Resistin expression and plasma concentration peak at different times during pregnancy in rats

Abstract

Resistin has been proposed as both an anti-adipogenic factor and an inducer of insulin resistance. During late pregnancy, white adipose tissue mass increases and insulin sensitivity decreases. To check for the involvement of resistin in these processes, we measured plasma resistin in pregnant and non-pregnant rats and in lactating dams. Plasma resistin increased by day 15 of pregnancy and remained high 5 days post partum. The simultaneous increase in plasma resistin concentration and the decrease in insulin sensitivity is compatible with resistin depressing maternal insulin sensitivity. Resistin expression increased 5-15 times in visceral white adipose tissue depots by day 8 of pregnancy but was similar to pre-pregnancy values by day 19. Resistin expression in the placenta and mammary gland was similar to that in the parametrial adipose depot by day 8 but was almost null by day 19. There was therefore a time-lag between the peaks in expression and in plasma concentration. White adipose tissue mass increased without changes in adipocyte size once peaks in resistin expression had passed, which is compatible with an anti-adipogenic role for enhanced resistin expression. A bolus injection of chorionic gonadotrophin -which peaks in early pregnancy -to non-pregnant rats increased resistin expression in white adipose tissue, indicating that this hormone is involved in controlling resistin expression. Resistin was not detected in cerebrospinal fluid. Our results have suggested a role for resistin in pregnancy.

Fasting-induced adipose factor identified as a key adipokine that is up-regulated in white adipose tissue during pregnancy and lactation in the rat

“…These observations suggest that there are species differences in the response of adiponectin to pregnancy. There have been two papers, in addition to the present study, reporting resistin mRNA expression in WAT during pregnancy (Nogueiras et al 2003, Caja et al 2005a. They reported elevated resistin mRNA in WAT in early pregnancy and a decrease in late pregnancy.…”

Pregnancy and the endocrine regulation of the baroreceptor reflex

“…Moreover, placental lactogen has been identified as one factor that reduces brain leptin sensitivity in the context of energy balance (4). Placental lactogen (40,114) and other circulating factors emanating from the placenta and adipose tissue, such as progesterone, TNF-␣, IL-6, resistin, and free fatty acids (9,10,32,33,57,66,75,106), decrease insulin sensitivity during pregnancy. Therefore, these factors may also contribute to baroreflex impairment by decreasing brain levels or actions of insulin in brain to support baroreflex gain.…”

Adipocytokines in Particular Pregnancy Disorders

“…Furthermore, resistin is expressed in the human placenta and has been postulated to play a role in regulating energy metabolism in pregnancy [88,89]. Recent reports [90], have also demonstrated markedly high levels of resistin in umbilical plasma samples, affecting adipose tissue in utero. Nevertheless, most studies failed to show a correlation between plasma resistin levels and insulin sensitivity in humans [91].…”