Development of a modified system of rat tail suspension as a model for osteopenia

• Grant number: 09/16832-0
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2010
• End date: July 31, 2012
• Field of knowledge: Engineering - Biomedical Engineering - Bioengineering
• Principal Investigator: José Batista Volpon
• Grantee: José Batista Volpon
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The rat tail suspension technique using a system of skin traction to study the effects of microgravity Is the most used animal model to study the effects of subloading that astronauts experience during space flights and, also, to study the effects of hypoactivity on the locomotor system. However, the skin traction is a technique that has limitations related to the length of time that the animal can stay in suspension and complications such as skin slough, venous and arterial compression and necrosis. Objective: to test a proposed modification of the tail suspension system using skeletal traction instead of skin traction and, therefore, to decrease the complication rate. Material and methods: young-adult female Wistar rats will be used and divided into 6 groups (n=10 animals for each group): Goup I - tail suspension with skin traction during 3 weeks; Group II - tail suspension with skeletal traction during 3 weeks; Group III - tail suspension with skin traction during 6 weeks; Group IV - tail suspension with skeletal traction during 6 weeks; Group V - animals without suspension, but with chow intake limited by the intake of suspended rats during 3 weeks; Group VI - animals kept in ordinary cages with no restriction of food and water for 6 weeks. Te suspended groups will be kept in special cages, suspended by the tail, and the non-suspended animal will be kept in ordinary cages. The observation will aim at evaluating the animal tolerance to both systems. After being killed the plasma cortisol level will be determined for the 3-week groups, the adrenal glands will be weighted and the stomach mucosa will be inspected for lesions as hyperemia, ulcers or scars to evaluate past and present stress conditions. The influence of both suspension methods on the skeleton will be analyzed by bone morphometry, mechanical testing and bone densitometry of the femurs, tibias and humerus. The working hypothesis is that the suspended animals with the skeletal traction will show a better tolerance for a longer period and with a lower rate of complications, with the same osteopenic effects on the long bones (AU)