The effect of a nutritionally-balanced cassava ( Manihot esculenta Crantz ) diet on endocrine function using the dog as a model 1. Pancreas

Abstract

Growing dogs were divided into three groups and were fed on a control (rice) diet, a diet in which cassava ( Manihot esculenta Crantz; gari ) was used as the carbohydrate source, and the rice diet to which cyanide (equivalent to that present in gari) was added. Each group consumed its diet for 14 weeks, during which plasma thiocyanate concentration and plasma lipase ( EC 3.1.1.3) activity were monitored. Plasma free amino acids were determined from pooled samples taken at the end of the experimental period, and the insulin status of the dogs was evaluated using the gluconeogenic index. The dogs were killed and the pancreas examined for histopathology. Dogs fed on both gari diet and the rice+cyanide diet generated significant amounts of thiocyanate when compared with the controls, with the rice+cyanide group having higher plasma thiocyanate than the gari group ( P < 0.01). Plasma lipase activity rose significantly at the end of the experimental period in the dogs fed on gari ( P < 0.05). Gluconeogenesis from protein was greatest in the dogs fed on gari, five times greater than that in the control dogs, while gluconeogenesis from protein in the dogs fed on rice+cyanide was approximately twice as high as that of the control dogs. Histopathological examination of the pancreas showed haemorrhage, necrosis, fibrosis and atrophy of the acinar tissue and fibrosis of the islets of Langerhans in the dogs fed on gari. The pancreas of the dogs fed on rice+cyanide showed similar lesions but haemorrhage was not prominent and fibrosis was more marked. The present study indicated that a hypoinsulinaemia developed which was more severe in the animals fed on gari than in the dogs fed on the rice+cyanide diet and that the condition was not related to the level of plasma thiocyanate or the histopathology observed.