Ultrastructure of the nucleus pulposus in the intervertebral disc after systemic administration of hydrocortisone in mice.

The nucleus pulposus of the lumbar intervertebral disc of mice given daily intramuscular injection of hydrocortisone at a dose of 1, 5, 10 mg/kg body weight for 1-4 weeks from 2 weeks of age was studied by electron microscopy. The hydrocortisone administration induced degeneration of the notochordal cells in the nucleus pulposus. The degenerative changes occurred earlier in the periphery of the nucleus pulposus than in the central region and developed earlier in mice treated with higher doses of hydrocortisone than in mice treated with lower doses. From the results, it is likely that steroid treatment accelerates the aging process of the nucleus pulposus and causes dysfunction of the intervertebral disc.