Functional consequence of exposure to dieldrin on mammary development and function.

The effect of dieldrin (Dln) on the development of the mammary gland and on functional parameters of CID-9 mammary cells in culture was investigated. One-month-old Sprague-Dawley female rats were bred and received intraperitoneal injection with 2.5 or 15 microM Dln during the last trimester of their gestation. Mammary glands of 15-microM Dln-treated rats showed immature alveolar structures by day 18 of gestation and abundant adipose tissue. Dln-treated rats had a lower number of pups, and the weight of pups between days 14 and 31 of age compared with non-treated rats was significantly lower. Long-term exposure of CID-9 mammary cells, cultured under non-differentiation conditions, on plastic, or under differentiation permissive conditions, dripped with EHS-matrix, to 5 or 25 microM Dln was detrimental to cell growth. The short-term effect of Dln exposure (up to 9 h) on CID-9 cells, under the same culture conditions, did not affect their beta-casein mRNA levels, but induced apoptosis, down regulated gap junction intracellular communication and induced IL-6 and TNF-alpha expression.

Effects of ultrasound-guided transvaginal follicular aspiration on oocyte recovery and hormonal profiles before and after GnRH treatment.

Endocrine changes and recovered oocytes were evaluated during 16 wk of ultrasound-guided transvaginal follicular aspiration (TVFA) and prior to and following administration of GnRH at the cessation of aspiration. Nonlactating previously aspirated (PAC, n = 4) and non-aspirated, (AC, n = 4) Holstein cows were subjected to 16 wk of twice-weekly aspiration. Four control cows (OAC) were aspirated 1 time only at the final TVFA session (wk 16). Jugular blood samples were collected from all cows during aspiration, before and after the final TVFA session, and during an 18-d period following cessation of aspiration. Ovarian activity was monitored in all cows after cessation of aspiration for 18 d. The PAC and AC cows averaged 3.4 +/- 1.2 (+/- SE) and 6.8 +/- 1.2 oocytes per session, respectively. Progesterone concentrations during TVFA did not differ between the PAC and AC (0.8 +/- 0.1 and 0.9 +/- 0.1 ng/mL, respectively). Progesterone concentration in OAC was 4.5 +/- 0.2 ng/mL before TVFA, while the PAC and AC averaged 0.5 +/- 0.2 and 0.3 +/- 0.2 ng/mL, respectively, at 16 wk. At Week 16 LH was 1.0 +/- 0.2 ng/mL and it increased to 7.5 +/- 0.1 ng/mL after GnRH treatment. The LH concentration before the final aspiration session was higher at peak amplitude in PAC than in AC groups and peak length was longer in OAC than in AC cows (P < 0.07). Between 18 and 24 h after the last aspiration there were more LH peaks and greater peak frequencies in PAC than in OAC cows (P < 0.07), and the interval between peaks was longer in PAC and AC cows (P < 0.10) than in OAC cows. Mean FSH concentrations were lower (P < 0.01) for OAC than for PAC and AC groups at 20 and 24 h after the last aspiration. Follicle numbers after GnRH varied most among treatment groups for follicles < 9 mm, with the PAC, AC and OAC averaging 5.1 +/- 1.0, 5.1 +/- 1.0, and 3.8 +/- 1.0 follicles/d, respectively. Progesterone concentrations increased to 1.1 +/- 0.3 ng/mL in PAC cows and 2.5 +/- 0.3 and 3.4 +/- 0.3 ng/mL in AC and OAC groups, respectively, during the 18-d period. These results suggest that long-term TVFA affects progesterone, LH and FSH profiles and ovarian dynamics in cows.

Effect of intrauterine position of conceptus development, placental and endometrial release of progesterone and estrone in vitro, and concentration of steroid hormones in fetal fluids throughout gestation in swine.

Twenty intact and 25 unilaterally hysterectomized-ovariectomized gilts were used to study the effect of fetal intrauterine position on conceptus development, concentrations of endogenous progesterone (P4) and estrone (E1) in the placenta and endometrium, and steroid hormone concentrations in amniotic and allantoic fluids during gestation. Gilts were hysterectomized at 40, 60, 80, or 100 d of gestation. Placental and endometrial tissues were pooled individually by the intrauterine position of the associated fetus and incubated separately, and concentrations of P4 and E1 in the medium were determined. Uterine status (intact or unilaterally hysterectomized-ovariectomized) did not affect any of the variables measured. Intrauterine position affected fetal and placental weights (P < 0.02 and 0.01, respectively) only at Day 40 of gestation. The weights of female fetuses bordered in utero by two males and their associated placentas were lower than those from other intrauterine positions. Intrauterine position had no effect on placental and endometrial P4 release or on E1, P4, and androgen concentrations in fetal fluids at any stage of gestation. At Day 100 of gestation, placentas associated with fetuses bordered by those of the same sex released more E1 than did placentas associated with fetuses bordered by those of the same opposite sex (P < 0.01). This study indicates that intrauterine position in swine has a limited effect on conceptus development and on placental and endometrial steroidogenic activity.

Effect of uterine space and fetal sex on conceptus development and in vitro release of progesterone and estrone from regions of the porcine placenta throughout gestation.

Intact (n = 17) and unilaterally hysterectomized-ovariectomized (UHOX, n = 19) gilts were used to study conceptus development and the steroidogenic capability of three regions of the porcine placenta under normal and crowded intrauterine conditions. Gilts were hysterectomized on either Days 30, 50, 70, or 90 of gestation. Placentas were combined according to the sex of the fetus associated with the placental unit, except at Day 30, when all were combined. Placentas were cut into three regions: middle, inner, and polar. Placental tissues were incubated for 0, 1, 5, and 3 hr, and concentrations of progesterone (P4) and estrone (E1) in the incubation medium were determined. Fetal survival rate was greater (P < 0.01, 0.05, and 0.001 at days 50, 70, and 90, respectively) in intact than in UHOX gilts. Placental length and weight, fetal length and weight, and allantoic fluid volume were greater (P < 0.05, 0.001, 0.05, and 0.001, respectively) in intact than in UHOX gilts. P4 concentration was lower (P < 0.001, 0.002, and 0.001 at Days 50, 70, and 90, respectively) in the incubation medium of polar region placenta compared with the other regions. The release of P4 was greater (P < 0.005) from the placentas of intact versus UHOX gilts at Day 90 but was not different at Days 30, 50, or 70. The sex of the fetus did not affect placental P4 release. The region of the placenta affected E1 release at Day 30 (P < 0.01, greater in polar section) and Day 50 (P < 0.06, less in polar section). There was no effect of uterine status on E1 release.(ABSTRACT TRUNCATED AT 250 WORDS)