Histologic changes in the adrenal cortex from young rats following spaceflight

Area of Science:

• Spaceflight physiology
• Animal models in research
• Histopathology

Background:

• Spaceflight presents numerous physiological stressors including microgravity and confinement.
• Understanding these stressors' effects on endocrine organs is crucial for astronaut health.

Purpose of the Study:

• To investigate the histological impact of spaceflight on the adrenal glands of young rats.
• To differentiate spaceflight effects from confinement stress.

Main Methods:

• Young male rats were exposed to a 17-day space shuttle flight (STS-78) in an Animal Enclosure Module (AEM).
• Ground controls included baseline, AEM-housed, and vivarium groups.
• Adrenal glands were collected post-flight for light microscopy analysis.

Main Results:

• Flight group rats exhibited greater adrenal weights and zona fasciculata width compared to controls.
• Histological analysis revealed increased parenchymal cord-like formation, depleted cytoplasmic lipids, and enlarged nuclei in the zona fasciculata of flight animals.
• Adrenal glands from AEM-housed controls showed some cortical changes, suggesting confinement stress.

Conclusions:

• Spaceflight induced adrenal enlargement and significant histological alterations in rats.
• Confinement within the AEM may contribute to observed adrenal changes.
• Combined effects of spaceflight, re-entry, and confinement likely caused the observed adrenal pathology.