The anorectic effect of oestradiol does not involve changes in plasma and cerebrospinal fluid leptin concentrations in the rat

Abstract

Oestradiol is a potent anorectic agent that reduces both food intake and body weight. Since leptin is known to reduce food intake, we first analysed if the anorectic effect of oestradiol is driven by an increased leptin concentration in either cerebrospinal fluid or plasma. Oestradiol also reduces body weight and fat mass. Accordingly, a decrease in plasma leptin concentration can also be expected after an oestradiol-driven reduction in fat mass. To test this hypothesis was the second aim of this study. Female Wistar rats received oestradiol chronically during 14 days. During the first week of treatment there was a reduction in food intake, body weight and fat mass that returned to initial values during the second week, but no changes in ob mRNA levels were found in white adipose tissue depots. There was no effect of treatment or time on plasma and cerebrospinal fluid leptin concentrations. Therefore, the anorectic effect of oestradiol is not driven by an increase in leptin concentration either in plasma or in cerebrospinal fluid, and the reduction in fat mass that oestradiol produces is not followed by a reduction leptin concentration.

Perinatal overfeeding in rats results in increased levels of plasma leptin but unchanged cerebrospinal leptin in adulthood

“…The CSF (100-150 ml) was withdrawn under gentle suction after the introduction of a 27-G needle into the cistern magna. [21][22][23][24][25] Only CSF samples that were not contaminated with blood, as judged by the absence of an erythrocyte pellet after centrifugation, were used. Equal volumes of CSF from three or four samples from rats of the same group were pooled.…”

“…Equal volumes of CSF from three or four samples from rats of the same group were pooled. 22,24,25 Owing to the presence of circadian changes in hypothalamic mRNA content of the neuropeptides evaluated in this study, 11,[26][27][28] the rats (NL and SL) from each experiment (two independent experiments) were killed on the same day (1800-2000 hours) just before the dark phase (20:00 hours). 11 To completely avoid any possible circadian effect, animals from each group (NL or SL) were killed alternately, rather than killing all the animals from one experimental group before starting the next.…”

“…The amount of primary antibody employed was reduced to 40 ml and the other components of the kit were also reduced accordingly. [23][24][25] The standard curve obtained with the reduced volumes and new standards was validated with the quality controls and the values fit their expected range. [23][24][25] In these new conditions, the limit of sensitivity for the assay was 0.015 ng/ml [23][24][25] and the coefficients of intra-assay and of…”

Plasma Leptin Concentration in Tamoxifen-Treated Ovariectomized Rats

“…In several reports, estrogen increases leptin production in ovariectomized rats [19,20]. However, other reports show that estrogens have no effects on the plasma leptin level in rats [21][22][23][24]. On the other hand, serum leptin concentrations are not influenced by estradiol concentration in postmenopausal women [25].…”

Sex Steroid Receptor Expression Profile in Brown Adipose Tissue. Effects of Hormonal Status

“…Thus, sexual hormones have been proposed as key factors that could account, in part, for these differences by influencing feeding behaviour [8,9] and central nervous responses [10,11]. Nevertheless, direct actions of sex hormones on adipose tissue should also be considered as direct effects of sex hormones in determining fat distribution and accumulation [12].…”