Endogenous versus exogenous glucocorticoid responses to experimental bacterial sepsis.

Although lack of adrenals dramatically reduces resistance against sepsis generally, the value of glucocorticoid levels above those normally produced by stress remains controversial. An early and long-held concept is that glucocorticoid protection against lipopolysaccharides in animal models is important. Supporting this concept, C3H/HeJ mice, lacking Toll-like receptor-4 (TLR-4), and consequently, endotoxin hyporesponsive, have recently been shown to be resistant to glucocorticoid protection against live Escherichia coli.

Long-term (6-wk) hindlimb suspension inhibits spermatogenesis in adult male rats.

The International Space Station will allow extended habitation in space and long-term exposure to microgravity (microG). A concern is the impact of long-term microG exposure on the ability of species to reproduce. The model often used to simulate microG is rat hindlimb suspension (HLS), where the hindlimbs are elevated above the cage floor with a tail harness.