Cardiac disease is linked to adiposity in male gorillas (Gorilla gorilla gorilla)

Abstract

Cardiac disease is a major cause of morbidity and mortality for adult gorillas. Previous research indicates a sex-based difference with predominantly males demonstrating evidence of left ventricular hypertrophy. To evaluate these findings, we analyzed serum markers with cardiac measures in a large sample of gorillas. The study sample included 44 male and 25 female gorillas housed at American Association of Zoo and Aquariums (AZA)-accredited zoos. Serum samples were collected from fasted gorillas during routine veterinary health exams and analyzed to measure leptin, adiponectin, IGF-1, insulin, ferritin, glucose, triglycerides, and cholesterol. Cardiac ultrasonography via transthoracic echocardiogram was performed simultaneously. Three echocardiographic parameters were chosen to assess cardiac disease according to parameters established for captive lowland gorillas: left ventricular internal diameter, inter-ventricular septum thickness, and left ventricular posterior wall thickness. Our data revealed that high leptin, low adiponectin, and lowered cholesterol were significantly and positively correlated with measures of heart thickness and age in males but not in females. Lowered cholesterol in this population would be categorized as elevated in humans. High leptin and low adiponectin are indicative of increased adiposity and suggests a potential parallel with human obesity and cardiovascular disease in males. Interestingly, while females exhibited increased adiposity with age, they did not progress to cardiac disease.

Fig 1. The significant variables for principal component 1 plotted against heart measures.

Leptin, adiponectin and cholesterol are each plotted against heart measures LVID, IVS, and LVPW. For males, principal component 1 was significantly correlated with heart measures IVS and LVPW. Males that were previously diagnosed with heart disease are indicated by red circles, healthy males are depicted by black circles and females by white circles.

Fig 2. The significant variables for principal component 1 plotted against age and age plotted against heart measures.

Leptin, adiponectin and cholesterol are each plotted against age. For males, principal component 1 was significantly correlated with age. Age is also plotted against each heart measure. Males that were previously diagnosed with heart disease are indicated by red circles, healthy males are depicted by black circles and females by white circles.