunostaining against EGFP and AVP in the SCN. Cells that were positive for both EGFP and AVP signals were marked by arrows. D. The localizations of EGFP- and AVP-positive neurons in the SCN were shown schematically. E–G. Double immunostaining of EGFP and vasoactive intestinal peptide (VIP) in the SCN. No neuron was positive for both EGFP and VIP signals. H. The localizations of EGFP- and VIP-positive neurons in the SCN were shown schematically. In all images, the boundary of SCN was indicated by the dotted line. The third ventricle was to the right in all images. The animals were sacrificed at ZT9. Scale bar  =  20 µm.
Mentions: A closer look at the regional distribution of EGFP-ir neurons inside the SCN showed that the EGFP-ir neurons and processes were limited to the dorsomedial and lateral edges of the nucleus in the rostral and anterior-central compartments, creating the appearance of a shell. In the posterior central portion of the SCN, majority of the EGFP-ir cells were found in the medial and dorsomedial areas. While in the caudal quadrant, EGFP-ir cells dispersed throughout the SCN (Figure 5). As for the phenotype of the EGFP-ir neurons, about 60% of the EGFP-ir neurons in the SCN were also positive for vasopressin (AVP) at ZT12, as shown by double immunostaining with antibodies against AVP and EGFP (Figure 6A–D, EGFP+ cells: 606±74; AVP+ cells: 2574±198; EGFP+/AVP+ cells: 357±32, three animals). On the contrary, no EGFP-ir cell was positive for vasoactive intestinal peptide (VIP) at the same condition (Figure 6E–H).

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