Effect of etretinate (aromatic retinoid) treatment during gestation and lactation periods on viability and somatic growth in F1 rats.

When female SD rats were continuously treated with Etretinate throughout pre-mating, gestation, and lactation periods, the resulting F1 pups exhibited low viability and inhibition of somatic growth after birth (Hummler et al., 1981). Nevertheless, these pups showed no notable change in body weight and external appearance at birth. We used the cross-fostering (between control and treated groups) method and investigate the neonatal viability and the growth hormonal changes in order to assess which treatment period of gestation or lactation was mainly involved in these effects and what changes were actually induced in the F1 pups. The results showed that low viability and inhibition of somatic growth after birth were mainly related to treatment during the gestation period, and these effects were augmented by treatment during the lactation period. Serum GH and IGF-I levels were increased on day 21 in F1 pups groups in which inhibition of somatic growth was observed. These results indicated that treatment with Etretinate during the gestation period might induce a decrease in the number of receptors of GH and IGF-I or other changes, such as a poor-response in target tissues due to a down-regulation, with an increase of serum GH and IGF-I levels.