Prenatal expression of interleukin 1β and interleukin 6 in the rat pituitary gland

Abstract

a b s t r a c tIt is known that interleukin 1b (IL-1b) and interleukin 6 (IL-6) are expressed post-natally in normal and tumoral cells in the anterior pituitary, and that they play a role in both the liberation of different hormones and in the growth, proliferation and tumor formation of the pituitary gland. However, their expression and role during embryonic and fetal development remain unknown. We have performed an immunocytochemistry study of prenatal expression and distribution of IL-1b and IL-6 in isolated embryonic rat Rathke's pouch prior to birth, more specifically between 13.5 and 19.5 days p.c. Western-blot analysis carried out on 19.5-day p.c. embryos showed positive immunolabelling for IL-1b and IL-6. These interleukins were initially expressed simultaneously in the rostral and ventral portions of Rathke's pouch in 15.5-day p.c. embryos, and this expression progressed caudodorsally in later developmental stages, extending to most of the hypophysis before birth. The number of cells expressing these interleukins increased throughout this period: 48.22% of anterior pituitary cells expressed IL-6 in 19.5-day embryos, whilst IL-1b was positive in 39.8% of the cells. Moreover, we have demonstrated that some adenohypophyseal cells co-express both interleukins. Such findings represent the first step towards an understanding of the physiological role of these interleukins in anterior pituitary development.

Leukemia Inhibitory Factor Represses GnRH Gene Expression via cFOS during Inflammation in Male Mice

“…While IL-1β and TNF-α are prototypical pro-inflammatory cytokines, IL-6 may function as either a pro- or anti-inflammatory cytokine depending on timing and stimulus. IL-6 synthesis in the hypothalamus is induced by IL-1β [103], and IL-6 may be engaged in the negative feedback to dampen inflammation [42]. Thus, results may vary due to the differences between in vivo and in vitro treatments, since initially induced cytokines may cause a cascade of other cytokines in vivo.…”

Ontogeny and the effects of in utero brain ischemia on interleukin‐1β and interleukin‐6 protein expression in ovine cerebral cortex and white matter

“…The differential expression patterns that we found in the ovine brain and observed by others in rodents (Brochu et al, 2011) may be related to different regulatory functions of the proteins and/or differences in developmental programming. Interleukins are expressed in normal embryonic cells at early stages of development (Moro et al, 2008). Microglia, which secret IL‐1β and IL‐6, have been identified in the developing rodent brain at the onset of neurogenesis and are thought to regulate cell survival and pruning during normal development (Deverman and Patterson, 2009; Munoz‐Fernandez and Fresno, 1998).…”

Regulation of Pituitary Function by Cytokines

“…IL-1 production has been shown in rat anterior pituitary [1] and in human pituitary adenomas in vitro [2], and recent evidence points to a role of this cytokine in the development of the rat fetal pituitary [3]. IL-1 receptors have been characterized in normal mouse anterior pituitary cells [4], in normal rat pituitary [5] and in the rat corticotrophic tumor cell line AtT-20 [4,6].…”

“…There is evidence that IL-6 is expressed in rat fetal pituitary between 18 and 36 weeks of gestation and that it plays a role in pituitary organogenesis [3]. Both IL-6 mRNA and protein production by anterior pituitary cells has been reported by several groups [45,46,47].…”