We have determined that in the second half of pregnancy, the primate myometrium exhibits two distinct types of activity with different pressure waves and electrical characteristics, different patterns related to light-dark cycles and different time relations to surgery and duration of gestation. We hypothesize that changes in estrogen physiology play a causal role in the control of these two types of myometrical activity. We will study and define the role of estrogens in both labor and delivery """"""""contractions"""""""" and low amplitude, tonic """"""""contractures"""""""". Labor is a multifactorial process with interconnected positive and negative feedback loops. We will focus on the role of estrogens. Good circumstantial evidence points to estrogens as a major factor controlling myometrial activity in primates. Much prostaglandin and oxytocin function is secondary to estrogen physiology. From analogy with sheep and from our's and others' data in monkeys, we hypothesize a major role for estrogens. We have used tethered chronic pregnant monkey preparations at Cornell with delivery of live fetuses up to 58 days after instrumentation. We will use this preparation in our studies to obtain controlled quantitative data for five specific aims, 1) identify the major bioactive estrogen in maternal blood, 2) identify the major bioactive estrogen in fetal blood, 3) study myometrial responses to endogenously generated estrogens, 4) studymyometrial responses to decreased estrogen production, 5) study changes in oxytocin sensitivity. Data will be stored on microprocessor based acquisition systems and computer analysed using both in-house designed and standard Fourrier-transform methods. Most studies on control of parturition and myometrial function have been done in sheep. The many differences in fetal and maternal endocrinology between primates and sheep dictate that a clear understanding of control of myometrial activity in humans awaits controlled experimental data in non-human primates. This information will aid the search for efficacious agents to control premature labor.

Project Start
1984-03-01
Project End
1989-02-28
Budget Start
1987-03-01
Budget End
1988-02-29
Support Year
4
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Cornell University
Department
Type
Schools of Veterinary Medicine
DUNS #
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Figueroa, J P; Massmann, G A; Honnebier, M B et al. (1990) Biphasic effect of a prostacyclin methyl ester analog on uterine contractility in the chronically catheterized pregnant rhesus monkey in late gestation. J Dev Physiol 13:51-7
Figueroa, J P; Honnebier, M B; Jenkins, S et al. (1990) Alteration of 24-hour rhythms in myometrial activity in the chronically catheterized pregnant rhesus monkey after a 6-hour shift in the light-dark cycle. Am J Obstet Gynecol 163:648-54
Hsu, H W; Figueroa, J P; Honnebier, M B et al. (1989) Power spectrum analysis of myometrial electromyogram and intrauterine pressure changes in the pregnant rhesus monkey in late gestation. Am J Obstet Gynecol 161:467-73
Honnebier, M B; Figueroa, J P; Rivier, J et al. (1989) Studies on the role of oxytocin in late pregnancy in the pregnant rhesus monkey: plasma concentrations of oxytocin in the maternal circulation throughout the 24-h day and the effect of the synthetic oxytocin antagonist [1-beta-Mpa(beta-(CH2)5)1,(Me(Tyr2, J Dev Physiol 12:225-32
Figueroa, J P; Honnebier, M B; Binienda, Z et al. (1989) Effect of a 48-hour intravenous delta 4-androstenedione infusion on the pregnant rhesus monkey in the last third of gestation: changes in maternal plasma estradiol concentrations and myometrial contractility. Am J Obstet Gynecol 161:481-6
Binienda, Z; Massmann, A; Wimsatt, J et al. (1989) Endocrine changes during 48 hours of food withdrawal in the pregnant rhesus monkey in the last third of gestation. J Clin Endocrinol Metab 68:1184-8
Honnebier, M B; Myers, T; Figueroa, J P et al. (1989) Variation in myometrial response to intravenous oxytocin administration at different times of the day in the pregnant rhesus monkey. Endocrinology 125:1498-503
Binienda, Z; Massmann, A; Mitchell, M D et al. (1989) Effect of food withdrawal on arterial blood glucose and plasma 13,14-dihydro-15-keto-prostaglandin F2 alpha concentrations and nocturnal myometrial electromyographic activity in the pregnant rhesus monkey in the last third of gestation: a model for preter Am J Obstet Gynecol 160:746-50