Date of Award

Summer 1980

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Gerald J. Pepe

Committee Member

R. James Swanson

Committee Member

Lloyd Wolfinbarger, Jr.

Call Number for Print

Special Collections LD4331.B46 C536

Abstract

It has been previously demonstrated that 7,12-dimethylbenz(a) anthracene (DMBA) is an initiator of ovarian granulosa cell tumors. It is also known that DMBA leads to destruction of primordial oocytes, and that tumor induction may involve the interaction of pituitary gonadotropins. However, the effects of DMBA on ovarian steroidogenesis and uterine growth in relation to the tumorigenic process have not been investigated. Therefore, the present study was conducted to examine these parameters using adult C57Bl/6N mice treated in proestrus and diestrus II with 0.1 ml corn oil with or without 1.5 mg DMBA and killed 44 hours later. The uteri and ovaries were removed, weighed, and homogenized in cold Tris buffer (pH 7.4). The total uterine cytosolic estrogen receptor concentration was assayed using the tritium exchange technique. Ovarian steroidogenesis was determined in-vitro by incubating (37° C; 60 min) ovarian homogenates in tubes containing [7- 3H] pregnenolone or [l,2- 3 H] testosterone.

In control animals, both ovarian and uterine weights were greater in estrus than in metestrus, and this weight difference between days of the cycle was maintained in DMBA treated mice. However, uterine weight in estrus was significantly lower in DMBA treated mice than in control mice. However, the total estrogen receptor concentration of DNBA treated mice measured in estrus was significantly lower than control mice. This was not the case for metestrous mice treated with DMBA. The conversion of pregnenolone to progesterone in control animals was greater in metestrus than in estrus, in contrast, the production of estradiol was greater in estrous mice than in metestrus control animals. Treatment with DNBA did not alter ovarian steroidogenesis.

The reduction in uterine weight observed in estrous mice treated in diestrus II with DNBA is probably the result of DMBA or a metabolite &f DMBA blocking the synthesis of the cytosolic estrogen receptor. It would appear that the effects of DNBA are not mediated via an alteration of ovarian steroid-producing enzymes and is also probably not due to an alteration of hepatic enzymes regulating estradiol and/or progesterone degradation.

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DOI

10.25777/gvx2-1w91

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