Abstract
The orexins are neuropeptides originally reported to be involved in the stimulation of food intake. However, analysis of orexin immunoreactive fibres have revealed the densest innervation in brain sites involved in arousal and sleep-wake control, notably the noradrenergic locus coeruleus, an area that also expresses orexin receptor 1 (OX1R) messenger RNA (mRNA). We report here that, in the rat, a single intracerebroventricular injection of orexin A (1 and 3 nmol) or orexin B (3 nmol), during the early light phase, did not increase food intake over the first 4 h postinjection. However, the frequency of active behaviors such as grooming, rearing, burrowing and locomotion increased. Feeding behavior and food intake subsequently decreased over the following 20 h (4-24 h postinjection period) in the orexin A 3 nmol injected group whilst the frequency of inactive behavior (still or asleep) in this group increased. Using riboprobes, we performed in situ hybridization histochemistry to map the distribution of orexin receptor 2 (OX2R) mRNA within the rat brainstem. We report here, for the first time, the presence of OX2R mRNA in the nucleus of the solitary tract and the lateral reticular field (LRt). The LRt is a brainstem site that, amongst other functions, is implicated in attention and wakefulness. This distribution of OX2R and the effects on behavior support recent reports that the orexins might modulate central nervous system arousal and sleep-wake mechanisms rather than exclusively being involved in the control of food intake.
| Original language | English |
|---|---|
| Pages (from-to) | 27-34 |
| Number of pages | 8 |
| Journal | Brain Research |
| Volume | 907 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - 13 Jul 2001 |
| Externally published | Yes |
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Keywords
- Behavior
- Brainstem
- In situ hybridization
- Orexin
- Receptor
- Sleep-wake
ASJC Scopus subject areas
- Neuroscience(all)
- Molecular Biology
- Developmental Biology
- Clinical Neurology
Cite this
Orexins : Effects on behavior and localisation of orexin receptor 2 messenger ribonucleic acid in the rat brainstem. / Sunter, David; Morgan, Irene; Edwards, C. Mark B.; Dakin, Catherine L.; Murphy, Kevin G.; Gardiner, James; Taheri, Shahrad; Rayes, Esraa; Bloom, Stephen R.
In: Brain Research, Vol. 907, No. 1-2, 13.07.2001, p. 27-34.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Orexins
T2 - Effects on behavior and localisation of orexin receptor 2 messenger ribonucleic acid in the rat brainstem
AU - Sunter, David
AU - Morgan, Irene
AU - Edwards, C. Mark B.
AU - Dakin, Catherine L.
AU - Murphy, Kevin G.
AU - Gardiner, James
AU - Taheri, Shahrad
AU - Rayes, Esraa
AU - Bloom, Stephen R.
PY - 2001/7/13
Y1 - 2001/7/13
N2 - The orexins are neuropeptides originally reported to be involved in the stimulation of food intake. However, analysis of orexin immunoreactive fibres have revealed the densest innervation in brain sites involved in arousal and sleep-wake control, notably the noradrenergic locus coeruleus, an area that also expresses orexin receptor 1 (OX1R) messenger RNA (mRNA). We report here that, in the rat, a single intracerebroventricular injection of orexin A (1 and 3 nmol) or orexin B (3 nmol), during the early light phase, did not increase food intake over the first 4 h postinjection. However, the frequency of active behaviors such as grooming, rearing, burrowing and locomotion increased. Feeding behavior and food intake subsequently decreased over the following 20 h (4-24 h postinjection period) in the orexin A 3 nmol injected group whilst the frequency of inactive behavior (still or asleep) in this group increased. Using riboprobes, we performed in situ hybridization histochemistry to map the distribution of orexin receptor 2 (OX2R) mRNA within the rat brainstem. We report here, for the first time, the presence of OX2R mRNA in the nucleus of the solitary tract and the lateral reticular field (LRt). The LRt is a brainstem site that, amongst other functions, is implicated in attention and wakefulness. This distribution of OX2R and the effects on behavior support recent reports that the orexins might modulate central nervous system arousal and sleep-wake mechanisms rather than exclusively being involved in the control of food intake.
AB - The orexins are neuropeptides originally reported to be involved in the stimulation of food intake. However, analysis of orexin immunoreactive fibres have revealed the densest innervation in brain sites involved in arousal and sleep-wake control, notably the noradrenergic locus coeruleus, an area that also expresses orexin receptor 1 (OX1R) messenger RNA (mRNA). We report here that, in the rat, a single intracerebroventricular injection of orexin A (1 and 3 nmol) or orexin B (3 nmol), during the early light phase, did not increase food intake over the first 4 h postinjection. However, the frequency of active behaviors such as grooming, rearing, burrowing and locomotion increased. Feeding behavior and food intake subsequently decreased over the following 20 h (4-24 h postinjection period) in the orexin A 3 nmol injected group whilst the frequency of inactive behavior (still or asleep) in this group increased. Using riboprobes, we performed in situ hybridization histochemistry to map the distribution of orexin receptor 2 (OX2R) mRNA within the rat brainstem. We report here, for the first time, the presence of OX2R mRNA in the nucleus of the solitary tract and the lateral reticular field (LRt). The LRt is a brainstem site that, amongst other functions, is implicated in attention and wakefulness. This distribution of OX2R and the effects on behavior support recent reports that the orexins might modulate central nervous system arousal and sleep-wake mechanisms rather than exclusively being involved in the control of food intake.
KW - Behavior
KW - Brainstem
KW - In situ hybridization
KW - Orexin
KW - Receptor
KW - Sleep-wake
UR - http://www.scopus.com/inward/record.url?scp=0035854570&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035854570&partnerID=8YFLogxK
U2 - 10.1016/S0006-8993(01)02344-7
DO - 10.1016/S0006-8993(01)02344-7
M3 - Article
VL - 907
SP - 27
EP - 34
JO - Brain Research
JF - Brain Research
SN - 0006-8993
IS - 1-2
ER -