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Abstract
Purpose
The aim of this study was to assess changes in neuropeptide Y (NPY) immunoreactivity in the hypothalamus and interstitial cells of Cajal (ICC) in the small intestine of rats fed high-fat diets (HFD).
Methods
Male Sprague-Dawley rats (200~250 g body weight) were randomly divided into two groups, which were the control group (normal chow diet for 6 weeks), and the HFD group (rodent diet with 60% kcal fat for 6 weeks). The immunoreactivity of NPY in the hypothalamus and ICC in the small intestine was evaluated after every feed for 6 weeks.
Results
NPY immunoreactivity was observed strongly in the hypothalamic nuclei in the HFD group compared to the control group. The numbers of NPY-immunoreactive (IR) cells were significantly higher in the paraventricular hypothalamic nucleus in the HFD group than in the control group. In the region of Auerbach's plexus (AP) of small intestine, the staining intensity of the ICC-IR cells was reduced in the HFD group compared to the control group. The numbers of ICC in the small intestine with HFD, including ICC in the inner circular and outer longitudinal muscle were significantly lower than in the control group.
Figures and Tables
Fig. 1
NPY immunoreactivity from a control (A, B) and a high-fat diet (HFD; C, D) group in the rat hypothalamus. NPY immunoreactivity was observed in the PVH, VMH and Arc in both groups. NPY immunoreactivity was strongly detected in these hypothalamic nuclei from the HFD compared to the control group. Arc: arcuate nucleus, PVH: paraventricular hypothalamic nucleus, VMH: ventromedial hypothalamic nucleus, HFD: high-fat diet. Scale bars=100µm.
Fig. 2
(A) Representative photomicrographs of the NPY immunoreactivity from a control (a, b) and a HFD (c, d) group in the PVH. The PVH contained large numbers of NPY-IR cell bodies and axon terminals in both groups. The staining intensity of NPY-IR cells was increased in the HFD group compared to the control group. Scale bars=100µm. (B) The numbers of NPY-IR cells in the PVH of the control and the HFD group. PVH: paraventricular hypothalamic nucleus, HFD: high-fat diet. *p<0.05.
Fig. 3
(A) Representative photomicrographs of the NPY immunoreactivity from a control (a, b) and a HFD (c, d) group in the Arc. Strong stained NPY-IR cells were observed in the Arc in both groups. Scale bars= 100µm. (B) The numbers of NPY-IR cells in the Arc of the control and the HFD group. Arc: arcuate nucleus, HFD: high-fat diet.
Fig. 4
(A) Representative photomicrographs of the c-kit immunoreactivity from the control and the HFD group in the small intestine. In the region of Auerbach's plexus (AP), the staining intensity of the c-kit IR cells was reduced in the HFD group compared to the control group. (B) Small arrows indicate c-kit IR cells within the AP in the control group. AP: Auerbach's (myenteric) plexus, CM: circular muscle layer, LM: longitudinal muscle layer, SM: submucosa, HFD: high-fat diet. Scale bars=100µm.
Fig. 5
(A) Representative photomicrographs of the c-kit immunoreactivity from the control and the HFD group in the whole musculature of small intestine. In the inner CM and outer LM, the staining intensity of the c-kit IR cells was reduced in the HFD group compared to the control group. Scale bars=100µm. (B) Quantification of the c-kit-IR cell proportions in the small intestine from the controls and the HFD groups. *p<0.05. AP: Auerbach's (myenteric) plexus, CM: circular muscle layer, LM: longitudinal muscle layer, SM: submucosa, HFD: high-fat diet.
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