Dataset Information

High-fat diet increases pain behaviors in rats with or without obesity.

ABSTRACT: Obesity is associated with increased risk for chronic pain. Basic mechanisms for this association are poorly understood. Using a milder version of a radicular pain model, local inflammation of the dorsal root ganglion (DRG), we observed marked increases in mechanical and cold allodynia in rats of both sexes that were maintained on a high-fat diet (HFD) for 6 weeks prior to DRG inflammation. Notably, this increase in pain-related behaviors occurred in both Long-Evans and Sprague-Dawley rats despite the fact that the 6-week HFD exposure induced obesity (e.g., increased insulin, leptin, weight, and percent body fat) in the Long-Evans, but not Sprague-Dawley, strains. This suggested that HFD, rather than obesity per se, increased pain behaviors. Increased pain behaviors were observed even after a much shorter (1 week) exposure to the HFD but the effect was smaller. HFD also increased behavioral responses and paw swelling to paw injection of complete Freund's adjuvant, a model of peripheral inflammatory pain. No change was detected in plasma cytokine levels in HFD rats. However, increased macrophage infiltration of the DRG was observed in response to the HFD, absent any pain model. The results suggest that HFD can increase pain even when it does not cause obesity.

SUBMITTER: Song Z

PROVIDER: S-EPMC5583349 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

High-fat diet increases pain behaviors in rats with or without obesity.

Song Zongbin Z Xie Wenrui W Chen Sisi S Strong Judith A JA Print Mason S MS Wang Joy I JI Shareef Aleeya F AF Ulrich-Lai Yvonne M YM Zhang Jun-Ming JM

Scientific reports 20170904 1

Obesity is associated with increased risk for chronic pain. Basic mechanisms for this association are poorly understood. Using a milder version of a radicular pain model, local inflammation of the dorsal root ganglion (DRG), we observed marked increases in mechanical and cold allodynia in rats of both sexes that were maintained on a high-fat diet (HFD) for 6 weeks prior to DRG inflammation. Notably, this increase in pain-related behaviors occurred in both Long-Evans and Sprague-Dawley rats despi ...[more]

PMID: 28871134

Similar Datasets

Project description:Reduced hepatic glycogenesis is one of the most important causes of metabolic abnormalities in non‑alcoholic fatty liver disease. Octreotide, a somatostatin analogue, has been demonstrated to promote weight loss and improve metabolic disorders in mice with high fat diet (HFD)‑induced obesity. However, whether octreotide affects hepatic glycogenesis is unknown. The aim of the present study was to verify the effects of octreotide on hepatic glycogenesis in rats with HFD‑induced obesity. Male Sprague‑Dawley rats were fed a standard diet or a HFD for 24 weeks. Obese rats from the HFD group were further divided into a HFD‑control group and an octreotide‑administered group. Rats in the latter group were injected with octreotide for 8 days. Glucose and insulin tolerance tests were performed, and the area under the curve (AUC) was calculated. Following sacrifice, their body weights and lengths, fasting plasma glucose (FPG), fasting insulin (FINS), serum triglyceride (TG), total cholesterol (TC), free fatty acid (FFA), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. In addition, Lee's index and the homeostatic model assessment index were calculated. Hepatic TG, FFA levels and glycogen content were first determined. Hepatic steatosis in the obese rats was assessed based on hematoxylin and eosin and Oil Red O staining. Human hepatoblastoma HepG2 cells were divided into a control group, a palmitate (PA)‑treated group and a PA + octreotide‑treated group. Establishment of the in vitro fatty liver model using HepG2 cells was confirmed by Oil Red O staining. The expression of phosphorylated Akt and glycogen synthase kinase 3β (GSK3β) was detected by western blotting, and glycogen synthase (GS) mRNA levels were detected by reverse transcription‑quantitative polymerase chain reaction. Compared with the control group, the body weight, Lee's index, AUC of the intraperitoneal glucose tolerance test and intraperitoneal insulin tolerance test, levels of FPG, FINS, TG, TC, FFA, ALT and AST, and HOMA index values were significantly increased in the obese rats. The body weight, levels of FPG and FINS, and the HOMA index were significantly reduced following octreotide treatment, whereas the decrease in Lee's index, the blood levels of ALT, AST, TC, TG and FFA, and the AUC did not reach statistical significance. Hepatic TG and FFA levels were significantly increased and hepatic glycogen content was significantly decreased in rats with HFD‑induced obesity when compared with those in the control group. Octreotide intervention restored these alterations. The expression levels of phosphorylated Akt and GSK3β protein expression, as well as GS mRNA levels in the HFD group were lower when compared with those in the control group, whereas octreotide treatment reversed these reductions. The in vitro experiments demonstrated that the reduced levels of phosphorylated Akt and GSK3β protein, and GS mRNA in the PA‑treated group were significantly reversed by octreotide treatment. In conclusion, the results indicate that octreotide improved hepatic glycogenesis and decreased FPG concentration in rats with HFD‑induced obesity. These mechanisms may be associated with increased GS activity via the promotion of GSK3β phosphorylation. Therefore, octreotide may be regarded as a novel therapeutic strategy for HFD‑induced obesity and obesity‑associated metabolic disorders.

Dataset Information

High-fat diet increases pain behaviors in rats with or without obesity.

Publications

High-fat diet increases pain behaviors in rats with or without obesity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets