Canna~Fangled Abstracts

2-AG into the lateral hypothalamus increases REM sleep and cFos expression in melanin concentrating hormone neurons in rats.

By May 30, 2013No Comments

Pub Med2-AG into the lateral hypothalamus increases REM sleep and cFos expression in melanin concentrating hormone neurons in rats.

Source

Grupo de Neurociencias, Laboratorio de Canabinoides, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, D.F., Mexico.

Abstract

Orexins/hypocretins (OX) and melanin-concentrating hormone (MCH) neurons located in the lateral hypothalamus seem to modulate different stages of the sleep-wake cycle. OX are necessary for wakefulness and MCH appears to regulate rapid eye movement sleep (REMS). Likewise, endocannabinoids, the endogenous ligands for cannabinoid receptors 1 and 2 (CB1R, CB2R), also modulate REMS in rats. Moreover, it has been shown that the activation of the CB1R in the lateral hypothalamus of rats excites MCH neurons while inhibiting OX neurons in in vitro preparations. Hence, we assessed the effects of 2-arachidonoylglicerol (2-AG, an endocannabinoid) in the lateral hypothalamus on the sleep-wake cycle of rats. We also utilized the CB1R inverse agonist AM251 to further support the involvement of this receptor, and we performed double immunofluorescence experiments to detect c-Fos, as a marker of neural activation, in OX and in MCH neurons to determine which neurons were activated. Our results indicate that 2-AG increases REMS through CB1R activation, and increases c-Fos expression in MCH neurons. These results suggest that endocannabinoid activation of the CB1R in the lateral hypothalamus, which activates MCH neurons, is one mechanism by which REMS is triggered.
Copyright © 2013 Elsevier Inc. All rights reserved.
PMID:

 23603032
[PubMed – as supplied by publisher]

LinkOut – more resources

Full Text Sources

elsevierHighlights

•

Bilateral intralateral hypothalamic administration of 2-AG increases REMS in rats.

•

2-AG increases REMS, through a CB1R activation.

•

CB1R activation by 2-AG increases c-Fos expression in MCH neurons.

Graphical abstract

 

Abbreviations

  • OX, Orexins/hypocretins;
  • MCH, melanin-concentrating hormone;
  • CB1R, cannabinoid receptor 1;
  • CB2R,cannabinoid receptor 2;
  • SWC, sleep-wake cycle;
  • W, wakefulness;
  • SWS, slow wave sleep;
  • REMS, rapid eye movement sleep;
  • eCBs, endocannabinoids;
  • 2-AG, 2-araquidonoylglicerol;
  • AEA, anandamide;
  • OLE,oleamide;
  • PAR1, protease-activated receptor 1;
  • FAAH, fatty acid amide hydrolase;
  • PBS, phosphate-buffer-saline;
  • PFH, paraformaldehyde;
  • LDT, laterodorsal tegmental nuclei;
  • PPT, pedunculopontine tegmental nuclei;
  • PACAP, pituitary adenylyl cyclase-activating polypeptide;
  • FTG, gigantocellular tegmental field;
  • PnO, pontine reticular nucleus;
  • ACEA, arachidonyl-2′-chloroethylamide;
  • IL-1, interleukin-1

Keywords

  • Rapid eye movement sleep;
  • 2-arachidonoylglicerol;
  • Cannabinoid receptor 1;
  • Lateral hypothalamus;
  • Orexins/hypocretins;
  • Melanin-concentrating hormone

Figures and tables from this article:

Full-size image (54 K)
Fig. 1.

Effects of bilateral intralateral hypothalamic administration of 2-AG (0.01 μg or 0.1 μg or 1 μg), AM251 (1.4 μg), or 2-AG (0.01 μg) in combination with AM251, on the sleep–wake cycle of rats, for the first 12 h and for the last 12 h of recording (min), corresponding to both the dark phase (left panel) and to the light phase (right panel) of the cycle (n = 10, per group); *p < 0.05, **p < 0.001 vs. Vehicle; §p < 0.05, §§p < 0.001 vs. 2-AG (0.01 μg).

Full-size image (92 K)
Fig. 2.

Representative photomicrographs of brain coronal sections corresponding to double immunofluorescence against orexin/hypocretin-A (A; top; left panel) or MCH (B; top; right panel) and c-Fos, for both cases (C, D; bottom). Amplifications are shown for orexin/hypocretin A (left panel), c-Fos (middle panel) and merged for orexin/hypocretin A and c-Fos (right panel), corresponding to vehicle (E) or 0.01 μg of 2-AG (G); and for MCH (left panel), c-Fos (middle panel) and merged for MCH and c-Fos, corresponding to vehicle (F) or 0.01 μg of 2-AG (H). 3V: third ventricle. Single arrowheads denote an example of cells positive for both peptide (OX + or MCH +) and c-Fos.

Table 1.Time spent (min) in W, SWS and REMS depicted in 4 h blocks (1–4, 5–8, 9–12, 13–16, 17–20 and 21–24), following the bilateral intralateral hypothalamic administration of 2-AG (0.01 μg or 0.1 μg or 1 μg), AM251 (1.4 μg), or 2-AG (0.01 μg) in combination with AM251, for both the first (Dark) and last (Light) 12 h of recording (n = 10, per group); *p < 0.05, **p < 0.001 vs. Vehicle; §p < 0.05, §§p < 0.001 vs. 2-AG (0.01 μg).
View Within Article
Table 2.Latencies to SWS and REMS, bout frequency (number) and bout duration (min), corresponding to the dark phase of the cycle, for W, SWS and REMS among treatments; **p < 0.001 vs. Vehicle; *p < 0.05 vs. Vehicle; §p < 0.05 vs. 2-AG (0.01 μg).
View Within Article
Table 3.Cell count for c-Fos positive (+), OX +, MCH + and double + cells for c-Fos/OX and c-Fos/MCH, following the bilateral administration of 0.01 μg of 2-AG or its vehicle into the lateral hypothalamus of freely behaving rats (n = 6, per group). 2-AG significantly increased c-Fos expression in MCH cells. 88.8% of total MCH + cells and 43.7% of total OX + cells were also c-Fos +, following 2-AG administration, while 17.4% of total MCH + cells and 51.9% of total OX + cells were also c-Fos + in the control group; ** p < .001 vs. Vehicle.
View Within Article
Corresponding author contact information
Corresponding author at: Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Apdo. Postal 70-250, México, D. F. 04510, Mexico. Tel.: + 52 55 623 2509; fax: + 52 55 623 2241.

Copyright © 2013 Elsevier Inc. All rights reserved.

prisoner of the system2
http://www.ncbi.nlm.nih.gov/pubmed/23603032