Postnatal evolution of supernumerary ribs in rats after a single administration of sodium salicylate

Abstract

Radiographs were used to follow the postnatal evolution of 14th ribs in rat pups. Initially, 30 pregnant female rats were randomly distributed into two groups receiving 0 or 300 mg kg ؊1 sodium salicylate on day 9 of pregnancy. In the treated group, adverse effects were noted on body weight changes and food consumption during the 2 days following dosing. At birth, a high majority of pups had extra ribs at the 300 mg kg ؊1 dose. Radiographs done on postnatal days 1, 6, 14, 28 and 54 showed a reduction in the incidence of rudimentary ribs only, whereas extra ribs, often associated with 27 presacral vertebrae, had the same incidence from birth to adult stage. Furthermore, extra ribs seemed to exhibit similar growth evolution to the other thoracic ribs. This work helps to clarify the postnatal evolution of supernumerary ribs because it was performed on the same animals from birth to adult stage, showing that the reversibility was related to rib length and, in consequence, concerned the rudimentary ribs only. The coexistence of additional presacral vertebrae primarily with extra ribs suggests that both kinds of supernumerary ribs (rudimentary and extra) might be different phenomena and could be considered separately in developmental toxicology studies.

Chemically induced supernumerary lumbar ribs in CD‐1 mice: Size distribution and dose response

“…Wickramaratne (1988) demonstrated that salicylate‐induced SNR induced in rats were transient, becoming part of the transverse process of the first lumbar vertebra. However, Foulon et al (2000) followed the fate of salicylate‐induced SNR in rats by radiography from birth to adulthood, and reported that while “rudimentary” SNR (defined as less than half the length of the thirteenth rib [Kimmel and Wilson, 1973]) were transient, the incidence of offspring with “extra” SNR (greater than half the length of the thirteenth rib) was the same at birth and adulthood. We have reported that fetal SNR induced in rats by the herbicide bromoxynil appeared to be transient, while in contrast, some bromoxynil‐induced SNR in mice appeared to persist postnatally (Chernoff et al, 1991; Rogers et al, 1991).…”

“…We have reported that fetal SNR induced in rats by the herbicide bromoxynil appeared to be transient, while in contrast, some bromoxynil‐induced SNR in mice appeared to persist postnatally (Chernoff et al, 1991; Rogers et al, 1991). In agreement with the results of Foulon et al (2000), bromoxynil‐induced SNR in rats were mostly rudimentary, while those that persisted in mice were extra SNR. Beck (1983) reported that SNR induced prenatally by acetazolamide also persist to adulthood in mice.…”

Fibromuscular dysplasia of the coronary and renal arteries?

“…Skeletal examinations revealed no abnormalities in any treated groups but some variations, by far the most prominent of which was significantly increased occurrence of lumbar rudimentary ribs at 1,000 mg/kg/day relative to control (25/131, 19.1%). The increase was still within the historical control range (1.1–21.2%), and several references provided discuss the transient nature of rudimentary ribs in rodent toxicity studies (e.g., Chernoff et al, 1991; Foulon et al, 2000). According to the translated text, incidences of all abnormalities and variations observed were either not statistically significant relative to vehicle controls, not dose related, within the range of historical controls, or known to be transient and reversible upon further maturation.…”

Developmental toxic effects of N‐ethyl‐2‐pyrrolidone administered orally to rats

“…An increased incidence of supernumerary 14th ribs was observed at 250 mg kg −1 day −1 and higher doses. Rudimentary supernumerary ribs, which were shown to be mostly reversible during postnatal life (Chernoff et al, 1991;Foulon et al, 2000), were predominant at 250 mg kg −1 day −1 . Thus, the no-observed-adverse-effect level (NOAEL) no changes in the incidence of 27 presacral vertebrae in any treated group.…”