Oleoylethanolamide affects food intake and sleep-waking cycle through a hypothalamic modulation

Oleoylethanolamide (OEA) is an endogenous molecule related to endocannabinoids (eCBs) that induces satiety. It binds to the peroxisome-proliferator-activated receptor alpha (PPAR alpha). PPAR alpha is involved in feeding regulation and it has been proposed to play a role in sleep modulation. The objective of the present work is to show if this molecule modifies the sleep-waking cycle through central mechanisms. We have found that the peripheral administration of OEA reduces food intake and increases waking with a concomitant reduction of rapid eye movement sleep. Additionally, this treatment produces deactivation of the lateral hypothalamus, as inferred from the c-Fos expression evaluation. Finally, intra-lateral hypothalamus injection of OEA has mirrored the effects induced by this molecule when it is peripherally administered. In conclusion, we show for the very first time that OEA can modify the sleep-waking cycle and food intake, apparently mediated by the lateral hypothalamus.

[Sleep genes]

INTRODUCTION

Sleep is a non-learned adaptive strategy that depends on the expression of several neurotransmitters and other molecules. The expression of some of these molecules depends on a number of different genes. Sleep disorders are associated with an inadequate expression of some molecules, which therefore indicates that these genes that code for these molecules participate in the regulation of normal sleep.

AIM

To discuss the evidence on gene regulation over the occurrence of sleep and its architecture, as well as of sleep disorders, which supports the participation of specific genes.

DEVELOPMENT

We describe the evidence on sleep in mammals, particularly in humans, in addition to studies with twins that demonstrate the influence of genes on sleep regulation. We also discuss several sleep disorders, which in this study only serves to emphasise how certain specific genes, under normal conditions, participate in the expression of sleep. Furthermore, evidence is also provided for other molecules, such as endocannibinoids, involved in sleep regulation. Lastly, we report on studies conducted with different strains of mice that show differences in the amount of sleep they express, possibly as an epiphenomenon of their different genetic loads.

CONCLUSIONS

A number of different genes have been described as those responsible for making us sleep, although sleeping also depends on our interaction with the environment. This interaction is what makes us express sleep at times that are best suited to favouring our survival.

[Effect of mitomycin C on corneal endothelium cells. In vitro study]

PURPOSE

Mitomycin C is an antibiotic with a demonstrated antiproliferative capacity as an inhibitor of fibroblastic cells proliferation. Its use has been extended in glaucoma surgery. In the present study, we evaluated mitomycin C effect on cell culture monolayer of rabbit corneal endothelium.

METHODS

The source of corneal endothelium for cell culture was New Zealand albino rabbit eyes. Desegregation of cells was carried out with mechanic and enzymatic dissociation from corneal endothelium and Descemet membrane. Culture medium was EMEM. Three treatment groups of plates were exposed to three different concentrations of mitomycin C 2x10(-3) mg/ml, 2x10(-2) mg/ml and 2x10(-1) mg/ml. Control and witness plate groups were also established. The morphometric study was performed through quantitative analysis with a video system connected to the light microscope.

RESULTS

Different morphological changes related with cell size, cytoplasm and dyeing were seen at the morphological study and several degenerative signs were established indicating cellular death and a very decrease of the cellular population. In the groups treated with minimal dose (2x10(-3) mg/ml) and 3 days evolution time, cellular population was 434 cels/mm(2), 7 evolution days group cell density was 300.97cels/mm(2), and at 14 days it was 201.88 cels/mm(2). The percentage of survival in all the groups of treated cells was under 50%.

CONCLUSIONS

Mitomycin C in concentrations and exposure time as used in this study has a potent lethal effect on this cellular type that compromises to a greater or smaller extent their function and integrity.