Effects of prostaglandin F2 alpha (PGF2 alpha) on secretion of pregnancy specific protein B (PSPB) and placentome weights in intact or ovariectomized 90 to 100 day pregnant ewes.

Vehicle or 8 or 16 mg PGF2 alpha/58 kg/body weight (BW) was given intramuscularly to intact or ovariectomized 90 to 100 day pregnant ewes in two separate experiments. Treatment with 8 mg PGF2 alpha in intact 90 to 100 day pregnant ewes increased (P < or = 0.05) placentome weights, but not in ovariectomized 90 to 100 day pregnant ewes (P > or = 0.05). Concentrations of PSPB in uterine venous plasma of control 90 to 100 day intact pregnant ewes over the 72 hour sampling period averaged 52 +/- 5 ng/ml. Profiles of PSPB in uterine plasma in the 16 mg PGF2 alpha/58 kg/BW-treated ewes differed (P < or = 0.05) from control or 8 mg PGF2 alpha-treated 90 to 100 day intact pregnant ewes. Pregnancy specific protein B was increased (P < or = 0.05) at 64 hr in intact 90 to 100 day pregnant ewes by treatment with 8 mg PGF2 alpha/58 kg/BW. There was a quadratic increase (P < or = 0.09) in PSPB in uterine venous plasma of all three treatment groups of intact 90 to 100 day pregnant ewes. Concentrations of PSPB in uterine venous plasma of control 90 to 100 day ovariectomized pregnant ewes over the 72 hr treatment period averaged 90 +/- 5 ng/ml. Profiles of PSPB did not differ among the vehicle, 8 mg PGF2 alpha or 16 mg PGF2 alpha-treated ovariectomized 90 to 100 day pregnant ewes. There was a quadratic increase (P < or = 0.10) in PSPB in uterine venous plasma of ovariectomized 90 to 100 day pregnant ewes treated with 8 or 16 mg PGF2 alpha/58 kg/BW. It is suggested that PSPB may have a role in regulating placental steroidogenesis.

Effects of prostaglandin F2 alpha (PGF2 alpha) on secretion of estradiol-17 beta and cortisol in 90 to 100 day hysterectomized, intact and ovariectomized pregnant ewes.

Vehicle or 8 or 16 mg PGF2 alpha/58 kg/body weight (BW) was given intramuscularly to intact, hysterectomized and ovariectomized 90 to 100 day pregnant ewes in three separate experiments. Hysterectomy alone decreased (P < or = 0.05) estradiol-17 beta in jugular venous blood by 80 percent within 16 hours and profiles of estradiol-17 beta did not differ (P > or = 0.05) among vehicle or 8 or 16 mg PGF2 alpha/58 kg/BW-treated ewes. Profiles of estradiol-17 beta differed (P < or = 0.05) in intact pregnant ewes treated with 8 or 16 mg PGF2 alpha/58 kg/BW when compared to controls and in ovariectomized (P < or = 0.10) 90 to 100 day pregnant ewes treated with 16 mg PGF2/58 kg/BW. Estradiol-17 beta decreased (P < or = 0.05) over time in vehicle and 8 mg PGF2 alpha/58 kg/BW-treated intact and in vehicle-treated ovariectomized 90 to 100 day pregnant ewes. Cortisol decreased (P < or = 0.05) over time in hysterectomized, intact, and ovariectomized 90 to 100 days pregnant ewes, but did not differ (P < or = 0.05) among vehicle or 8 or 16 mg PGF2 alpha/58 kg/BW-treated ewes. It is suggested that estradiol-17 beta has a role in regulating ovine placental steroidogenesis.

Effect of prostaglandin F2 alpha on uterine or ovarian secretion of prostaglandins E and F2 alpha in vivo in 90-100 day hysterectomized, intact or ovariectomized pregnant ewes.

Vehicle or 8 or 16 mg of PGF2 alpha per 58 kg body weight was given intramuscularly to intact, hysterectomized or ovariectomized 90-100 day pregnant ewes in three separate experiments. Both doses of PGF2 alpha increased PGF2 alpha in ovarian venous plasma compared with controls at 72 hr post treatment in intact (P < or = 0.05) but did not in hysterectomized (P > or = 0.05) 90-100 day pregnant ewes. Concentrations of PGE in ovarian venous blood of intact ewes did not differ (P > or = 0.05) between treatment groups and were equivalent to concentrations of PGE determined in uterine venous plasma. PGE was decreased in ovarian venous plasma by PGF2 alpha in hysterectomized ewes (P < or = 0.07). PGE in uterine venous plasma averaged 6 ng/ml over the 72-hr treatment period in intact and ovariectomized 90-100 day pregnant ewes and was 12 fold greater (P < or = 0.05) than PGF2 alpha which averaged 500 pg/ml in uterine venous plasma. Both PGF2 alpha and PGE increased (P < or = 0.05) by 64 hr in uterine venous plasma of the 8 mg PGF2 alpha-treated intact pregnant ewes. A significant quadratic increase (P < or = 0.05) was observed for PGF2 alpha and PGE in the vehicle and both PGF2 alpha treatment groups of intact ewes at the end of the 72-hr sampling period. It is concluded that the uterus and ovaries secrete significant quantities of PGF but little PGF2 alpha during midgestation. In addition, PGF2 alpha increased uterine secretion of PGE in vivo. PGE may be a placental stimulator of ovine placental secretion of progesterone or PGE may protect placental steroidogenesis from actions of PGF2 alpha.

Effects of the purine biosynthesis pathway inhibitors azaserine, hadacidin, and mycophenolic acid on the developing ovine corpus luteum.

De novo synthesis precursors of the purine second messengers adenosine, guanosine and inosine are adenosine, guanosine and inosine monophosphate (AMP, GMP, IMP), respectively. Inhibitors of the de novo purinergic synthesis pathways for AMP, GMP and IMP by hadacidin, mycophenolic acid and azaserine, respectively, or adenosine, guanosine or inosine alone or in combination were given every 4 or 6 hours in vivo. Treatments were given into the ovarian vascular pedicle sheath adjacent to the luteal-bearing ovary in three separate experiments to determine whether purines were involved in development of the corpus luteum. Hadacidin lowered AMP (p < or = 0.01) and azaserine tended to lower IMP and the GMP: AMP ratio (p < or = 01) while mycophenolic acid tended to lower the GMP:AMP ratio (p < or = 0.1) in luteal tissue. Azaserine (150 mg) increased progesterone (p < or = 0.01) on some days but guanosine or inosine had no effect on profiles of progesterone in jugular blood of the developing corpus luteum (p > or = 0.1). Azaserine (500 micrograms) tended to lower progesterone in jugular blood (p < or = 0.1) while profiles of progesterone did not differ among guanosine or inosine or adenosine, guanosine and inosine plus hadacidin, mycophenolic acid and azaserine treatment groups compared to controls (p > or = 0.1). Weights of corpora lutea or composition of cell types in the corpus luteum or their viability were not affected by adenosine, guanosine, inosine, hadacidin, mycophenolic acid or azaserine (p > or = 0.1). Since profiles of jugular progesterone did not differ between treatments during development of the corpus luteum, these results suggest that progesterone production by the developing corpus luteum is a) less dependent on de novo synthesized purines or b) there may be a non-purinergic-dependent second messenger system controlling biosynthesis of steroids in the developing ovine corpus luteum.

Effect of prostaglandin F2 alpha (PGF2 alpha) on sources of progesterone and pregnancy in intact, ovariectomized and hysterectomized 90-100 day pregnant ewes.

A single dose of 8 or 16 mg of PGF2 alpha per 58 kg body weight was injected intramuscular into intact, ovariectomized or hysterectomized 90-100 day pregnant sheep in three separate experiments. Both doses of PGF2 alpha decreased the weights of the corpora lutea (P less than or equal to 0.05) and the concentration of progesterone in ovarian venous plasma at 72 hr (P less than or equal to 0.05) compared to the 0 hr sample within treatment groups and to control ewes at 72 hr in intact and hysterectomized pregnant ewes. In hysterectomized pregnant ewes, progesterone in jugular plasma declined (P less than or equal to 0.05) from 0 to 72 hr but never fell below 4 mg/ml and this decrease in progesterone after 8 or 16 mg PGF2 alpha was greater than in control hysterectomized ewes (P less than or equal to 0.05). There was a significant decrease in progesterone over time in jugular or uterine venous plasma in the presence of absence of the ovaries in 90-100 day pregnant ewes (P less than or equal to 0.05) but the profiles of progesterone were not different between vehicle and PGF2 alpha-treated ewes (P greater than or equal to 0.05). Uterine venous progesterone never declined below 30 ng/ml in the presence or absence of the ovaries and there was a significant quadratic increase (P less than or equal to 0.05) in uterine venous progesterone toward the end of the 72 hr sampling period indicating an increase in steroidogenic activity of the placenta. PGF2 alpha did not affect the number of abortions in intact or ovariectomized pregnant ewes (P greater than 0.05). Thus, the corpus luteum of sheep at 90-100 days of pregnancy is functional and responsive to PGF2 alpha, placentomes are functional but do not appear to be responsive to the doses of PGF2 alpha tested and PGF2 alpha was not an abortifacient over the 72 hr treatment period.

Cytophotometric analysis of T-2 toxin induced alterations in chromatin condensation and neuronal nuclear volume of rat supraoptic-magnocellular neurons.

Quantitative cytophotometry and ocular filar micrometry were used to monitor T-2 toxin induced alterations in chromatin and neuronal nuclear volume in supraoptic-magnocellular neurons of rat hypo-thalami. Thirty male Sprague-Dawley rats (200-220g) were given a single i.p. injection of T-2 toxin (0.5, 0.75, 1.0 and 1.5 X LD50), a trichothecene mycotoxin; rats were decapitated 8 hours post-dosing. After stoichiometric Feulgen-DNA staining of brain sections, scanning-integrating microdensitometry was used to quantify changes in the susceptibility of chromatin to Feulgen acid hydrolysis. Changes in neuronal nuclear volumes were also determined histometrically. Within the magnocellular neurons of the supraoptic nuclei, significant reductions in F-DNA reactivity were observed in the 0.5, 0.75, and 1.0 X LD50 groups (i.e. 3.7%, 4.4% and 2.5%, respectively); however, rats receiving 1.5 X LD50 T-2 toxin showed no difference in F-DNA reactivity compared to controls. In addition, ocular filar micrometry demonstrated increased neuronal nuclear volumes in all groups receiving T-2 toxin, and following an inverse trend to that seen with F-DNA stainability. Additional observations included pronounced polydipsia, polyphagia and horripilation in the experimental groups, independent of the dosages employed; these changes were evident within 1 hour post-injection. It is postulated that the T-2 toxin induced reduction in the susceptibility of chromatin to Feulgen acid hydrolysis and concomitant increases in neuronal nuclear volumes represent an early indication of impaired metabolic activity. Since these neurons are important sites of vasopressin (antidiuretic hormone) synthesis, these data suggest an impaired osmoregulatory ability. The pronounced polydipsia which occurred shortly after intoxication is further evidence of this impairment. Although these findings do not provide insight relating to the mechanism of osmoregulatory disruption, it is evident that an impaired ability to osmoregulate is among the earliest indications of acute T-2 toxin mycotoxicosis.

Cytophotometric assessment of granulosa cell protein and nucleic acid levels during the estrous cycle in rats treated with T-2 toxin.

Female Sprague-Dawley rats (160-180g.) with normal estrous cyclicity established by vaginal smears, were injected intraperitoneally with 0.45 mg/kg (low dose) or 0.68 mg/kg (high dose) of T-2 toxin, a trichothecene with potent protein inhibitory abilities. Control animals were injected with only the 100% ethanol vehicle. All animals were decapitated at 8 hours post-exposure, and their ovaries removed and processed for paraffin sectioning. Coomassie, Feulgen, and azure B/DNase staining procedures were used to show granulosa cell protein levels, F-DNA stainability, and basophilia/RNA levels, respectively. Quantification of these parameters was accomplished using scanning-integrating microdensitometry. T-2 toxin treatment groups had granulosa cell protein levels significantly lower than those of the control animals. However, rats exposed to the lower dose of T-2 toxin generally showed a more marked suppression of protein levels than the high dose group, regardless of the stage of the estrous cycle. In addition, rats that received lower doses of T-2 toxin had impaired translation and template activity in response to injury, when compared with the rats in the high dose group. These results are attributed to the lesser degree of circulatory impairment in the low T-2 toxin dosage group, which allows a higher amount of T-2 toxin to interact with the cells.