Ghrelin acts on rat dorsal vagal complex to stimulate feeding via arcuate neuropeptide Y/agouti-related peptide neurons activation.

Aug 19, 2010Sheng li xue bao : [Acta physiologica Sinica]

Ghrelin stimulates eating by activating appetite neurons through the brainstem and hypothalamus in rats

AI simplified

GLP-1 Therapies on OpenScience ↗PubMed ↗

Abstract

Ghrelin administration in the brain increased cumulative food intake significantly at 1, 2, and 3 hours after injection, with the peak response observed at 2 hours.

Ghrelin was delivered at a concentration of 20 pmol in 0.5 μL to the dorsal vagal complex of rat brains.
The cumulative food intake increased significantly after ghrelin injection, reaching the highest levels at 2 hours.
NPY and AgRP mRNA levels in the hypothalamic arcuate nucleus increased significantly compared to the control group injected with saline.
The total number and mean optical density of NPY-positive neurons in the arcuate nucleus also increased following ghrelin treatment.
These findings suggest that activation of NPY/AgRP neurons in the arcuate nucleus plays a role in the feeding response to ghrelin applied in the brainstem.

AI simplified

Ghrelin, an endogenous ligand for the growth hormone secretagogue (GHS) receptor, stimulates feeding and increases body weight. The primary action site of ghrelin has been reported to be the neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons in the hypothalamic arcuate nucleus (ARC). In addition to the hypothalamus, the caudal brainstem also appears to be an important mediator for the orexigenic activity of ghrelin. However, it is not clear whether ghrelin applied directly to the caudal brainstem activates forebrain structures. The aim of this study was to determine whether recruitment of forebrain structures was required for hyperphagic responses stimulated by ghrelin delivery within the caudal brainstem. In our experiment, all rats were surgically implanted with indwelling cannulas in the dorsal vagal complex (DVC), and ghrelin (20 pmol in 0.5 μL) was delivered to the DVC. After the injection, the orexigenic response to ghrelin was recorded by Feeding and Activity Analyser, and NPY/AgRP mRNA expressions in rat hypothalamus were detected by real-time PCR. In addition, the NPY immunoreactive neurons in the ARC were assayed by immunohistochemistry. The results showed that ghrelin significantly increased cumulative food intake at 1, 2 and 3 h after ghrelin injection, maximal response occurring at 2 h after injection. NPY/AgRP mRNA levels in ARC treated with ghrelin increased significantly compared with those in control group (injected with saline). The highest levels of NPY and AgRP mRNA were detected at 2 h after injection. The total number and mean optical density of NPY-positive neurons increased in ghrelin treated rats compared with those in control group. Consistently, ghrelin's effect was most pronounced at 2 h after injection. Taken together, we conclude that the activation of NPY/AgRP neurons in the ARC is involved in the mediation of the hyperphagic response to brainstem ghrelin administration in neurologically intact rats.

Ghrelin acts on rat dorsal vagal complex to stimulate feeding via arcuate neuropeptide Y/agouti-related peptide neurons activation.

Abstract

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the glp-1 therapies brief

Abstract

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the glp-1 therapies brief