Abstract
The mechanism of deciduomata maintenance by 3‐methylcholanthrene (MCA) was investigated in normally cycling Sprague‐Dawley rats. Animals received daily injections of ovine prolactin (LTH) from days 1‐4 following estrus (pre‐trauma period). On days 5 to 8 (post‐trauma period), each rat received either daily injections of LTH, sesame oil intragastrically, or 10 mg 3‐methylcholanthrene (MCA) in 1 ml sesame oil intragastrically. Other rats were either adrenalectomized, ovariectomized or hypophysectomized at the time of uterine traumatization on day 4. Results showed that rats which were not treated with LTH but in which the uterus was traumatized did not develop deciduomata, whereas 80% of rats treated with 5 IU LTH during the post‐trauma period were positive. Rats receiving 10 IU LTH during the pre‐trauma period but untreated during the post‐trauma period did not develop deciduomata. However, 27% of rats were positive when fed oil during the post‐trauma period. In the second experiment, 1 ml oil prior to and during the pre‐trauma period resulted in all negative responses when oil was fed during the post‐trauma period. All rats receiving LTH during the pre‐trauma period followed by MCA during the post‐trauma period were positive. None of the ovariectomized or hypophysectomized rats exhibited deciduomata when treated with MCA during the post‐trauma period. However, 75% of the adrenalectomized rats showed positive reactions. These data indicated that MCA effects release of progestin in quantities sufficient to maintain deciduomata and that both the pituitary gland and ovary are essential for this reponse.