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Stress or glucocorticoid (GC) treatment in perinatal life can induce long-term changes in the sensitivity of the hypothalamo-pituitary-adrenocortical axis to the feedback actions of GCs and, hence, in GC secretion. These changes have been ascribed largely to changes in the sensitivity of the limbic system, and possibly the hypothalamus, to GCs. Surprisingly, the possibility that early life stress/GC treatment may also exert irreversible effects at the pituitary level has scarcely been addressed. Accordingly, we have examined the effects of pre- and neonatal dexamethasone treatment on the adult male pituitary gland, focusing on the following: 1) the integrity of the acute annexin 1 (ANXA1)-dependent inhibitory actions of GCs on ACTH secretion, a process requiring ANXA1 release from folliculostellate (FS) cells; and 2) the morphology of FS cells and corticotrophs. Dexamethasone was given to pregnant (d 16-19) or lactating (d 1-7 postpartum) rats via the drinking water (1 microg/ml); controls received normal drinking water. Pituitary tissue from the offspring was examined ex vivo at d 90. Both treatment regimens reduced ANXA1 expression, as assessed by Western blotting and quantitative immunogold labeling. In particular, the amount of ANXA1 located on the outer surface of the FS cells was reduced. By contrast, IL-6 expression was increased, particularly by the prenatal treatment. Pituitary tissue from untreated control rats responded to dexamethasone with an increase in cell surface ANXA1 and a reduction in forskolin-induced ACTH release. In contrast, pituitary tissue from rats treated prenatally or neonatally with dexamethasone was unresponsive to the steroid, although, like control tissue, it responded readily to ANXA1, which readily inhibited forskolin-driven ACTH release. Prenatal dexamethasone treatment reduced the size but not the number of FS cells. It also caused a marked reduction in corticotroph number and impaired granule margination without affecting other aspects of corticotroph morphology. Similar but less marked effects on pituitary cell morphology and number were evident in tissue from neonatally treated rats. Our study shows that, when administered by a noninvasive process, perinatal GC treatment exerts profound effects on the adult pituitary gland, impairing the ANXA1-dependent GC regulation of ACTH release and altering the cell profile and morphology.

Annexin 1 (ANXA1) was originally identified as a mediator of the anti-inflammatory actions of glucocorticoids (GCs) in the host defense system. Subsequent work confirmed and extended these findings and also showed that the protein fulfills a wider brief and serves as a signaling intermediate in a number of systems. ANXA1 thus contributes to the regulation of processes as diverse as cell migration, cell growth and differentiation, apoptosis, vesicle fusion, lipid metabolism, and cytokine expression. Here we consider the role of ANXA1 in the neuroendocrine system, particularly the hypothalamo-pituitary-adrenocortical (HPA) axis. Evidence is presented that ANXA1 plays a critical role in effecting the negative feedback effects of GCs on the release of corticotrophin (ACTH) and its hypothalamic-releasing hormones and that it is particularly pertinent to the early-onset actions of the steroids that are mediated via a nongenomic mechanism. The paracrine/juxtacrine mode of ANXA1 action is discussed in detail, with particular reference to the significance of the secondary processing of ANXA1, the processes that control the intracellular and transmembrane trafficking of the protein of the molecule and the mechanism of ANXA1 action on its target cells. In addition, the role of ANXA1 in the perinatal programming of the HPA axis is discussed.

The N-formyl peptide receptors (FPRs) are a family of G-protein coupled receptors that respond to proinflammatory N-formylated bacterial peptides (e.g., formyl-Met-Leu-Phe, fMLF) and, thus, contribute to the host response to bacterial infection. Paradoxically, a growing body of evidence suggests that some members of this receptor family may also be targets for certain anti-inflammatory molecules, including annexin A1 (ANXA1), which is an important mediator of glucocorticoid (GC) action. To explore further the potential role of FPRs in mediating ANXA1 actions, we have focused on the pituitary gland, where ANXA1 has a well-defined role as a cell-cell mediator of the inhibitory effects of GCs on the secretion of corticotrophin (ACTH), and used molecular, genetic, and pharmacological approaches to address the question in well-established rodent models. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis identified mRNAs for four FPR family members in the mouse anterior pituitary gland, . Functional studies confirmed that, like dexamethasone, ANXA1 and two ANXA1-derived peptides (ANXA1 1-188 and ANXA1 ) inhibit the evoked release of ACTH from rodent anterior pituitary tissue in vitro. Fpr1 gene deletion failed to modify the pituitary responses to dexamethasone or ANXA1 . However, lipoxin A4 (LXA4, 0.02-2μM, a lipid mediator with high affinity for Fprrs1) mimicked the inhibitory effects of ANXA1 on ACTH release as also did fMLF in high (1-100 μM) but not lower (10-100 nM) concentrations. Additionally, a nonselective FPR antagonist (Boc1, 100 μM) overcame the effects of dexamethasone, ANXA1 1-188 , ANXA1 , fMLF, and LXA4 on ACTH release, although at a lower concentration (50 μM), it was without effect. Together, the results suggest that the actions of ANXA1 in the pituitary gland are independent of Fpr1 but may involve other FPR family members, in particular, Fpr-rs1 or a closely related receptor. They thus provide the first evidence for a role of the FPR family in the regulation of neuroendocrine function.-John, C. D., Sahni, V., Mehet, D., Morris, J. F., Christian, H. C., Perretti, M., Flower, R. J., Solito E., Buckingham J. C. Formyl peptide receptors and the regulation of ACTH secretion: targets for annexin A1, lipoxins, and bacterial peptides. UKPMC Funders Group Author Manuscript UKPMC Funders Group Author ManuscriptTHE HYPOTHALAMO-PITUITARY-ADRENOCORTICAL (HPA) axis plays an essential role in the maintenance of homeostasis. In normal circumstances its activity is tightly regulated with obvious changes in glucocorticoid (GC) secretion occurring only in accord with the circadian rhythm and in conditions of stress. However, subtle disturbances in GC secretion and/or activity are not uncommon in clinical medicine and are increasingly linked to the pathogenesis of diseases, which are endemic in the Western world, e.g., obesity, hypertension, and depression. Such disturbances can be brought about by a variety of mechanisms, including impairments of the negative feedback regulation of the axis...

Annexin 1 (ANXA1) is an important mediator of glucocorticoid action in the neuroendocrine system. As the activity of this protein in other systems is modulated by phosphorylation of its N-terminal domain, we have explored the significance of this domain and its phosphorylation status to ANXA1 actions within the pituitary gland, using an established in vitro preparation. Two N-terminal peptides, ANXA1(Ac2-26) and ANXA1(Ac1-50), inhibited forskolin-evoked ACTH and prolactin release; however, they lacked the potency and full efficacy of the parent molecule (ANXA1(1-346)), whereas other shorter N-terminal sequences were without effect. A chimeric protein comprising ANXA1(1-44) and the C-terminal core of ANXA5 (ANXA5(20-320)) also produced a partial inhibition of peptide release. Protein kinase C (PKC) blockade (PKC(19-36)) abolished the inhibitory effects of dexamethasone on forskolin-evoked peptide release and attenuated the antisecretory actions of ANXA1(Ac2-26.) ANXA5, which sequesters PKC in other systems, produced similar effects. PKC(19-36) also blocked the dexamethasone- induced translocation of a serine phosphorylated species of ANXA1 from the cytoplasm to the outer cell surface. These results suggest that 1) the N-terminal domain plays a fundamental role in effecting the inhibitory actions of ANXA1 on pituitary peptide release; 2) PKC-dependent mechanisms are essential for both the cellular exportation and the biological activity of ANXA1; and 3) ANXA1 exported from the cells is serine phosphorylated.

Annexin 1 (ANXA1) is an important mediator of glucocorticoid action in the neuroendocrine system. As the activity of this protein in other systems is modulated by phosphorylation of its N-terminal domain, we have explored the significance of this domain and its phosphorylation status to ANXA1 actions within the pituitary gland, using an established in vitro preparation. Two N-terminal peptides, ANXA1(Ac2-26) and ANXA1(Ac1-50), inhibited forskolin-evoked ACTH and prolactin release; however, they lacked the potency and full efficacy of the parent molecule (ANXA1(1-346)), whereas other shorter N-terminal sequences were without effect. A chimeric protein comprising ANXA1(1-44) and the C-terminal core of ANXA5 (ANXA5(20-320)) also produced a partial inhibition of peptide release. Protein kinase C (PKC) blockade (PKC(19-36)) abolished the inhibitory effects of dexamethasone on forskolin-evoked peptide release and attenuated the antisecretory actions of ANXA1(Ac2-26.) ANXA5, which sequesters PKC in other systems, produced similar effects. PKC(19-36) also blocked the dexamethasone- induced translocation of a serine phosphorylated species of ANXA1 from the cytoplasm to the outer cell surface. These results suggest that 1) the N-terminal domain plays a fundamental role in effecting the inhibitory actions of ANXA1 on pituitary peptide release; 2) PKC-dependent mechanisms are essential for both the cellular exportation and the biological activity of ANXA1; and 3) ANXA1 exported from the cells is serine phosphorylated.