Phenobarbital-induced alterations of the rat adrenal cortex.

To determine the morpholic changes in adrenocortices induced by chronic phenobarbital therapy, the male rats were orally administered the drug daily for varying periods up to three months. Fine structural changes attributable to the drug included mitochrondrial pleomorphism and cavitation, loss of cholesterol ester clefts, reorganization of intracellular lipid, hypertrophy of the agranular endoplasmic reticulum and a juxtapositioning of the agranular endoplasmic reticulum, mitochondria and lipid droplets--all suggestive of an actively secreting cortex. The digitonin-glutaraldehyde reaction suggested an active translocation of free cholesterol from lipid droplets to the mitochondria and agranular endoplasmic reticulum following phenobarbital treatment. Phenobarbital appears to stimulate corticosteroidogenesis due in large part to enhanced hepatic corticoid metabolizing enzymes.

Fine structural and biochemical effects of aminoglutethimide and o,p'-DDD on rat adrenocortical carcinoma 494 and adrenals.

Rats bearing adrenocortical carcinoma 494 were injected daily for 7, 14, or 21 days with aminoglutethimide (AG) or o,p'-DDD. Reversibility of these steroidogenic inhibitors was determined by injecting other animals for either 14 or 21 days and sacrificing them 14 days later. While the drugs had little effect on body or tumor growth, plasma corticosterone levels were reduced a maximum of 88% in normal and 95% in tumor-bearing rats during AG chemotherapy. These levels were unaltered in normal rats by o,p'-DDD and reduced a maximum of 64% in tumor-bearing animals. Relative adrenal weights generally increased during chemotherapy and then returned to control levels. These changes were mainly due to alterations in the lipid and mitochondrial volume fractions. Lipid increased with both drugs while mitochondria increased with o,p'-DDD and decreased with AG. Cholesterol ester levels paralleled the lipid stereology more closely with AG than o,p'-DDD. With both drugs the most notable changes in tumor fine structure was a decrease in mitochondrial internal membranous vesicles and matrical density. Adrenal mitochondria had the irregular, elongated forms characteristic of tumor-bearing animals and were vacuolated (AG) or had internal rings (o,p'-DDD). The large lipid droplets observed during chemotherapy with both drugs were replaced by numerous small droplets in recovery periods.

Diazepam receptor: specific nuclear binding of [3H]flunitrazepam.

Autoradiographic localization of [3H]flunitrazepam in nuclei of the rat cerebral cortex was further confirmed by biochemical analysis of specific nuclear binding. Highly purified rat cerebral cortex nuclei were shown to bind [3H]flunitrazepam specifically. The Kd(app) for nuclear binding was 28 nM for the nuclei compared with a Kd(app) of 1.1 nM for binding of [3H] flunitrazepam to synaptosomal membrane fractions of the same tissue. Inhibition of the nuclear binding with inosine and hypoxanthine was greater than inhibition of the synaptic membrane fractions. These results lead to to conclude that specific binding may occur at both the synaptic membrane and the nuclear levels and that different endogenous ligands may compete at each site for binding. Furthermore, the possibility exists for translocation and alteration of the bound ligand complex from membrane site to nuclear site.

Fine structural studies of radiation-resistant human squamous cell carcinomas.

Squamous cell carcinomas of the oral cavity are relatively common lesions, and often can be controlled by radiation therapy. Recently, a series of these tumors has been encountered which did not respond positively to irradiation, necessitating subsequent extensive surgery. This report describes some fine structural changes which were observed in squamous cell carcinomas following exposure to x-irradiation. In addition to the common, keratin-forming differentiated cell, others which were observed were secretory-like, undifferentiated and phagocytic cells. Undifferentiated tumor cells occasionally became incorporated, at least temporarily, as a component of the blood vessel wall, perhaps reflecting metastatic potentiality. It is proposed that irradiation may either increase potential avenues of tumor cell differentiation or inactivate inhibitors thereof.

Changes in the adrenal cortex of the rat after chronic administration of the steroidogenic inhibitor U-8113.

In concert with studies of the effects of various pharmacologic inhibitors of corticosteroidogenesis on adrenocortical morphology, U-8113, an analog of amphenone B, was administered daily to Sprague-Dawley rats for 7, 14, 21 or 30 day. The primary morphological responses involved increases in adrenal weight, width of zona fasciculata, width of zona reticularis, intracellular lipids, mitochondrial size, mitochondrial vacuolation and crystalline-like inclusions, small coated vesicles, lysosomes, autophagic vacuoles and cholesterol ester clefts. In particular, the increases in lysosomes, coated vesicles and autophagic vacuoles containing morphologically altered mitochondria were considered reflective of mechanisms designed to maintain cellular integrity amidst functional impairment. Lipid analysis revealed marked increases in cholesterol esters and phospholipids, supportive of morphological observations. When permitted a 14 day recovery period following either 14 or 30 days of inhibitor therapy, most fine structural alterations and lipid derangements were diminished, and the cells approximated normal parameters.

Rat adrenocortical carcinoma 494: an integrated structural, stereological, and biochemical analysis.

Snell adrenocortical tumor 494 was implanted into male Sprague-Dawley rats and recovered 7, 14, 21, 28 or 35 days following initial detection by palpation (7-10 days following transplantation). Electron microscopic, stereological and biochemical analyses of the tumor were compared to adrenals of normal animals to serve as a baseline for further studies of the effects of chemotherapeutic agents on tumor cells. Tumor cells possessed oval or elongated mitochondrial profiles with tubular cristae, one or two very large (greater than 5 micrometer) lipid droplets, abundant ribosomes and coated vesicles, and sparse rough and smooth endoplasmic reticulum. Stereologic evaluation revealed that tumor lipid volume was 41% and mitochondrial volume 29% that of the normal adrenal controls. Tumor nuclei were 2.5 times larger than adrenocortical nuclei while cellular volumes were similar. On a net weight basis, tumor cholesterol was 55%, cholesterol ester 2.2%, and lipid phosphate 25% of respective mean values for normal adrenal glands. The tumor cholesterol: cholesterol ester ratio progressively decreased with time but remained 18-fold greater than the normal adrenal. Plasma corticosterone levels in tumor-bearing rats were elevated 3-fold by 14 days and initial detection. The adrenals of the tumor-bearing host exhibited marked involution, the extent of which was directly related to tumor size.

Fine structural studies of a human thyroid adenoma, with special reference to psammoma bodies.

The fine structural morphologic features of a microfollicular thyroid adenoma from a 28 year old female were examined. Although the patient had been laking exogenous thyroxine therapy for 14 months, the morphology of the adenoma was characterized by numerous small to medium sized follicles composed of metabolically active, well differentiated columnar cells with numerous colloid droplets, dilated granular endoplasmic reticulum, large numbers of coated vesicles and lysosomes, large colloid containing "lakes," microtubules, microfilaments, and prominent apical microvillous projections. Of special inetrest were small spherical psammomatous calcospherites ecountered in histiocytes and the interstitium. Also noteworthy were ropelike configurations observed in most of the follicular lumina. Structural-functional correlations and potential origins of psammoma bodies and calcospherites are discussed.