Abstract
The phases of many circadian rhythms differ between diurnal and nocturnal species. However, rhythms within the hypothalamic suprachiasmatic nucleus (SCN), which contains the central circadian pacemaker, are very similar, suggesting that the mechanisms underlying phase preference lie downstream of the SCN. Rhythms in Fos expression in the ventral subparaventricular zone (vSPVZ), a major target of the SCN, differ substantially between diurnal Nile grass rats and nocturnal lab rats, raising the possibility that the vSPVZ modulates the effects of SCN signals at its targets. To understand better how and where the SCN and vSPVZ communicate circadian signals within the grass rat brain, we mapped their projections using the anterograde tracer biotinylated dextran amine (BDA). Adult female grass rats received unilateral BDA injections directed at the SCN or vSPVZ and their brains were perfusion-fixed several days later. Immunohistochemistry revealed that the distribution patterns of SCN and vSPVZ efferents were very similar. Labeled fibers originating in each region were heavily concentrated in the medial preoptic area, paraventricular thalamic nucleus, the subparaventricular zone, and the hypothalamic paraventricular and dorsomedial nuclei. BDA-labeled fibers from the SCN and vSPVZ formed appositions with orexin neurons and gonadotropin-releasing hormone neurons, two cell populations whose rhythms in Fos expression track temporally reversed patterns of locomotor and reproductive behavior, respectively, in diurnal and nocturnal rodents. These data demonstrate that projections of the SCN and vSPVZ are highly conserved in diurnal and nocturnal rodents, and the vSPVZ projections may enable it to modulate the responsiveness of target cells to signals from the SCN.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 146-161 |
| Number of pages | 16 |
| Journal | Brain Research |
| Volume | 1367 |
| DOIs | |
| State | Published - Jan 7 2011 |
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Keywords
- Circadian rhythm
- Diurnality
- Gonadotropin-releasing hormone
- Orexin
- Suprachiasmatic nucleus
- Ventral subparaventricular zone
ASJC Scopus subject areas
- Neuroscience(all)
- Clinical Neurology
- Developmental Biology
- Molecular Biology
Cite this
Projections of the suprachiasmatic nucleus and ventral subparaventricular zone in the Nile grass rat (Arvicanthis niloticus). / Schwartz, Michael D.; Urbanski, Henryk; Nunez, Antonio A.; Smale, Laura.
In: Brain Research, Vol. 1367, 07.01.2011, p. 146-161.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Projections of the suprachiasmatic nucleus and ventral subparaventricular zone in the Nile grass rat (Arvicanthis niloticus)
AU - Schwartz, Michael D.
AU - Urbanski, Henryk
AU - Nunez, Antonio A.
AU - Smale, Laura
PY - 2011/1/7
Y1 - 2011/1/7
N2 - The phases of many circadian rhythms differ between diurnal and nocturnal species. However, rhythms within the hypothalamic suprachiasmatic nucleus (SCN), which contains the central circadian pacemaker, are very similar, suggesting that the mechanisms underlying phase preference lie downstream of the SCN. Rhythms in Fos expression in the ventral subparaventricular zone (vSPVZ), a major target of the SCN, differ substantially between diurnal Nile grass rats and nocturnal lab rats, raising the possibility that the vSPVZ modulates the effects of SCN signals at its targets. To understand better how and where the SCN and vSPVZ communicate circadian signals within the grass rat brain, we mapped their projections using the anterograde tracer biotinylated dextran amine (BDA). Adult female grass rats received unilateral BDA injections directed at the SCN or vSPVZ and their brains were perfusion-fixed several days later. Immunohistochemistry revealed that the distribution patterns of SCN and vSPVZ efferents were very similar. Labeled fibers originating in each region were heavily concentrated in the medial preoptic area, paraventricular thalamic nucleus, the subparaventricular zone, and the hypothalamic paraventricular and dorsomedial nuclei. BDA-labeled fibers from the SCN and vSPVZ formed appositions with orexin neurons and gonadotropin-releasing hormone neurons, two cell populations whose rhythms in Fos expression track temporally reversed patterns of locomotor and reproductive behavior, respectively, in diurnal and nocturnal rodents. These data demonstrate that projections of the SCN and vSPVZ are highly conserved in diurnal and nocturnal rodents, and the vSPVZ projections may enable it to modulate the responsiveness of target cells to signals from the SCN.
AB - The phases of many circadian rhythms differ between diurnal and nocturnal species. However, rhythms within the hypothalamic suprachiasmatic nucleus (SCN), which contains the central circadian pacemaker, are very similar, suggesting that the mechanisms underlying phase preference lie downstream of the SCN. Rhythms in Fos expression in the ventral subparaventricular zone (vSPVZ), a major target of the SCN, differ substantially between diurnal Nile grass rats and nocturnal lab rats, raising the possibility that the vSPVZ modulates the effects of SCN signals at its targets. To understand better how and where the SCN and vSPVZ communicate circadian signals within the grass rat brain, we mapped their projections using the anterograde tracer biotinylated dextran amine (BDA). Adult female grass rats received unilateral BDA injections directed at the SCN or vSPVZ and their brains were perfusion-fixed several days later. Immunohistochemistry revealed that the distribution patterns of SCN and vSPVZ efferents were very similar. Labeled fibers originating in each region were heavily concentrated in the medial preoptic area, paraventricular thalamic nucleus, the subparaventricular zone, and the hypothalamic paraventricular and dorsomedial nuclei. BDA-labeled fibers from the SCN and vSPVZ formed appositions with orexin neurons and gonadotropin-releasing hormone neurons, two cell populations whose rhythms in Fos expression track temporally reversed patterns of locomotor and reproductive behavior, respectively, in diurnal and nocturnal rodents. These data demonstrate that projections of the SCN and vSPVZ are highly conserved in diurnal and nocturnal rodents, and the vSPVZ projections may enable it to modulate the responsiveness of target cells to signals from the SCN.
KW - Circadian rhythm
KW - Diurnality
KW - Gonadotropin-releasing hormone
KW - Orexin
KW - Suprachiasmatic nucleus
KW - Ventral subparaventricular zone
UR - http://www.scopus.com/inward/record.url?scp=78650512911&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78650512911&partnerID=8YFLogxK
U2 - 10.1016/j.brainres.2010.10.058
DO - 10.1016/j.brainres.2010.10.058
M3 - Article
C2 - 20971082
AN - SCOPUS:78650512911
VL - 1367
SP - 146
EP - 161
JO - Brain Research
JF - Brain Research
SN - 0006-8993
ER -