Antibodies, implantation and embryo survival

Regardless of genotype, offspring of VIP-deficient female mice exhibit developmental delays and deficits in social behavior

Pharmacological studies indicate that vasoactive intestinal peptide (VIP) may be necessary for normal embryonic development in the mouse. For example, VIP antagonist treatment before embryonic day 11 resulted in developmental delays, growth restriction, modified adult brain chemistry and reduced social behavior. Here, developmental milestones, growth, and social behaviors of neonates of VIP-deficient mothers (VIP +/-) mated to VIP +/- males were compared with the offspring of wild type mothers (VIP +/+) mated to VIP +/+ and +/- males, to assess the contributions of both maternal and offspring VIP genotype. Regardless of their own genotype, all offsprings of VIP-deficient mothers exhibited developmental delays. No delays were seen in the offspring of wild type mothers, regardless of their own genotype. Body weights were significantly reduced in offspring of VIP-deficient mothers, with VIP null (-/-) the most affected. Regardless of genotype, all offspring of VIP-deficient mothers expressed reduced maternal affiliation compared with wild type offspring of wild type mothers; +/- offspring of wild type mothers did not differ in maternal affiliation from their wild type littermates. Play behavior was significantly reduced in all offsprings of VIP-deficient mothers. Maternal behavior did not differ between wild type and VIP-deficient mothers, and cross-fostering of litters did not change offspring development, indicating that offspring deficits were induced prenatally. This study illustrated that the VIP status of a pregnant mouse had a greater influence on the growth, development and behavior of her offspring than the VIP genotype of the offspring themselves. Deficiencies were apparent in +/+, +/- and -/- offspring born to VIP-deficient mothers; no deficiencies were apparent in +/- offspring born to normal mothers. These results underscore the significant contribution of the uterine environment to normal development and indicate a potential usefulness of the VIP knockout mouse in furthering the understanding of neurodevelopmental disorders with social behavior deficits such as autism.

Target-oriented anti-implantation approaches for pregnancy interception: Experiences in the rhesus monkey model

Blastocyst implantation is a critical process in the establishment of pregnancy in eutherian mammals and requires a harmonious symbiosis between the developing conceptus and the differentiating maternal uterus. A better understanding of this symbiotic relationship will provide novel approaches and interventions for realizing anti-implantation strategies for effective fertility regulation and reproductive health care management. We have been using the rhesus monkey (Macaca mulatta) as a nonhuman primate model to this end. In the present study, the process of progesterone-mediated regulation of endometrial receptivity for blastocyst implantation has been targeted by the use of mifepristone as an emergency contraceptive agent. Furthermore, based on cell-specific, temporal and spatial distribution of vasotropic cytokines and mediators in the "receptive" and periimplantation periods, the pregnancy interceptive potentials of (a) monoclonal antibody (MAb) to leukemia inhibitory factor (LIF); (b) inhibitors of nitric oxide synthase [e.g., N6-nitro-l-arginine (l-NAME) and aminoguanidine]; and (c) MAb to vascular endothelial growth factor (VEGF) were examined. LIF is a progesterone-responsive pleiotropic cytokine that functions as a proinflammatory cytokine, together with interleukins 1 and 6, during the process of implantation-placentation in primates, and its immunoneutralization with MAb resulted in inhibition (p<.04) of pregnancy establishment in the rhesus monkey. However, timed administration of l-NAME or aminoguanidine failed to inhibit blastocyst implantation in a significant manner. Also, no synergistic antinidatory action of antiprogestin combined with l-NAME was detected in the rhesus monkey. The application of MAb to VEGF during the periimplantation period, on the other hand, led to significant (p<.04) prevention of pregnancy without influencing steroid hormone levels in the circulation. Our data lend support to the hypothesis that VEGF is essential for pregnancy establishment and that trophoblast-derived VEGF, acting via its specific receptors Flt-1 and KDR, is necessary for blastocyst implantation. The use of cDNA-based expression arrays followed by differential display analysis has provided preliminary understanding of the nature of gene cluster networks operative in the receptive endometrium of potential conception cycles in the rhesus monkey. This knowledge may, in the future, lead to further innovative anti-implantation strategies for targeted pregnancy interception.

Effect of undernutrition on the distribution of progesterone in the uterus of ewes during the luteal phase of the estrous cycle

The effect of undernutrition on ovarian and uterine venous progesterone concentrations and endometrial progesterone content on Days 5 and 10 of the estrous cycle were studied. Forty ewes were synchronized using progestagen pessaries. At pessary withdrawal, the ewes were fed diets to provide either 1.5 or 0.5 times the daily maintenance requirement (Group H, n = 20 and Group L, n = 20, respectively). Ewes fed the low nutrition diet (Group L) had higher mean peripheral progesterone concentrations than those fed the high plane diet (Group H; P < 0.05) but lower endometrial progesterone content on Day 5 (P < 0.05). Neither ovarian nor uterine venous levels were affected by nutrition on either Day 5 or 10. Progesterone concentrations in blood samples collected ipsilateral to ovaries bearing a corpus luteum (CL) were higher than in the contralateral samples (P < 0.001). It is concluded that undernutrition can produce a reduction of endometrial content of progesterone the first week after mating. Since no differences in ovarian venous concentrations were observed, it remains to be shown whether this variation is due to other variables, such as the population of endometrial progesterone receptors or other nonhormonal factors.

Neutralization of pregnancy-preventing activity of cabergoline, a dopamine agonist with progesterone

Cabergoline (Cab), a dopamine agonist, inhibits the production and/or release of prolactin and reduces progesterone biosynthesis. Cab at doses of 20 microg/kg/d and higher administered on Days 1, 2 and 3 of pregnancy prevented implantation of fertilized ova in all treated female rats. The pregnancy-preventing activity of Cab is attributed to a deficiency of progesterone since estradiol levels remain unchanged. To validate the hypothesis that progesterone deficiency is the cause of the infertility, exogenous progesterone was administered to Cab-treated pregnant female rats and their fertility assessed. Progesterone at a dose of 5 mg/kg/d sc was administered on Days 1 to 7 of pregnancy to female rats treated with Cab (20 and 60 microg/kg/d) on Days 1, 2 and 3 of pregnancy. All progesterone-treated animals became pregnant, and all mated female rats treated with Cab (60 microg/kg/d) and progesterone (5 mg/kg/d) on Days 1 to 7 inclusive became pregnant. In conclusion, progesterone can neutralize the pregnancy preventing activity of Cab. Pregnant female rats treated with Cab can be used to assay for progestagenic activity of compounds.

Transfer of heterologous immunoglobulin into the uterine lumen of pigs

Transfer of circulating heterologous immunoglobulin G (IgG) into the uterine lumen of pigs has not been reported. The present study determined if ovine IgG (oIgG) could be transferred into the uterine lumen of pigs. Six gilts (nonparous female pigs) were injected i.v. with either immune sheep serum (25 or 50 ml) to porcine uteroferrin (Uf) or non-immune sheep serum (50 ml) on days 9, 11 and 13 of the estrous cycle. Serum was collected daily from days 9 to 15 and uterine flushings were collected at hysterectomy on day 15. An ELISA detecting oIgG was used to determine levels of oIgG in pig sera and uterine flushings. High oIgG levels in serum (ranging from 87 +/- 11 to 141 +/- 14 micrograms/ml) were maintained by injecting the gilts at 48 h intervals with ovine antiserum to porcine Uf. Serum concentrations of oIgG did not differ (P > 0.05) regardless of whether immune or non-immune sera or different doses of immune serum were injected. oIgG in uterine flushings (2 +/- 1 micrograms/uterine flushing) was detectable when the samples were concentrated 40-fold, but were lower (P < 0.01) than serum levels of oIgG (107 +/- 10 micrograms/ml). Results indicate that small amounts of circulating heterologous IgG can be transferred into the uterine lumen of pigs. However, passive immunization may not result in titers high enough to examine in vivo functions of proteins secreted into the uterine lumen of pigs.