Effect of bombesin on the structure and function of the rat adrenal cortex

Expression of progenitor markers is associated with the functionality of a bioartificial adrenal cortex

Encapsulation of primary bovine adrenocortical cells in alginate is an efficacious model of a bioartificial adrenal cortex. Such a bioartificial adrenal cortex can be used for the restoration of lost adrenal function in vivo as well as for in vitro modeling of the adrenal microenvironment and for investigation of cell–cell interactions in the adrenals. The aim of this work was the optimization of a bioartificial adrenal cortex, that is the generation of a highly productive, self-regenerating, long-term functioning and immune tolerant bioartificial organ. To achieve this, it is necessary that adrenocortical stem and progenitor cells are present in the bioartificial gland, as these undifferentiated cells play important roles in the function of the mature gland. Here, we verified the presence of adrenocortical progenitors in cultures of bovine adrenocortical cells, studied the dynamics of their appearance and growth and determined the optimal time point for cell encapsulation. These procedures increased the functional life span and reduced the immunogenicity of the bioartificial adrenal cortex. This model allows the use of the luteinizing hormone-releasing hormone (LHRH) agonist triptorelin, the neuropeptide bombesin, and retinoic acid to alter cell number and the release of cortisol over long periods of time.

Pulmonary Neuroendocrine Cells and Lung Development

Pulmonary neuroendocrine cells produce bioactive peptides such as gastrin-releasing peptide (GRP) at high levels in developing fetal lung. The role of GRP and other peptides in promoting branching morphogenesis, cell proliferation, and cell differentiation during lung organogenesis is reviewed. Possible roles for bioactive peptides derived from these cells in the pathophysiology of perinatal lung disorders are discussed.

Neuropeptides in the adrenal gland: distribution, localization of receptors, and effects on steroid hormone synthesis

In this review we defined and classified the neuropeptides (NPs) related to the adrenal gland, according to Palkovits (Frontiers Neuroendocrinol 10:1 1988). The concentration (RIA) and distribution (immunohistochemistry) of NPs, as well as the localization of the receptors (radioligand studies) were summarized. Direct effects of NPs on aldosterone and corticosterone synthesis obtained by in vivo, in situ perfusion, and in vitro experimental approaches were reviewed. Data (from different rat strains and genders) for 35 NPs are presented.

Investigations on the acute effects of neuropeptides on the pituitary-adrenocortical function in normal and cold-stressed rats. I. Bombesin and neuromedin B

The effects of a subcutaneous bolus injection of 2 micrograms bombesin (BM) or neuromedin B (NMB) on the function of the hypothalamo-pituitary-adrenocortical (HPA) axis were investigated in both normal and cold-stressed rats. The blood concentrations of ACTH, corticosterone (B) and aldosterone (ALDO) were measured by specific radioimmunoassays 1, 2 or 4 h after the neuropeptide administration. Cold stress strikingly enhanced plasma levels of ACTH, B and ALDO, and these rises lasted unchanged until 4 h. BM and NMB significantly elevated plasma concentrations of ACTH and B in both normal and stressed animals. In both groups of rats the level of circulating ALDO was not apparently affected by neuropeptides. In light of these findings the following conclusions can be drawn: (i) BM and NMB acutely activate the HPA axis, probably by acting via the same receptor; (ii) the mechanism underlying this effect of BM and NMB is independent of that involved in the cold stress-induced activation of the HPA axis; and (iii) the well-known acute ALDO secretagogue effect of ACTH is probably counteracted by a direct inhibitory action of BM and NMB on adrenal zona glomerulosa.