The effect of sex steroids and hormonal contraceptives upon thymus and spleen of intact female rats

Effects of estrogen receptor subtype-selective agonists on immune functions in ovariectomized mice

“…However, no marked difference was found in thymic weight between PPT + DPN group and PPT group. A possible explanation is that the functional parenchyma of the atrophied thymus due to estrogenic compound exposure is being replaced with fat and connective tissue as suggested by the histological examination in our study and others [32]. This may make thymic weight not as sensitive as thymic cellularity in reflecting the degree of parenchyma atrophy in these thymus glands.…”

Age-Associated Remodeling of Thymopoiesis: Role for Gonadal Hormones and Catecholamines

“…In keeping with this notion are data showing that a rise in circulating levels of both ovarian and testicular gonadal steroids, which is induced by the hormone administration, in rodents causes thymic atrophy similar to that seen in aging [21][22][23][24][25][26] . Furthermore, surgical or chemical gonadectomy via administration of gonadotropin-releasing hormone (GnRH) agonists, which cause a reversible inhibition of testicular steroidogenesis [143] , before puberty postpones thymic involution, while later in life it produces reversal of aging changes in the thymi of both sexes [23,27,28,[30][31][32][33][34][143][144][145][146] .…”

“…Given that (1) the onset of age-associated thymic involution coincides with the rise in the levels of gonadal steroids at puberty [14] and (2) the rise in levels of these hormones in rodents of both sexes causes thymic atrophy similar to that observed during aging [21][22][23][24][25][26] , while in both sexes gonadectomies performed before and after puberty postpone/prevent thymic involution and produce reversal of age-associated thymus changes, respectively [23,[27][28][29][30][31][32][33][34] , the gonadal steroids have been implicated in initiation and/or progression of thymus involution. Understanding the putative role of gonadal steroids in thymic involution is impossible without deep insight into the extremely complex mechanisms of their action.…”

Role of ovarian hormones in age-associated thymic involution revisited

“…Indeed, in rodents of both sexes, elevation of gonadal hormone levels in young animals induces thymic atrophy similar to that observed in aged rats (Kuhl et al 1983;Luster et al 1984;Windmill et al 1993;Dulos and Bagchus 2001;Oner and Ozan 2002;Yellayi et al 2002), whereas surgical castration before puberty and in early adulthood prevents thymic involution and reverses the early involutive changes, respectively (Kendall et al 1990;Windmill et al 1993;Leposavić et al 1996;Windmill and Lee 1998;Pejcić-Karapetrović et al 2001;Heng et al 2005).…”