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J F Denef

Publications and source records attributed to J F Denef.

At least 19 recordsLinked to original sources
PubMed1998

Detection of Mycobacterium avium subsp. paratuberculosis in infected tissues by new species-specific immunohistological procedures.

We have previously described the cloning and sequencing of a gene portion coding for the terminal part of a 34-kDa protein of Mycobacterium avium subsp. paratuberculosis, the etiological agent of Johne's disease (P. Gilot, M. De Kesel, L. Machtelinckx, M. Coene, and C. Cocito, J. Bacteriol. 175:4930-4935, 1993). The recombinant polypeptide (a362) carries species-specific B-cell epitopes which do not cross-react with other mycobacterial pathogens (M. De Kesel, P. Gilot, M.-C. Misonne, M. Coene, and C. Cocito, J. Clin. Microbiol. 31:947-954, 1993). The present work describes the preparation of polyclonal and monoclonal antibodies directed against a362 and the use of these immunoglobulins for histopathological diagnosis of Johne's disease. The new immunohistological procedures herewith detailed proved to be able to identify M. avium subsp. paratuberculosis antigens in the intestinal tissues and lymph nodes of cattle affected by either the paucibacillary or pluribacillary form of the disease. They yielded negative responses not only with healthy animals but also with those affected by tuberculosis (Mycobacterium bovis). Both immunohistological procedures proved to be as sensitive as or more sensitive than Ziehl-Neelsen staining and, in addition, to be endowed with species specificity.

Animals↗
PubMed1998

Antigoitrogenic effect of combined supplementation with dl-alpha-tocopherol, ascorbic acid and beta-carotene and of dl-alpha-tocopherol alone in the rat.

The effects of the vitamins dl-alpha-tocopherol, ascorbic acid and beta-carotene, free radical scavengers and lipid peroxidation inhibitors, were analyzed in male Wistar rats made goitrous by feeding a low iodine diet (< 20 micrograms iodine/kg) and perchlorate (1% in drinking water) for 4, 8, 16, and 32 days. Groups of control or goitrous rats received for at least 16 days before killing a diet containing 0.6% vitamin E (as dl-alpha-tocopherol acetate), 1.2% vitamin C (ascorbic acid) and 0.48% beta-carotene, either simultaneously (vitamin cocktail) or separately. This treatment led to a 5-fold increase of vitamin E in the thyroid gland, a 24-fold increase in the liver and a 3-fold increase in the plasma. In control rats, vitamin cocktail administration increased slightly the thyroid weight with little changes in thyroid function parameters. During iodine deficiency, administration of the vitamin cocktail or vitamin E alone reduced significantly the rate of increase in thyroid weight, and DNA and protein contents, as well as the proportion of [3H]thymidine labeled thyroid follicular cells, but not that of labeled endothelial cells. Plasma tri-iodothyronine, thyroxine, TSH levels, thyroid iodine content and concentration as well as relative volumes of glandular compartments were not modified. The proportion of necrotic cells rose from 0.5% in normal animals to about 2% after 16 days of goiter development. No significant protective effect of the vitamins was observed. These results suggest that these vitamins, particularly vitamin E, modulate one of the regulatory cascades involved in the control of thyroid follicular cell growth, without interfering with the proliferation of endothelial cells.

Animals↗
PubMed1997

Cyclic feeding behaviour and changes in hypothalamic galanin and neuropeptide Y gene expression induced by zinc deficiency in the rat.

Dietary zinc-deficiency induces a striking reduction and a cyclic pattern of food intake in rodents. To elucidate the mechanisms for these effects, we studied the hypothalamic content, synthesis, and distribution of galanin (GAL) and neuropeptide Y (NPY) during zinc deficiency and refeeding in the rat. In Wistar rats, three weeks of zinc-deprivation consistently induced a reduction and a cyclic pattern of night- and day-time food intake, as well as of water intake. This was accompanied in zinc-deficient (ZD) rats, and to a lesser extent in pair-fed (PF) rats, by a decrease of hypothalamic GAL mRNA concentration (CTR: 100 +/- 8, ZD: 61 +/- 4, PF: 78 +/- 2 arbitrary densitometric units, ADU, P < 0.01) and an increase of hypothalamic NPY (CTR: 100 +/- 11, ZD: 154 +/- 10, PF: 126 +/- 4 ADU, P < 0.05), without peptide modification. The two neuropeptidergic systems were not affected by the cycles of feeding, with the exception of the NPY-immunoreactivity in the suprachiasmatic nuclei (geniculo-hypothalamic tract), that was inversely correlated to the food intake in both ZD and PF animals. In a second experiment, we showed that zinc-repletion for 4 days suppressed the behaviour induced by a two-week zinc-deprivation, and reversed the increase of NPY mRNA in ZD animals. We finally demonstrated that zinc-deficiency induced a similar behaviour in Zucker rats. However, in these rats whose synthesis of NPY is constitutively up-regulated, no change of NPY synthesis was observed in ZD rats, suggesting that the increase observed in Wistar is adaptative rather than instrumental to the abnormal food intake. In conclusion, we have further characterized the cyclic feeding behaviour of the zinc-deficient Wistar rats, and shown in these animals a decreased activity of the GAL system and an increased activity of the NPY system, likely corresponding to a compensatory response of the two neuropeptidergic systems, as observed in food-deprived animals. As spontaneous food intake of ZD rats does not increase, a resistance to NPY could also be present. These behavioural and neuropeptidergic changes were partially reversed by reintroduction of zinc in the diet. In Zucker rats, the same behaviour occurred despite an insensitivity of the NPY system to the zinc-deficiency. In addition, we describe a nutritional regulation of the NPY-immunoreactivity in the geniculo-hypothalamic tract, that could constitute the substrate of circadian rhythm modulation by timed feeding.

Aging↗
PubMed1997

Costimulation of adenylyl cyclase and phospholipase C by a mutant alpha 1B-adrenergic receptor transgene promotes malignant transformation of thyroid follicular cells.

Proliferation of thyroid follicular cells is controlled by three intra-cellular cascades [cAMP, inositol 1,4,5-triphosphate (IP3)/Ca2+/diacylglycerol (DAG), and tyrosine kinases] that are activated by distinct extracellular signals and receptors. We had previously generated a transgenic mouse model in which the cAMP cascade was permanently stimulated in thyroid cells by an adenosine A2a receptor (Tg-A2aR model). In the present work, we have generated a transgenic model characterized by the chronic stimulation of both adenylyl cyclase and phospholipase C in thyroid follicular cells. The bovine thyroglobulin gene promoter was used to direct the expression of a constitutively active mutant of the alpha 1B adrenergic receptor, which is known to couple to both cascades in transfected cell lines. The expression of the transgene resulted, as expected, in the activation of phospholipase C and adenylyl cyclase, as demonstrated by the direct measurement of IP3 and cAMP in thyroid tissue. The phenotype resulting from this dual stimulation included growth stimulation, hyperfunction, cell degeneracy attributed to the overproduction of free radicals, and the development of malignant nodules invading the capsule, muscles, and blood vessels. Differentiated metastases were found occasionally in old animals. The development of malignant lesions was more frequent and of earlier onset than in our previous Tg-A2aR model, in which only the cAMP cascade was stimulated. These observations demonstrate that the cAMP and IP3/Ca2+/DAG cascades can cooperate in vivo toward the development of thyroid follicular cell malignancies.

Adenylyl Cyclases↗
PubMed1996

Selenium deficiency and thyroid fibrosis. A key role for macrophages and transforming growth factor beta (TGF-beta).

Free radical damage and fibrosis caused by selenium deficiency are thought to be involved in the pathogenesis of myxoedematous cretinism. So far, no pathway explains the link between selenium deficiency and tissue fibrosis. Pharmacological doses of iodine induce necrosis in iodine-deficient thyroids. Necrosis is much increased if the glands are also selenium-deficient, which then evolve to fibrosis. This rat model was reproduced to explore the role of selenium deficiency in defective tissue repair. At first, proliferation indexes of epithelial cells and fibroblasts were comparable between selenium-deficient and control groups. Then, in selenium-deficient thyroids the inflammatory reaction was more marked being mainly composed of macrophages. The proliferation index of the epithelial cells decreased, while that of the fibroblasts increased. These thyroids evolved to fibrosis. TGF-beta immunostaining was prominent in the macrophages of selenium-deficient rats. Anti TGF-beta antibodies restored the proliferation indexes, and blocked the evolution to fibrosis. In selenium deficiency, an active fibrotic process occurs in the thyroid, in which the inflammatory reaction and an excess of TGF-beta play a key role.

Animals↗
PubMed1996

Early occurrence of metastatic differentiated thyroid carcinomas in transgenic mice expressing the A2a adenosine receptor gene and the human papillomavirus type 16 E7 oncogene.

We report here the characterization of a transgenic mouse model (Tg-A2aR/Tg-E7) resulting from the coexpression of two oncogenic transgenes in the thyroid. The two transgenes (Tg-A2aR and Tg-E7) were placed under control of the thyroid specific thyroglobulin gene promoter, and directed the expression of either the A2a adenosine receptor that constitutively activates the cAMP pathway, or the E7 protein of the human papillomavirus type 16, that binds and inactivates the retinoblastoma susceptibility gene product (Rb1). Transgenic mice expressing both transgenes were generated by interbreeding the Tg-A2aR and Tg-E7 transgenic lines, generated and characterized previously (Ledent et al., 1992, 1995). These mice develop a larger goiter than that of the two parental lines, and a severe hyperthyroidism comparable to that observed in the Tg-A2aR parental line. The main feature of the Tg-A2aR/Tg-E7 mice is the rapid occurrence of malignant lesions, and the dissemination of malignant thyroid tissue through the blood stream, generating multiple differentiated and functional metastases in the lung. These metastases appeared as early as 2 months after birth and their frequency increased to 75% over 3 months. They were associated with the presence of large vascular lakes in the thyroid. Electron microscopy of the malignant cells revealed nuclear features similar to those of human thyroid papillary carcinoma. These mice, in which two oncogenes are co-expressed in the thyroid, represent the first genetic animal model developing metastatic differentiated carcinomas of the thyroid with a high frequency.

Animals↗
PubMed1996

The non-obese diabetic (NOD) mouse: an animal model for autoimmune thyroiditis.

The NOD mouse, an ideal model for insulin-dependent diabetes mellitus, is also useful to study the pathogenesis of autoimmune thyroiditis. Spontaneous thyroiditis greatly varies in frequency among NOD colonies, but Hashimoto-like thyroiditis can be induced in two experimental models: goiter involution after iodide administration and immunization by TSH receptor, described hereunder.

Animals↗
PubMed1995

Molecular cloning of an orphan G-protein-coupled receptor that constitutively activates adenylate cyclase.

A human gene encoding an orphan G-protein-coupled receptor named ACCA (adenylate cyclase constitutive activator) was isolated from a genomic library using as a probe a DNA fragment obtained by low-stringency PCR. Human ACCA (hACCA) is a protein of 330 amino acids that exhibits all the structural hallmarks of the main family of G-protein-coupled receptors. Expression of hACCA resulted in a dramatic stimulation of adenylate cyclase, similar in amplitude to that obtained with other Gs-coupled receptors fully activated by their respective ligands. This stimulation was obtained in a large variety of stable cell lines derived from various organs, and originating from different mammalian species. hACCA was found to be the human homologue of a recently reported mouse orphan receptor (GPCR21). The mouse ACCA (mACCA) was therefore recloned by PCR, and expression of mACCA in Cos-7 cells demonstrated that the mouse receptor behaved similarly as a constitutive activator of adenylate cyclase. It is not known presently whether the stimulation of adenylate cyclase is the result of a true constitutive activity of the receptor or, alternatively, is the consequence of a permanent stimulation by a ubiquitous ligand. The tissue distribution of mACCA was determined by RNase protection assay. Abundant transcripts were found in the brain, whereas lower amounts were detected in testis, ovary and eye. Various hypotheses concerning the constitutive activity of ACCA and their potential biological significance are discussed.

Adenylyl Cyclases↗
PubMed1995

Site-dependent pathological differences in smooth muscles and skeletal muscles of the adult mdx mouse.

This study presents a survey of the morphometric characteristics, the regeneration rate, and the extent of muscle dystrophy in several smooth and skeletal muscles from adult mdx mice, an animal model of the Duchenne muscular dystrophy (DMD). Smooth muscles from adult mdx mice showed neither cell necrosis nor fibrosis. As compared to control C57 mice, the thickness of the mdx smooth muscle was normal in the vascular and urogenital layers but significantly reduced in the digestive layers, a finding relevant to clinical reports of gastrointestinal dilatation in DMD patients, and suggesting that gastrointestinal dysfunctions should be systemically searched for in DMD patients. Adult mdx skeletal muscles, however, presented different patterns of muscle suffering: either absent (esophagus); very mild (trunk and limb muscles); or severe (diaphragm). In these three conditions we studied the fiber diameters, the nuclei locations, and the regeneration rate. From this comparative study, it seems that severe dystrophy occurs in muscle tissues showing large fiber diameter and peripheral location of the nuclei. We showed that this combination occurs in the mouse diaphragm which is thus a realistic model for human DMD muscles.

Animals↗
PubMed1995

Sex-steroid control of galanin in the rat hypothalamic-pituitary axis.

To further investigate how sex steroids regulate galanin (GAL) in the rat pituitary and hypothalamus, we examined the effects of prepubertal gonadectomy (Gx) and long-term (9 weeks) replacement with estradiol (E2) or testosterone (T) on pituitary and hypothalamic GAL concentrations in Wistar rats (5-6/group). Sham-operated animals served as controls (CTR). Pituitary GAL concentration was markedly higher in random-cycling CTR-females than in CTR-males (1391 +/- 247 vs 39 +/- 5 pg/mg protein, P < 0.01) and decreased after Gx only in females (20 +/- 3 pg/mg protein, P < 0.01). E2 strongly increased pituitary GAL in Gx-females and Gx-males (4470 +/- 365 and 3853 +/- 347 pg/mg protein, P < 0.01), whereas T had no effect. Inversely, hypothalamic GAL was higher in CTR males than in CTR females (5.4 +/- 0.3 vs 4.0 +/- 0.5 ng/mg protein, P < 0.05), and decreased significantly after gonadectomy in males (3.7 +/- 0.2 ng/mg protein, P < 0.01). The only steroid treatment that significantly modified hypothalamic GAL in Gx animals was administration of E2 to females (5.7 +/- 0.4 ng/mg protein, P < 0.01 vs non-treated Gx). We also studied in hypophysectomized (Hx) rats (8/group) the effects of sex steroids on hypothalamic GAL concentration and distribution. The low hypothalamic GAL concentration observed in male and female Hx rats (1.0 +/- 0.1 ng/mg protein) was significantly increased by T in males and in females (respectively, by 40% and by 50%, P < 0.02) and by E2 in males (by 60%, P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Expression of nitric oxide synthase isoforms in the thyroid gland: evidence for a role of nitric oxide in vascular control during goiter formation.

The thyroid gland is a highly vascular tissue, and its blood flow changes dramatically in various pathological conditions. Although the mechanisms regulating these changes in vascularity and blood flow are not well understood, candidate mediators include endothelin-1 (ET-1) and nitric oxide (NO). In the present study, we used a reverse transcriptase-polymerase chain reaction assay to determine which components of these vasoregulatory pathways are present in the thyroid and to analyze changes in gene expression in an experimental model of goiter formation and involution. Expression of messenger RNAs (mRNAs) encoding ET-1, ET receptors (ETA and ETB), ET-converting enzyme, and the three nitric oxide synthase (NOS) isoforms (NOS I, NOS II, and NOS III) was readily detected in the rat thyroid. After goiter formation was induced by thiouracil and a low iodine diet, there was increased expression of the genes encoding ET-related proteins (ET-1, 3.2-fold; ETA, 2.9-fold; ETB, 3.5-fold) as well as two of the three NOS isoforms (NOS I, 2.7-fold; NOS III, 4.9-fold). During iodide-induced involution, the ET-related mRNA levels remained elevated, whereas those of the two NOS isoforms returned to basal values. ET-converting enzyme, NOS II, and thyroglobulin mRNAs were minimally affected in this model, providing evidence for selective regulation of these genes. To assess whether NO plays a role in vascular changes during goiter formation, animals were treated with a NOS inhibitor, N-nitro-L-arginine methyl ester (NAME). NOS activity in the thyroid was inhibited by more than 75% after treatment with NAME. Thyroid hormone and TSH levels were unchanged. Although NAME had little effect on overall thyroid size, vascular expansion during goiter formation was decreased by 36%. We conclude that the thyroid gland expresses a complex network of vasoactive genes whose expression is regulated dynamically during thyroid goiter formation and involution. NO production and probably other locally produced vasoactive substances are involved in changes in thyroid vascularization.

Animals↗
PubMed1995

Effects of selenium deficiency on thyroid necrosis, fibrosis and proliferation: a possible role in myxoedematous cretinism.

It has been suggested that selenium deficiency is a co-factor to iodine deficiency in the pathogenesis of myxoedematous cretinism. The mechanism proposed is that the generation of hydrogen peroxide is greatly increased in iodine-deficient thyroid glands, and that selenium is involved in the control of hydrogen peroxide and its derived free radicals. This study was carried out to investigate the effect of the possibly impaired cellular defence mechanism associated with selenium deficiency on thyroid necrosis and tissue repair. For this purpose, we studied thyroid tissue from selenium- (SE-) and/or iodine-deficient (I-) rats before and after an acute toxic iodine overload. In I- thyroids, necrotic cells were numerous. Acute iodine administration increased this effect. Necrosis was associated with transient infiltration of inflammatory cells. In I-SE+ thyroids the tissue resumed its normal appearance. In I-SE- thyroid glands, the iodide toxicity was stronger, with greater necrosis and inflammatory reaction. The inflammation resolved but was replaced by fibrotic tissue. Fifteen days after the toxic overload, the connective tissue volume was twice the control value. Before iodide overload, the proportion of dividing cells was equal in I-SE+ and I-SE- thyroids. Three days after the iodide overload, this proportion was increased in I-SE+ thyroids but reduced in the I-SE- thyroids. Overall, the I-SE- thyroids had four times fewer dividing cells than the I-SE+ thyroids. In summary, selenium deficiency coupled to iodine deficiency increased necrosis, induced fibrosis and impeded compensatory epithelial cell proliferation. These results are compatible with histological and functional description of thyroid tissue from myxoedematous cretins.

Animals↗
PubMed1995

Two-step development of Hashimoto-like thyroiditis in genetically autoimmune prone non-obese diabetic mice: effects of iodine-induced cell necrosis.

The administration of a high iodide dose (HID; 10 micrograms/day) to goitrous mice is known to induce thyroid cell necrosis and inflammation, which, in most strains, is transient. In this study, we analyzed the effects of iodide in autoimmune prone non-obese diabetic (NOD) mice. Control NOD mice fed a standard diet (MID; 1 microgram I/day) or HID did not spontaneously develop thyroiditis. In NOD mice previously made goitrous, HID provoked thyroid cell necrosis and diffuse inflammation within 4 days. Inflammatory cells consisted of MHC-class II+ antigen-presenting cells, CD4+ T helper cells and CD8+ T suppressor/cytotoxic cells. After 96 days of treatment with HID, thyroiditis similar to Hashimoto's disease was obtained in 100% of the animals, with destruction of thyroid follicles, large clusters of T and B cells, and antithyroid antibodies in the plasma. When treating goitrous mice with MID, no cell necrosis was observed and no autoimmune thyroiditis was obtained. The early iodide-induced cell necrosis and inflammation may thus be considered as an important factor in the induction and persistence of autoimmune thyroiditis in individuals carrying a genetic susceptibility to autoimmune disease.

Animals↗
PubMed1994

Subtypes of Madin-Darby canine kidney (MDCK) cells defined by immunocytochemistry: further evidence for properties of renal collecting duct cells.

The Madin-Darby canine kidney (MDCK) cell line has been proposed as a model for studying intercalated (IC) cells of the renal cortical collecting duct. The IC cells are characterized by peanut lectin (PNA) binding capacity, carbonic anhydrase (CA) activity and Cl(-)-HCO3- exchange mediated by a band 3-related protein. It has been suggested that these properties are also expressed in MDCK cells. So far however, the nature of the specific protein involved in Cl(-)-HCO3- exchange, the type of CA isozyme and the relationship between these two characteristics and PNA binding, have not been investigated in MDCK cells by immunocytochemical methods. Using two antibodies raised against human erythrocyte band 3 protein and two against human erythrocyte CA I and II isozymes, our study provides evidence that a protein related to band 3 is expressed in about 5% of cultured MDCK cells; these band 3-positive cells do not bind PNA and are not reactive for CAI or CAII. About 30% of the MDCK cells bind PNA, two-thirds of which are also CAII-positive. A majority (about 65%) of MDCK cells is not reactive for the three markers used; their density is increased after incubation with aldosterone. These data indicate (i) that the Cl(-)-HCO3- exchange of the MDCK cells could be related to human erythrocyte band 3, (ii) that the CA activity of the MDCK cell line bears antigenic identity with the erythrocyte CA II isozyme and (iii) that the latter is always co-localized with PNA binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Pituitary-dependent hormonal regulation of galaninergic neurons in the rat hypothalamus.

To investigate whether pituitary-dependent hormones may regulate galanin (GAL) content, synthesis and distribution in the hypothalamus, female hypophysectomized Wistar rats were treated for 2 weeks with subcutaneous injections of thyroxine (T4, 2 x 1 microgram), bovine growth hormone (GH, 2 x 125 micrograms), cortisol (C, 50 micrograms), subcutaneous implants of beta-estradiol (E2, 5-mm implant, dilution 1:1), or with the combinations [T4+GH], [T4+GH+C+E2] or [T4+GH+C+E2 + rat PRL, 2 x 125 micrograms] (doses/100 g BW/day). Concentrations of GAL in the hypothalamus were measured by radioimmunoassay (RIA) and GAL mRNA abundance was quantified by Northern blot (6 rats/group); 2 rats/group were used for immunohistochemistry. Hypophysectomy caused decreases of hypothalamic GAL peptide and mRNA concentrations (by 70 and 50%, respectively; p < 0.05 vs. intact rats). GAL immunoreactivity disappeared in the median eminence (ME), but increased in the neurohypophyseal magnocellular neurons of hypophysectomized rats. Substitution with T4, GH, [T4+GH], C or E2 had no significant effect on total hypothalamic GAL peptide and GAL mRNA concentrations. A treatment combining [T4+GH+C+E2] increased hypothalamic GAL (1.9 +/- 0.1 vs. 1.2 +/- 0.1 ng/mg protein in untreated hypophysectomized rats; p < 0.01) and GAL mRNA concentrations (127 +/- 19 vs. 59 +/- 2 densitometric units in untreated rats, p < 0.001). Addition of PRL to this combined treatment had no further effect. Treatment with T4, GH, [T4+GH] or E2 enhanced GAL labeling in the ME of hypophysectomized rats. The effect of estrogens was restricted to the GnRH-rich lateral regions of the ME. The combined treatment with [T4+GH+C+E2] restored the ME GAL immunoreactivity to levels observed in intact rats. In contrast, the increased GAL labeling observed in magnocellular neurons after hypophysectomy was not influenced by any hormonal treatment. In conclusion, hypophysectomy leads to marked reductions of hypothalamic GAL and GAL mRNA concentrations, and of GAL immunoreactivity in the ME. These reductions are prevented in part by a combined hormonal treatment associating T4, GH, C and E2, but not by any hormone given alone. This suggests specific pituitary hormone-dependent regulation of the hypophysiotropic GAL neurons. In contrast, the increased GAL labeling in magnocellular neurons of hypophysectomized rats persists despite hormonal treatment and likely represents a lesional effect on the neurohypophyseal GAL system.

Animals↗
PubMed1994

Expression of the endothelin-1 gene in the rat thyroid gland and changes in its peptide and mRNA levels in goiter formation and iodide-induced involution.

Endothelin-1 (ET-1) is a major vasoconstrictor peptide, first found in endothelial cells, and later in many other tissues, including the thyroid gland. We analysed the expression of the ET-1 gene in the rat thyroid gland and changes in ET-1 mRNA and peptide levels in goiter development and involution, two circumstances characterised by vascular changes. Thyroid hyperplasia was induced in adult Wistar rats by feeding a low iodine diet (LID) supplemented with 0.25% thiouracil for 10 days, and LID alone for 2 further days (H.12 group). Involution was induced by injecting 100 micrograms iodide and refeeding a normal diet during 6 h, 12 h, and 24 h (I.6h, I.12h, I.24h groups). Rats fed a normal iodine diet were used as controls. A specific 488 bp cDNA corresponding to the known sequence of pre-pro ET-1 was found by RT-PCR from RNA extracts in all thyroid experimental groups, as well as in lung and kidney which were used as positive controls. RP-HPLC analysis showed that ET-1 immunoreactivity eluted similarly as mature ET-1. During hyperplasia, ET-1 mRNA and peptide levels were increased 3.5- and 5-fold respectively. The relative volume of the vascular bed was more than doubled. During iodide-induced involution, the glandular ET-1 mRNA level remained elevated. The concentration of ET-1 peptide increased and was significantly greater at 12 h involution than in the H.12 group. At this time, the capillary reticulum reverted to individual capillaries and the vascular bed was significantly reduced. These data demonstrate that the ET-1 gene is expressed in the rat thyroid gland and that the ET-1 mRNA and peptide levels are increased during thyroid hyperplasia and remain elevated during a phase of rapid iodide-induced involution. These data suggest that changes in ET-1 production may play a role in control of thyroid gland trophic regulation and vascularity.

Animals↗