Related Experiment Videos
Effects of perinatal high dose dexamethasone on skeletal muscle development in rats
J E Steiss1, J C Wright, N R Cox
1Scott-Ritchey Research Laboratory, College of Veterinary Medicine, Auburn University, Alabama 36849.
Insights
Dexamethasone (DEX) exposure in newborn and prenatal rats significantly reduced body weight and muscle mass, including soleus (SOL) and extensor digitorum longus (EDL) wet weight and SOL type I fiber diameter and number.
Area of Science:
- Biomedical Science
- Physiology
- Endocrinology
Background:
- Glucocorticoids, like dexamethasone (DEX), are potent anti-inflammatory drugs with known effects on growth and development.
- Prenatal and early postnatal exposure to corticosteroids can have long-lasting impacts on organ development and function.
Purpose of the Study:
- To investigate the effects of early-life dexamethasone (DEX) exposure on skeletal muscle development and growth in rats.
- To determine if postnatal or prenatal DEX administration impacts body weight, muscle wet weight, fiber morphology, and DNA content.
Main Methods:
- Two experiments were conducted: 1) Suckling rats received subcutaneous DEX or vehicle from day 3-7 postpartum. 2) Pregnant rats received DEX or vehicle on days 17-18 of gestation.
- Muscle tissues (soleus and extensor digitorum longus) were analyzed for wet weight, fiber type composition, fiber diameter, and DNA content.
- Body weight and muscle parameters were assessed at various time points up to day 60 postpartum.
Main Results:
- Postnatal DEX exposure significantly reduced body weight, soleus (SOL) and extensor digitorum longus (EDL) wet weight, and mean diameter of SOL type I fibers.
- Prenatal DEX exposure resulted in significantly lower body weight and reduced SOL wet weight and total number of SOL type I fibers.
- Trends for decreased total DNA in SOL and EDL were observed but did not reach statistical significance in either experiment.
Conclusions:
- Early-life exposure to dexamethasone (DEX), whether during suckling or gestation, negatively impacts growth and skeletal muscle development in rats.
- DEX administration leads to reduced body weight, muscle mass, and specific fiber characteristics, suggesting potential long-term consequences for muscle function.
Abstract:
Five litters of suckling rats were given either dexamethasone (DEX), 1 mg/kg, subcutaneously, three times daily (n = 4/litter) or vehicle control (n = 4/litter) from day 3 through day 7 after birth. Rats were weighed weekly and were weaned on day 30. On day 60, rats were killed and the soleus (SOL) and extensor digitorum longus (EDL) were removed for the following analyses: 1) wet weight, 2) light microscopic examination of hematoxylin and eosin stained transverse sections, 3) quantitative morphometric analysis of myosin ATPase stained transverse sections (fiber numbers, fiber type percentages and mean fiber diameters), and 4) DNA (total and mg/g wet weight). The following parameters were significantly reduced in treated rats: 1) body weight, 2) wet weight of SOL and EDL, and 3) mean diameter of SOL type I fibers. There was a trend for total DNA of SOL and EDL to be decreased in treated rats but this was not statistically significant. In a second experiment, pregnant rats (n = 4) were given DEX, 1 mg/kg, subcutaneously, twice daily, on days 17 and 18 of gestation. Two rats served as vehicle controls. The prenatally DEX-exposed rats weighed significantly less on weeks 3, 4, 6, 7 and 8. There were significant reductions in the following parameters for treated rats: 1) SOL wet weight, and 2) total number of SOL type I fibers. There was a trend for SOL DNA to be reduced but this was not statistically significant.