Expression of caspases 3 and 8 in spleen and thymus of immunosuppressed rats was analyzed by the reverse transcriptase-polymerase chain reaction (RT-PCR). Forty-five weaned female Wistar rats were divided into three groups: A (n=18) and B (n=18) rats were injected with 250µg and 500µg per rat, respectively; and C (n=9) rats were non-treated control animals. After 24, 48 and 72 hours, six animals from A and B groups and three controls were anaesthetized with chloroform, weighed and euthanized. Thymus and spleens were collected, weighed and a sample of each organ was fixed by immersion in 10% buffered formaline and embedded in paraffin. Thin sections (5µm) were stained with HE. Thymus and spleen samples were snap frozen in liquid nitrogen and stored at -80ºC for total RNA and DNA extraction. Apoptotic indices were calculated using sections stained with HE. Apoptotic indices and organs weights showed that hypotrophy happened mainly at 72h post treatment with 500µg/rat. RT-PCR was standardized using a pool of control animals and another from treated animals with A and B doses at each time period, respectively. Specific oligonucleotides for caspases 3 and 8 were drawn to obtain fragments of 271bp and 368bp, respectively. The results demonstrated that technique RT-PCR is sensitive enough to detect caspases 3 and 8 mRNAs and that caspase 3 and 8 participate in the apoptotic process induced by dexamethasone in weaned rats.
rat; apoptosis; dexamethasone; thymus; spleen; caspase 3; caspase 8; RT-PCR
