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Raloxifene (RAL) is a selective estrogen receptor modulator presenting tissue-specific agonist activity. The aim of this study was to examine whether RAL has an estrogenic effect on carrageenan-induced acute inflammation. Adult female rats were ovariectomized (OVX) 7 wk before edema or pleurisy to deplete circulating estrogens. Edema formation and selected inflammatory markers in inflamed paw tissue were measured in intact (sham-operated) and OVX rats. Groups of OVX rats were treated with RAL (1, 3, or 10 mg/kg) or 17beta-estradiol (E2, 25 microg/kg), and these treatments began 2 d after surgery and continued until carrageenan paw edema or pleurisy. Ovariectomy amplifies the inflammation, and we found that RAL, as well as E2, attenuates inflammation and tissue damage associated with paw edema and pleurisy. In treated rats, there is a decrease in edema development and formation, and in polymorphonuclear cell infiltration and migration, as shown by myeloperoxidase measurement and cell counting. RAL and E2 treatments decrease cyclooxygenase-2 and inducible nitric oxide synthase expression in inflamed areas and counteract the inhibition of peroxisome proliferators-activated receptor-gamma expression caused by ovariectomy, restoring this receptor protein expression to sham-operated levels and identifying a possible peroxisome proliferators-activated receptor-dependent antiinflammatory effect of these drugs. Moreover, RAL and E2 increase cytoprotective heat shock protein 72 expression, which seems to be closely associated with the remission of the inflammatory reaction. In addition, we confirm the antiinflammatory effect of RAL in male rats, using a single administration of RAL or E2.

During food deprivation, plasma T(4) and T(3) levels are decreased. Under this metabolic condition, hypothalamic deiodinase type 2 (D2) activity and mRNA levels are elevated, whereas TRH mRNA levels are suppressed. Systemic T(4) administration does not reverse these hypothalamic changes. The mechanism(s) that underlies this paradoxical regulation of D2 during fasting is unknown. We hypothesize that leptin and/or glucocorticoids play a role in these mechanisms, and their interactions may be an important regulator of the hypothalamic-pituitary-thyroid axis. Thus, we assessed the effects of these hormones on D2 activity levels of food-deprived as well as fed animals using enzyme activity measurements. In food-deprived animals, corticosterone replacement reversed the inhibitory effect of adrenalectomy (ADX) on D2 induction, whereas ADX and ADX plus corticosterone replacement did not significantly affect D2 activity levels in rats fed ad libitum. Leptin administration to fed animals did not change D2 activity, whereas in fasted rats, leptin decreased D2 activity by reducing corticosterone plasma levels. When leptin was administered to fasted animals that were either ADX or ADX plus corticosterone treated at a high dose, D2 activity did not increase. Our results show that during fasting, diminishing leptin levels play a permissive role to enable glucocorticoid-induced up-regulation of D2. Thus, our observations suggest that appropriate induction of D2 activity during negative energy balance is dependent upon both leptin and glucocorticoid signaling.

In the present study we have evaluated the absolute number of the two forms of prolactin (PRL) receptor mRNA in rat peripheral blood lymphocytes and the modulation of receptor mRNA induced by changes in serum levels of endogenous PRL or by administration of ovine PRL. Lymphocytes expressed low levels of both forms of PRL receptor transcripts. Repeated treatments with ovine PRL significantly reduced levels of mRNA encoding the long form PRL receptor, whereas expression was markedly increased by repeated doses of bromocriptine. In contrast, the mRNA level of short form PRL receptor was unchanged by both treatments. The expression of long form transcripts was also markedly decreased in lymphocytes from pituitary-grafted rats. Therefore it appears that in rat peripheral lymphocytes PRL has a negative effect on the expression of its own receptor.