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ABSTRACT
LHRH and its analogues are known to exert direct effects on the ovary. Herein we have described a direct inhibitory effect of an LHRH antagonist (Nal-Lys antagonist: antide) on the basal progesterone (P4) and pregnenolone (P5) production by luteal cells obtained from the day-8 pregnant rat. Luteal cells incubated with two doses of antide (10−4 and 10−7 m) for 24 or 48 h showed suppression of P4 production. P5 production was suppressed by both doses of antide within 12 h of incubation. Neither dose of antide interfered with P5 production when the duration of incubation was extended beyond 12 h. The 20α-dihydroprogesterone yield from the luteal cells treated with these doses of antide remained unaffected. We estimated the activities of the cholesterol side-chain cleavage (P450scc) enzyme (which is a key enzyme involved in the conversion of cholesterol to P5) and 3β-hydroxysteroid dehydrogenase (3β-HSD) (which catalyses the conversion of P5 to P4) in the luteal cells treated with different doses of antide. Both doses of antide suppressed the activity of the P450scc enzyme after 12 h of incubation and the 3β-HSD content of the luteal cells after 48 h of incubation. These observations indicate that antide exerts a direct inhibitory effect at the level of the corpus luteum, that differential suppression of P5 and P4 during different periods of incubation with antide is due to a defect in either the P450scc or the 3β-HSD enzyme system, or both.
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Introduction Placental blood flow is a critical component of pregnancy outcome. Human placental blood flow comprises two separate compartments – the maternally derived uteroplacental circulation and the fetoplacental vasculature. This
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Introduction The steroid hormone progesterone is pivotal in the establishment and maintenance of pregnancy by promoting myometrial quiescence and may have protective effects against endometrial cancer ( Dai et al . 2002 , Druckmann & Druckmann
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accumulation of macrophages into adipose tissue via the MCP1/CCR2 pathway is necessary for the development of insulin resistance related to obesity ( Weisberg et al . 2006 ). Although it has been reported that hypertrophy of adipocyte results in late pregnancy
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Introduction Normal human pregnancy is characterized by mild fasting hypoglycemia, postprandial hyperglycemia, and hyperinsulinemia ( Cunningham et al . 2010 ). These responses are consistent with a pregnancy-induced state of insulin resistance
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Introduction Although reproduction is critical to species survival, the process of achieving and maintaining pregnancy is relatively inefficient. Maximal fecundity, the probability of conception during one menstrual cycle, is
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19 gene. During pregnancy, Cyp19 expression is low on day 4, increases progressively to reach maximal expression from days 15 to 19, and decreases from day 20 to reach undetectable levels on day 23 ( Akinola et al. 1997 , Hickey et al. 1988
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Rowett Institute of Nutrition and Health, Department of Animal Sciences, Biomathematics and Statistics Scotland, University of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
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fat deposition occurs in the final third of pregnancy, predominately in the perirenal region ( Gemmell & Alexander 1978 , Moragas & Toran 1983 ). At mid-gestation, perirenal adipose tissue (PAT) is characterised by the rapid multiplication of
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Introduction The placenta is a specialized organ during pregnancy, which in combination with fetal membranes and amniotic fluid supports normal growth and development of the fetus. The placenta has a hemochorial villus, whereby maternal blood
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Introduction Progesterone, as its name implies is a progestation hormone. Early in human pregnancy, progesterone is produced mainly by the persistent corpus luteum. After about 6–8 weeks of pregnancy, luteal production of
