Composition of Dietary Fat Affects Blood Pressure and Insulin Responses to Dietary Obesity in the Dog

Abstract

Cardiovascular and metabolic parameters were evaluated in 15 female spayed dogs before and after they became obese on either a saturated fat (LD, lard, n=8) or unsaturated fat (CO, corn oil, n=7) diet. Body weight and body fat increased significantly in both groups, although no differences occurred between diet groups. Dogs receiving the LD diet exhibited a greater increase in mean arterial pressure than those receiving the CO diet (pc0.01; 15.9 f 2.1 vs. 9.8 f 3.3 mm Hg increase). The CO diet stimulated a greater increase in heart rate than the LD diet (pc0.05; 32.8 f 7.8 vs. 14.1 i 5.8 bpm increase). Ganglionic blockade with chlorisondamine caused an increase in HR in both lean groups and in the obese CO group, but not the obese LD group, consistent with a decrease in parasympathetic tone to the heart in the dogs overfed saturated fat. Obesity enhanced the heart rate response to P-adrenergic stimulation by isoproterenol in the LD, but not CO group. The LD diet increased circulating insulin and decreased insulin sensitivity, whereas the CO diet had no effect on either parameter. These findings suggest that the composition of dietary fat can modulate the autonomic and metabolic adaptations induced by dietary obesity. 1998;6: 137-146.~~ ~ ~

Impaired Atrial M 2 -Cholinoceptor Function in Obesity-Related Hypertension

“…7 However, the early aspect (eg, before 5 weeks of HFD) of this decrease and its links with both food intake and the free fatty acid plasma levels suggest an important initial role of parasympathetic tone in the physiopathological mechanism of obesityrelated hypertension. 9,10 This decrease in parasympathetic tone could reduce the capacity of the autonomic nervous system to buffer BP changes. Endogenous catecholamines are able to downregulate M 2 -cholinoceptors.…”

“…4,5 In a model obtained with the use of a high-fat diet (HFD), 6 various abnormalities have been reported that can explain the increase in BP, such as renal 4 or autonomic nervous system dysfunctions. [7][8][9][10] As observed in obese humans, [11][12][13] some authors have reported an increase in sympathetic nervous activity during weight gain in dogs. 8,10,14 Moreover, a decrease in the parasympathetic drive to the heart has been reported in obese humans 15,16 and in obese dogs.…”

Canine diabetes mellitus: can old dogs teach us new tricks?

“…Obesity can cause hyperinsulinaemia and glucose intolerance [5] and the effects of insulin resistance appear to be particularly pronounced in dogs fed a diet which is high in saturated fat [52]. Some obese dogs with a fasting hyperinsulinaemia are still able to increase insulin secretion upon intravenous glucose administration, whereas others fail to do so [52]. Although obesity is common in the UK dog population and clearly influences the animal's ability to utilise glucose, progression to overt diabetes has yet to be documented.…”

Effects of Genetic and Diet‐Induced Obesity on Lipid Metabolism

“…Thesecafeteria-fed animals in previous studies have demonstrated increased body weight and metabolic changes that favour an increase of fat accumulation. Dietary fat is poorly regulated; that is, excessive intake of fat at one meal is not followed by decreased intake at the next meal (3). Fat in the diet increases the palatability of food, as well as having a higher energy density than carbohydrates and proteins.…”