Influence of macronutrient composition of commercial diets on circulating leptin and adiponectin concentrations in overweight dogs

Leptin and adiponectin play important roles in obesity-related inflammation and comorbidities. Previous research suggests that alterations in dietary macronutrient composition can modify circulating leptin and adiponectin concentrations in people, but limited research on this subject has been performed in dogs. This study investigated the effects of commercial high protein (HP), high fat (HF) and high carbohydrate medium protein (HCMP) diets on baseline (T-1 ) concentrations, post-prandial peak concentrations and total release in a ten-hour time span of leptin and adiponectin in dogs, when compared to a maintenance high carbohydrate low protein (HCLP) diet. Thirty-six overweight dogs were fed the HCLP diet in a one-week control period, after which the animals were assigned to one of three groups. In three four-week periods, each group was fed all test diets in a different sequence. At the last day of each period, blood was sampled at one hour before feeding (T-1 ) and at three (T3 ), six (T6 ) and nine (T9 ) hours after feeding. Feeding caused peak leptin concentrations at T6 and T9 (p < .001). No significant post-prandial change in adiponectin concentrations was found (p = .056). The HP diet resulted in lower leptin peak concentrations (p = .004) and AUCT-1-T9 (p = .01), but none of the diets influenced baseline leptin concentrations (p = .273). Baseline adiponectin concentrations were lower for the HF diet (p = .018) and HCMP (p < .001), and the HP, HF and HCMP AUCT-1-T9 (p < .001) were lower compared with the HCLP diet. Female dogs had lower adiponectin baseline concentrations (p = .041) and AUCT-1-T9 (p = .023) than male dogs. In conclusion, the HP diet was associated with the lowest post-prandial peak leptin concentration and the least decrease in adiponectin release, suggesting that a HP diet may improve immune-metabolic health and post-prandial satiety in overweight dogs

Expression stability of reference genes for quantitative RT-PCR of healthy and diseased pituitary tissue samples varies between humans, mice, and dogs

Pituitary surgery generates pituitary tissue for histology, immunohistochemistry, and molecular biological research. In the last decade, the pathogenesis of pituitary adenomas has been extensively studied in humans, and to a lesser degree in dogs, and tumor oncogenesis has been studied in knock-out mice, often by means of quantitative reversed-transcriptase PCR (RT-qPCR). A precondition of such analyses is that so-called reference genes are stably expressed regardless of changes in disease status or treatment. In this study, the expression of six frequently used reference genes, namely, tata box binding protein (tbp), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide (ywhaz), hydroxymethylbilane synthase (hmbs), beta-2-microglobulin (b2m), succinate dehydrogenase complex subunit A (sdha), and glyceraldehyde 3 phosphate dehydrogenase 1 (gapdh), was studied in pituitary tissue (normal and adenoma) from three species (humans, mice, and dogs). The stability of expression of these reference genes differed between species and between healthy and diseased tissue within one species. Quantitative analysis based on a single reference gene that is assumed to be stably expressed might lead to wrong conclusions. This cross-species analysis clearly emphasizes the need to evaluate the expression stability of reference genes as a standard and integral aspect of study design and data analysis, in order to improve the validity of the conclusions drawn on the basis of quantitative molecular analyses

Expression stability of reference genes for quantitative RT-PCR of healthy and diseased pituitary tissue samples varies between humans, mice, and dogs

Pituitary surgery generates pituitary tissue for histology, immunohistochemistry, and molecular biological research. In the last decade, the pathogenesis of pituitary adenomas has been extensively studied in humans, and to a lesser degree in dogs, and tumor oncogenesis has been studied in knock-out mice, often by means of quantitative reversed-transcriptase PCR (RT-qPCR). A precondition of such analyses is that so-called reference genes are stably expressed regardless of changes in disease status or treatment. In this study, the expression of six frequently used reference genes, namely, tata box binding protein (tbp), tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein, zeta polypeptide (ywhaz), hydroxymethylbilane synthase (hmbs), beta-2-microglobulin (b2m), succinate dehydrogenase complex subunit A (sdha), and glyceraldehyde 3 phosphate dehydrogenase 1 (gapdh), was studied in pituitary tissue (normal and adenoma) from three species (humans, mice, and dogs). The stability of expression of these reference genes differed between species and between healthy and diseased tissue within one species. Quantitative analysis based on a single reference gene that is assumed to be stably expressed might lead to wrong conclusions. This cross-species analysis clearly emphasizes the need to evaluate the expression stability of reference genes as a standard and integral aspect of study design and data analysis, in order to improve the validity of the conclusions drawn on the basis of quantitative molecular analyses

Influence of macronutrient composition of commercial diets on circulating leptin and adiponectin concentrations in overweight dogs

Leptin and adiponectin play important roles in obesity-related inflammation and comorbidities. Previous research suggests that alterations in dietary macronutrient composition can modify circulating leptin and adiponectin concentrations in people, but limited research on this subject has been performed in dogs. This study investigated the effects of commercial high protein (HP), high fat (HF) and high carbohydrate medium protein (HCMP) diets on baseline (T-1 ) concentrations, post-prandial peak concentrations and total release in a ten-hour time span of leptin and adiponectin in dogs, when compared to a maintenance high carbohydrate low protein (HCLP) diet. Thirty-six overweight dogs were fed the HCLP diet in a one-week control period, after which the animals were assigned to one of three groups. In three four-week periods, each group was fed all test diets in a different sequence. At the last day of each period, blood was sampled at one hour before feeding (T-1 ) and at three (T3 ), six (T6 ) and nine (T9 ) hours after feeding. Feeding caused peak leptin concentrations at T6 and T9 (p < .001). No significant post-prandial change in adiponectin concentrations was found (p = .056). The HP diet resulted in lower leptin peak concentrations (p = .004) and AUCT-1-T9 (p = .01), but none of the diets influenced baseline leptin concentrations (p = .273). Baseline adiponectin concentrations were lower for the HF diet (p = .018) and HCMP (p < .001), and the HP, HF and HCMP AUCT-1-T9 (p < .001) were lower compared with the HCLP diet. Female dogs had lower adiponectin baseline concentrations (p = .041) and AUCT-1-T9 (p = .023) than male dogs. In conclusion, the HP diet was associated with the lowest post-prandial peak leptin concentration and the least decrease in adiponectin release, suggesting that a HP diet may improve immune-metabolic health and post-prandial satiety in overweight dogs

Inflammatory profiles in canine intervertebral disc degeneration

BACKGROUND: Intervertebral disc (IVD) disease is a common spinal disorder in dogs and degeneration and inflammation are significant components of the pathological cascade. Only limited studies have studied the cytokine and chemokine profiles in IVD degeneration in dogs, and mainly focused on gene expression. A better understanding is needed in order to develop biological therapies that address both pain and degeneration in IVD disease. Therefore, in this study, we determined the levels of prostaglandin E2 (PGE2), cytokines, chemokines, and matrix components in IVDs from chondrodystrophic (CD) and non-chondrodystrophic (NCD) dogs with and without clinical signs of IVD disease, and correlated these to degeneration grade (according to Pfirrmann), or herniation type (according to Hansen). In addition, we investigated cyclooxygenase 2 (COX-2) expression and signs of inflammation in histological IVD samples of CD and NCD dogs. RESULTS: PGE2 levels were significantly higher in the nucleus pulposus (NP) of degenerated IVDs compared with non-degenerated IVDs, and in herniated IVDs from NCD dogs compared with non-herniated IVDs of NCD dogs. COX-2 expression in the NP and annulus fibrosus (AF), and proliferation of fibroblasts and numbers of macrophages in the AF significantly increased with increased degeneration grade. GAG content did not significantly change with degeneration grade or herniation type. Cytokines interleukin (IL)-2, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, immune protein (IP)-10, tumor necrosis factor (TNF)-α, and granulocyte macrophage colony-stimulating factor (GM-CSF) were not detectable in the samples. Chemokine (C-C) motif ligand (CCL)2 levels in the NP from extruded samples were significantly higher compared with the AF of these samples and the NP from protrusion samples. CONCLUSIONS: PGE2 levels and CCL2 levels in degenerated and herniated IVDs were significantly higher compared with non-degenerated and non-herniated IVDs. COX-2 expression in the NP and AF and reactive changes in the AF increased with advancing degeneration stages. Although macrophages invaded the AF as degeneration progressed, the production of inflammatory mediators seemed most pronounced in degenerated NP tissue. Future studies are needed to investigate if inhibition of PGE2 levels in degenerated IVDs provides effective analgesia and exerts a protective role in the process of IVD degeneration and the development of IVD disease

Additional file 1: of Inflammatory profiles in canine intervertebral disc degeneration

A more detailed representation of included samples in addition to Table  1 in the original article. (DOCX 29 kb

Additional file 2: of Inflammatory profiles in canine intervertebral disc degeneration

Significant differences and confidence intervals of statistical analyses. (DOCX 25 kb

Intradiscal application of rhBMP-7 does not induce regeneration in a canine model of spontaneous intervertebral disc degeneration

INTRODUCTION: Strategies for biological repair and regeneration of the intervertebral disc (IVD) by cell and tissue engineering are promising, but few have made it into a clinical setting. Recombinant human bone morphogenetic protein 7 (rhBMP-7) has been shown to stimulate matrix production by IVD cells in vitro and in vivo in animal models of induced IVD degeneration. The aim of this study was to determine the most effective dose of an intradiscal injection of rhBMP-7 in a spontaneous canine IVD degeneration model for translation into clinical application for patients with low back pain. METHODS: Canine nucleus pulposus cells (NPCs) were cultured with rhBMP-7 to assess the anabolic effect of rhBMP-7 in vitro, and samples were evaluated for glycosaminoglycan (GAG) and DNA content, histology, and matrix-related gene expression. Three different dosages of rhBMP-7 (2.5 μg, 25 μg, and 250 μg) were injected in vivo into early degenerated IVDs of canines, which were followed up for six months by magnetic resonance imaging (T2-weighted images, T1rho and T2 maps). Post-mortem, the effects of rhBMP-7 were determined by radiography, computed tomography, and macroscopy, and by histological, biochemical (GAG, DNA, and collagen), and biomolecular analyses of IVD tissue. RESULTS: In vitro, rhBMP-7 stimulated matrix production of canine NPCs as GAG deposition was enhanced, DNA content was maintained, and gene expression levels of ACAN and COL2A1 were significantly upregulated. Despite the wide dose range of rhBMP-7 (2.5 to 250 μg) administered in vivo, no regenerative effects were observed at the IVD level. Instead, extensive extradiscal bone formation was noticed after intradiscal injection of 25 μg and 250 μg of rhBMP-7. CONCLUSIONS: An intradiscal bolus injection of 2.5 μg, 25 μg, and 250 μg rhBMP-7 showed no regenerative effects in a spontaneous canine IVD degeneration model. In contrast, intradiscal injection of 250 μg rhBMP-7, and to a lesser extent 25 μg rhBMP-7, resulted in extensive extradiscal bone formation, indicating that a bolus injection of rhBMP-7 alone cannot be used for treatment of IVD degeneration in human or canine patients

Intradiscal application of rhBMP-7 does not induce regeneration in a canine model of spontaneous intervertebral disc degeneration

INTRODUCTION: Strategies for biological repair and regeneration of the intervertebral disc (IVD) by cell and tissue engineering are promising, but few have made it into a clinical setting. Recombinant human bone morphogenetic protein 7 (rhBMP-7) has been shown to stimulate matrix production by IVD cells in vitro and in vivo in animal models of induced IVD degeneration. The aim of this study was to determine the most effective dose of an intradiscal injection of rhBMP-7 in a spontaneous canine IVD degeneration model for translation into clinical application for patients with low back pain. METHODS: Canine nucleus pulposus cells (NPCs) were cultured with rhBMP-7 to assess the anabolic effect of rhBMP-7 in vitro, and samples were evaluated for glycosaminoglycan (GAG) and DNA content, histology, and matrix-related gene expression. Three different dosages of rhBMP-7 (2.5 μg, 25 μg, and 250 μg) were injected in vivo into early degenerated IVDs of canines, which were followed up for six months by magnetic resonance imaging (T2-weighted images, T1rho and T2 maps). Post-mortem, the effects of rhBMP-7 were determined by radiography, computed tomography, and macroscopy, and by histological, biochemical (GAG, DNA, and collagen), and biomolecular analyses of IVD tissue. RESULTS: In vitro, rhBMP-7 stimulated matrix production of canine NPCs as GAG deposition was enhanced, DNA content was maintained, and gene expression levels of ACAN and COL2A1 were significantly upregulated. Despite the wide dose range of rhBMP-7 (2.5 to 250 μg) administered in vivo, no regenerative effects were observed at the IVD level. Instead, extensive extradiscal bone formation was noticed after intradiscal injection of 25 μg and 250 μg of rhBMP-7. CONCLUSIONS: An intradiscal bolus injection of 2.5 μg, 25 μg, and 250 μg rhBMP-7 showed no regenerative effects in a spontaneous canine IVD degeneration model. In contrast, intradiscal injection of 250 μg rhBMP-7, and to a lesser extent 25 μg rhBMP-7, resulted in extensive extradiscal bone formation, indicating that a bolus injection of rhBMP-7 alone cannot be used for treatment of IVD degeneration in human or canine patients