Interaction between chromaffin and sustentacular cells in adrenal medulla of viscacha (Lagostomus maximus maximus)

Histological and Ultrastructural Studies of the Unique Hemopoietic-Endocrine Organ of the Grass Carp, Ctenopharyngodon idella (Valenciennes, 1844)

Specific features of the immunohistochemical and ultrastructural organization of the hemopoietic head-kidney (HK) in adult Ctenopharyngodon idella (Valenciennes, 1844) were investigated using light and transmission electron microscopy. The HK of grass carp possessed all developmental stages of leucocytes and erythrocytes, as well as dendritic cells and epithelial reticular cells. The rodlet cells were expressed α-smooth muscle actin (SMA). In addition, macrophages were the most numerous cells in the HK, which aggregated into structures called melanomacrophage centers (MMCs). On contrary, the chromaffin and interrenal cells (ICs) were mixed and organized into large anastomosing cords, which lined the posterior cardinal veins of the HK, and associated with many blood capillaries. The ICs displayed the characteristic features of steroid-producing cells. Three types of chromaffin cells: adrenaline, noradrenaline, and small granule-containing cells were observed in the HK. Glial fibrillary acidic protein (GFAP)-positive sustentacular cells were marked among the chromaffin cells. Hemopoietic cells, immune cells, MMCs, rodlet cells, in addition to three types of chromaffin cells and one type of interrenal cells in the HK were correlated with the functional significance of the fish concerned.

WITHDRAWN: Structural, ultrastructural, and immunohistochemical characteristics of the cell composition of the head kidney of grass carp (Ctenopharyngodon idella)

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Melatonin activates the vascular elements, telocytes, and neuroimmune communication in the adrenal gland of Soay rams during the non-breeding season

The adrenal glands of 15 adult Soay rams were used to study the effect of melatonin on their vascular elements and cellular organization. A significant increase in the cross-sectional area of the blood sinusoids was demonstrated after melatonin administration. The vimentin-expressing mesenchymal cells were increased in the melatonin-treated group. Intensive S-100 protein expression was observed in the sustentacular cells and telocytes (TCs) of the treated groups. Moreover, S-100 protein expressed intensively in the dendritic cells that distributed around the blood sinusoids. Dendritic cells showed positive immunoreactivity for CD8 and CD103. Many dendritic cells with well-defined processes were observed close to the nerve fibers after melatonin administration. A significant increase in the number and diameter of dendritic cells after melatonin treatment was demonstrated. Many highly active TCs were observed in the medulla of the treated group, which were characterized by long telopodes (Tps) containing abundant secretory vesicles that released into the extracellular milieu and towards the dendritic cells. In the melatonin-treated groups, the nerve fibers showed a significant increase in their cross-sectional area accompanied by an increase in the activity of Schwann cells and neighboring dendritic cells. In the treated group, TCs and DCs appear to contribute to angiogenesis. A planner contact between Tps and the stem cell was demonstrated in the treated group. Melatonin induced a stimulatory action on the vascular and neuronal elements of the adrenal gland. Moreover, it enhances the activity of a variety of cells including telocytes, dendritic, sustentacular, and Schwann cells.

Immunomorphometric variations of sustentacular cells of the male viscacha adrenal medulla during the annual reproductive cycle. Effects of androgens and melatonin

The adrenal medulla is crucial for the survival of species facing significant environmental changes. The parenchyma is composed mainly of chromaffin cells, ganglion cells and sustentacular cells (SC). The male viscacha exhibits seasonal variations of gonadal activity and other metabolic functions. The aim of this work was to investigate the influence of the reproductive conditions on the morphology of SC of this rodent. In addition, the effects of testosterone and melatonin on these cells were studied. Immunoexpression of S100 protein, GFAP and vimentin were analyzed. Furthermore, the distribution of adrenergic and noradrenergic chromaffin cells subpopulations was studied for the first time in this species. SC present long cytoplasmic processes in contact with chromaffin cells, probably generating an intraglandular communication network. Significant differences (p < 0.05) in the %IA (percentage of immunopositive area) for the S100 protein were observed according to winter (4.21 ± 0.34) and summer (3.51 ± 0.15) values. In castrated animals, the %IA (6.05 ± 0.35) was significantly higher in relation to intact animals (3.95 ± 0.40). In melatonin-treated animals the %IA (3.62 ± 0.23) was significantly higher compared to control animals (2.65 ± 0.26). GFAP immunoexpression was negative and no noradrenergic chromaffin cells were detected suggesting an adrenergic phenotype predominance. Vimentin was observed in SC, endothelial cells and connective tissue. Results indicate that SC exhibit variations along the annual reproductive cycle, along with castration and the melatonin administration. Our results suggest that in this rodent SC are not only support elements, but also participate in the modulation of the activity of the adrenal medulla; probably through paracrine effects.

From proliferation to target innervation: signaling molecules that direct sympathetic nervous system development

The sympathetic division of the autonomic nervous system includes a variety of cells including neurons, endocrine cells and glial cells. A recent study (Furlan et al. 2017) has revised thinking about the developmental origin of these cells. It now appears that sympathetic neurons and chromaffin cells of the adrenal medulla do not have an immediate common ancestor in the form a "sympathoadrenal cell", as has been long believed. Instead, chromaffin cells arise from Schwann cell precursors. This review integrates the new findings with the expanding body of knowledge on the signalling pathways and transcription factors that regulate the origin of cells of the sympathetic division of the autonomic nervous system.

A Seasonal and Age-Related Study of Interstitial Cells in the Pineal Gland of Male Viscacha (Lagostomus maximus maximus)

The pineal gland of viscacha exhibits histophysiological variations throughout the year, with periods of maximal activity in winter and minimal activity in summer. The aim of this work is to analyze the interstitial cells (IC) in the pineal gland of male viscachas in relation to season and age. The S-100 protein, glio-fibrillary acidic protein (GFAP), and vimentin were detected in adult and immature animals by immunohistochemistry (IHC). Double-IHC was also performed. The S-100 protein was localized within both, IC nucleus and cytoplasm. GFAP was present only in the cytoplasm. Vimentin was expressed in some IC, besides endothelial cells, and perivascular spaces. In the adult males, the morphometric parameters analyzed for the S-100 protein and GFAP exhibited seasonal variations with higher values of immunopositive area percentage in winter and lower values in summer, whereas the immature ones showed the lowest values for all the adult animals studied. Colocalization of S-100 protein and GFAP was observed. The IC exhibited differential expression for the proteins studied, supporting the hypothesis of the neuroectodermal origin. The IC generate an intraglandular communication network, suggesting its participation in the glandular activity regulation processes. The results of double-IHC might indicate the presence of IC in different functional stages, probably related to the needs of the cellular microenvironment. The morphometric variations in the proteins analyzed between immature and adult viscachas probed to be more salient in the latter, suggesting a direct relationship between the expression of the S-100 protein and GFAP, and animal age. Anat Rec, 2017. © 2017 Wiley Periodicals Inc. Anat Rec, 300:1847-1857, 2017. © 2017 Wiley Periodicals, Inc.

Roles of connexins and pannexins in (neuro)endocrine physiology

To ensure appropriate secretion in response to demand, (neuro)endocrine tissues liberate massive quantities of hormones, which act to coordinate and synchronize biological signals in distant secretory and nonsecretory cell populations. Intercellular communication plays a central role in this control. With regard to molecular identity, junctional cell-cell communication is supported by connexin-based gap junctions. In addition, connexin hemichannels, the structural precursors of gap junctions, as well as pannexin channels have recently emerged as possible modulators of the secretory process. This review focuses on the expression of connexins and pannexins in various (neuro)endocrine tissues, including the adrenal cortex and medulla, the anterior pituitary, the endocrine hypothalamus and the pineal, thyroid and parathyroid glands. Upon a physiological or pathological stimulus, junctional intercellular coupling can be acutely modulated or persistently remodeled, thus offering multiple regulatory possibilities. The functional roles of gap junction-mediated intercellular communication in endocrine physiology as well as the involvement of connexin/pannexin-related hemichannels are also discussed.

Gap junction-mediated intercellular communication in the adrenal medulla: an additional ingredient of stimulus-secretion coupling regulation

The traditional understanding of stimulus-secretion coupling in adrenal neuroendocrine chromaffin cells states that catecholamines are released upon trans-synaptic sympathetic stimulation mediated by acetylcholine released from the splanchnic nerve terminals. Although this statement remains largely true, it deserves to be tempered. In addition to its neurogenic control, catecholamine secretion also depends on a local gap junction-mediated communication between chromaffin cells. We review here the insights gained since the first description of gap junctions in the adrenal medullary tissue. Adrenal stimulus-secretion coupling now appears far more intricate than was previously envisioned and its deciphering represents a challenge for neurobiologists engaged in the study of the regulation of neuroendocrine secretion. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.

Revisiting the stimulus-secretion coupling in the adrenal medulla: role of gap junction-mediated intercellular communication

The current view of stimulation-secretion coupling in adrenal neuroendocrine chromaffin cells holds that catecholamines are released upon transsynaptic sympathetic stimulation mediated by acetylcholine released from the splanchnic nerve terminals. However, this traditional vertical scheme would merit to be revisited in the light of recent data. Although electrical discharges invading the splanchnic nerve endings are the major physiological stimulus to trigger catecholamine release in vivo, growing evidence indicates that intercellular chromaffin cell communication mediated by gap junctions represents an additional route by which biological signals (electrical activity, changes in intracellular Ca(2+) concentration,...) propagate between adjacent cells and trigger subsequent catecholamine exocytosis. Accordingly, it has been proposed that gap junctional communication efficiently helps synapses to lead chromaffin cell function and, in particular, hormone secretion. The experimental clues supporting this hypothesis are presented and discussed with regards to both interaction with the excitatory cholinergic synaptic transmission and physiopathology of the adrenal medulla.