432 CHONDROCYTE FUNCTION IS DISTURBED IN RATS WITH STUNTED GROWTH FOLLOWING NEONATAL X-IRRADIATION LIMITED TO THE HEAD

Abstract

Stunted growth after irradiation of the head only of the neonatal rat is unexplained. Prior studies show no relationship to food intake and no response to growth hormone and/or thyroxine. Male and female rats were X-irradiated with 600 rads limited to the head at 2 days of age. Controls were non-irradiated littermates. Irradiation resulted in retarded growth of body weight and tail length beginning prior to weaning; catch-up growth did not occur. Costal cartilage at ages 21 days (d), 40 d and 70 d was incubated 20 h at 37C in serum-free medium (M) consisting of phosphosaline buffer, pH 7.4, amino acids, glucose and antibiotics or in medium with 10 percent pooled normal rat serum (MS). ³⁵S-sulfate (S), ³H-thymidine (T), ¹⁴C-leucine (L) or ³H-proline (P) were added to media. In M irradiated rats had significantly increased incorporation of P at 21 d and 40 d and L at 40 d; there was no change in S. In MS irradiated rats had significantly increased incorporation of S and L at 21 d and 40 d. T incorporation was not increased over controls at any age in M or MS. We conclude that in stunted head-irradiated rats synthesis in cartilage of sulfated proteoglycans and collagen is increased and/or hyperresponsive to normal serum. That T incorporation is not increased is compatible with the possibility that failure in catch-up growth of bones after head irradiation results from inhibition of mitosis of chondrocytes.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD