Ultrastructural localization of enkephalin-like immunoreactivity in the rat adrenal medulla

The PAP method was applied to adrenomedullary cells to demonstrate the subcellular localization of ELI. The labeled cell-groups were identified from flat-embedded virbratome sections by light microscopy. Electron microscopy showed that the precipitate was associated with the storage granules of the cells. The number of labeled granules varied greatly from cell to cell. In cells corresponding to those showing heavy staining by light microscopy, all the granules were stained with precipitate. It is suggested that the peptide responsible for the ELI might be released together with the catecholamines.     

Immunohistochemical localization of endothelin-1 in non-neoplastic and neoplastic adrenal gland tissue

Endothelin (ET)-1 is a 21-amino acid peptide with potent vasopressor and vasocontrictive properties. Biochemical studies suggest that this peptide occurs in adrenal glands, where it influences steroid hormone production. However, we have found no report of the topographical distribution of this peptide. The localization of ET-1 immunoreactivity in non-neoplastic (37 cases) and neoplastic adrenal glands (48 cases) was investigated with a sensitive immunohistochemical technique applied to routinely processed tissue specimens. ET-1 immunoreactivity was regularly seen in the cortex, especially in the zona fasciculata and to a varying extent also in the other two zones, but not in the medulla. The immunoreactive material appeared in the cytoplasm mostly in the form of vacuolar structures but also as grains. Focally, the cell membrane also showed immunoreactive staining. In the zona reticularis the immunoreactivity appeared mainly as cytoplasmic grains. Most cortical adenomas displayed numerous immunoreactive cells. The immunoreactivity in the tumour tissue appeared in the same forms as in normal cortex, but the reactive products were generally fewer in number. No obvious differences in immunostaining were seen between the aldosterone- and cortisol-producing adenomas or the non-functioning ones. Three of the ten carcinomas contained immunoreactive cells, but they were few, appearing focally and the ET-1 immunoreactive structures were seen as dust-like material. The difference in immunoreactivity between the benign and the malignant cortical neoplasms may be of diagnostic value. Functionally our results support a relationship between ET-1 and steroid regulation in non-neoplastic cortical tissue.     

Immunohistochemical and neurochemical evidence for the presence of serotonin in the adrenal medulla of the rat

Immunohistochemical and biochemical techniques were used to look for serotonin in the adrenal medulla of the rat. Using antibodies to serotonin, noradrenaline and adrenaline, it could be shown that the adrenaline-storing cells are highly immunoreactive for serotonin. Noradrenaline-storing cells were not stained even after administration of the precursors l-tryptophan and 5-hydroxytryptophan, or of serotonin itself. Specificity of the immune reaction was studied by both absorption and inhibition experiments. Chemical assays showed that rat adrenals contain significant amounts of serotonin (1.4 ± 0.11 μg/g wet weight) which is about 0.4% of the adrenaline levels. Serotonin could be reduced to about 10% of control by a high dose of reserpine. From differential and sucrose gradient centrifugation experiments it was concluded that serotonin is probably stored in granules also containing adrenaline. Administration of 5-hydroxytryptophan led to a marked increase of the serotonin level, preferentially in the granular fraction. This increase could be blocked almost completely by a decar☐ylase inhibitor. Serotonin administration did not result in a statistically significant increase of the serotonin concentration. Serotonin levels were not changed either after administration of l-tryptophan or the tryptophan hydroxylase inhibitor H22/54. These results indicate that there is no significant synthesis of serotonin from l-tryptophan.

It is suggested that the serotonin present in the adrenaline-storing cells is derived from circulating serotonin and/or 5-hydroxytryptophan. Serotonin taken up directly from the circulation or formed by decar☐ylation from 5-hydroxytryptophan is subsequently incorporated in the chromaffan granules.     

The rat adrenal medulla

Adult adrenal medullary cells, in many strains of rats, develop diffuse and nodular hyperplasia and neoplasia under a variety of conditions. Both endogenous and exogenous factors affect the development of these proliferative changes. The former include the animals' strain, age, and sex. The latter include drugs and other environmental agents, diet, and perhaps stress. Adrenal medullary neoplasms which arise under diverse circumstances often closely resemble each other both morphologically and functionally, and exhibit characteristics of immature chromaffin cells. Recent data indicate that normal, mature-appearing epinephrine- and norepinephrine-type chromaffin cells are able to divide, and suggest that signals which regulate chromaffin cell function also regulate cell proliferation. Prolongation of these signals or superimposed abnormalities might initiate pathological proliferative states. It remains to be determined whether the mechanisms which promote or prevent cell proliferation in the adult adrenal are related to those involved in normal development.     

Diseases of the adrenal medulla

The adrenal glands are vital in the organism's response to environmental stress. The outer cortex releases steroid hormones: glucocorticoids, mineralocorticoids and sex hormones, which are crucial to metabolism, inflammatory reactions and fluid homeostasis. The medulla is different developmentally, functionally and structurally. It co-releases catecholamines (primarily adrenaline and to some extent noradrenaline) as well as peptides by the all-or-none process of exocytosis from chromaffin granules, to aid in blood pressure and blood flow regulation, with regulated increments during the activation of the sympathetic nervous system. The co-released peptides function to regulate catecholamine release, blood vessel contraction and innate immune responses. Pathology within the adrenal medulla and the autonomic nervous system is primarily because of neoplasms. The most common tumour, called phaeochromocytoma when located in the adrenal medulla, originates from chromaffin cells and excretes catecholamines, but may be referred to as secreting paragangliomas when found in extra-adrenal chromaffin cells. Neoplasms, such as neuroblastomas and ganglioneuromas, may also be of neuronal lineage. We will also briefly discuss the catecholamine deficiency state.     

Immunohistochemical localization of antioxidant enzymes in adult Syrian hamster tissues and during kidney development.

Tissues from adult Syrian hamsters were studied with immunoperoxidase techniques using polyclonal antibodies to three antioxidant enzymes (copper, zinc and manganese forms of superoxide dismutase, and catalase). Tissues from labile organs, in which cell renewal is prominent (uterus, intestine, and transitional epithelium of the urinary tract), showed strong antioxidant enzyme immunostaining in differentiated cells but not in stem cells. In stable organs, in which cell renewal occurs at a high rate only in response to injury (kidney and adrenal), each cell type showed a specific pattern of antioxidant enzyme immunostaining. In permanent organs (brain and heart), antioxidant enzymes were regionally specific markers. Axons of the cerebellum showed more intense antioxidant enzyme staining than those of the cerebral cortex; in the heart, atria stained more intensely than ventricles. Germ cells of the testis resembled cell renewal systems in their antioxidant enzyme-immunostaining pattern: spermatogonia were negative, whereas spermatozoa were strongly positive. The tubules of the kidney showed no antioxidant enzyme immunostaining until after birth. Our results suggest that there is a prominent role for antioxidant enzymes in cell differentiation during development and cell renewal.     

Neurotensin in the human fallopian tube: Immunohistochemical localization and effects of synthetic neurotensin on motor activity in vitro

With the use of different region-specific antisera and the peroxidase-antiperoxidase (PAP) technique, neurotensin-immunoreactivity was found in nerve fibers of the human fallopian tube. Neurotensin-immunoreactive fibers occurred at blood vessels and in contact with smooth muscle cells of the muscular stratum. In vitro experiments with helical strips of the myometrium revealed dose-dependent excitatory actions of neurotensin on resting tension as well as on amplitude and frequency of spontaneous contractions. The results may suggest a neurotransmitter function of neurotensin in the regulation of human oviductal smooth muscle activity. Thus, neurotensin may be essential in the transport of the eggs through the fallopian tube.     

Two-dimensional immunoblotting analysis and immunocytochemical localization of the secretory polypeptide 7B2 in adrenal medulla

The soluble proteins of bovine chromaffin granules were subjected to 2D-electrophoresis followed by immunoblotting with an antiserum against the pituitary peptide 7B2. One immunoreactive spot was visualized at a position corresponding to a molecular weight of 24,000 and to a pI of 5.2. Using peroxidase-antiperoxidase (PAP) pre-embedding immunocytochemical technique for electron microscopy, 7B2 has been localized within secretory granules with diameters of approximately 115 and 190 nm in noradrenergic and adrenergic cells respectively. These data establish that in chromaffin granules 7B2 represents a minor component of the acidic proteins which include the chromogranins A and B, secretogranin II and the enkephalin-containing peptides.     

Oncocytoma of the adrenal gland medulla

We report an unprecedented case of an oncocytoma of the adrenal gland medulla in a 61-year-old woman. The patient presented with right flank pain and hematuria. Computed tomographic studies revealed a right adrenal gland mass that measured 2 cm, which was subsequently excised laparoscopically. Grossly, the tumor in the medulla measured 1.9 × 1.2 cm, weighed 5 g, and had a solid tan-brown cut surface. Histologically, it consisted of large tumor cells containing eosinophilic granular cytoplasm arranged in trabecular and nodular patterns. Electron microscopy revealed closely packed mitochondria in the cytoplasm of almost all tumor cells. The tumor cells were immunohistochemically positive for vimentin. The patient resumed usual activities 2 weeks after surgery, and at 6-month follow-up, she is doing well.     

Ganglioneuroma of the adrenal medulla]

Ganglioneuroma of the left adrenal medulla is found in a 46 year old patient dying from the arterial hypertension. A crucial role of the tumour in the genesis of hypertension is suggested. According to the literature the development of ganglioneuroma occurs most frequently in utero or during first years of life. This tumour may influence the adrenal function and result in the imbalance of the host hormonal status.