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Biomedical subjects

B Conte-Devolx

Publications and source records attributed to B Conte-Devolx.

At least 37 records · Page 2Linked to original sources
PubMed1988

Characterization of corticotropin-releasing hormone receptors on human pituitary corticotroph adenomas and their correlation with endogenous glucocorticoids.

Specific receptors for CRH were identified in five freshly excised pituitary adenomas causing Cushing's disease. Their kinetic properties and mean affinity constant [1.45 +/- 0.38 (+/- SE) nmol/L] were comparable to the characteristics of rat and monkey anterior pituitary CRH receptors. No correlation was found between the immediate preoperative plasma and urinary cortisol levels and the number of pituitary adenoma CRH receptors, which ranged from 6-96 fmol/mg protein, unlike in rats, in which corticosterone modulates the number of anterior pituitary CRH receptors. The lack of correlation between the concentration of CRH receptors and plasma cortisol levels may reflect the inability of glucocorticoids to down-regulate CRH receptors in these tumors. Thus, corticotroph adenomas are resistant not only to the feedback actions of glucocorticoids on proopiomelanocortin synthesis and secretion but also to their actions on CRH receptors.

Adenoma↗
PubMed1987

Further studies on the effect of glucose concentrations and other oxidizable substrates upon ionic gradients and in vitro somatostatin release from rat mediobasal hypothalamus.

During in vitro incubation of rat mediobasal hypothalamus (MBH), potassium and sodium gradients were high in the presence of glucose, pyruvate, lactate or the mixture glucose and pyruvate; in the absence of substrate, the ionic gradients were markedly lowered and corresponding somatostatin release from MBH was maximal. The specific effect of glucose on somatostatin release from MBH was tested under normal tissue polarization, i.e. in the presence of pyruvate. Under these more physiological conditions, somatostatin release was submaximal and inversely related to glucose concentrations (within the range 0-7 mM).

Animals↗
PubMed1987

[Adrenal tumors of fortuitous discovery. 13 cases].

An adrenal mass without any clinical or biological symptom was accidentally discovered in thirteen patients. All patients underwent surgical exploration. After surgery, pathological studies showed lesions of corticosuprarenaloma (5 considered benign, 1 malignant and 1 uncertain) myelolipoma (2 cases), adrenal cyst, ganglioneuroma, haemangioma and lymphangioma (1 case each). Since no reliable preoperative investigations are yet available to assess the nature of adrenal masses, and since these may be due to benign or malignant endocrine tumours, their surgical removal is indicated.

Adrenal Gland Neoplasms↗
PubMed1987

[The anterior pituitary endocrine function in Parkinson's disease].

Dopamine exerts an inhibitory or stimulant action on some of the hormones produced by the anterior pituitary gland. The dopamine content of the hypothalamus is considerably reduced in patients with Parkinson's disease. We have tested the anterior pituitary endocrine function in such patients to evaluate the repercussions on this function of the dopaminergic deficiency: the secretion of pituitary stimulins was found to be unaltered both at baseline level and after pharmacological stimulation.

Aged↗
PubMed1987

Evidence for basal and stress-induced release of corticotropin releasing factor in the push-pull cannulated median eminence of conscious free-moving rats.

Fourteen adult male rats were successfully implanted in their median eminence with a push-pull cannula perfusing an artificial fluid at a rate of 13 microliters/min, to measure the release of corticotropin releasing factor (rCRF-41) under physiological conditions assessed by baseline plasma adrenocorticotropic hormone (ACTH) levels. In the basal conscious free-moving state, rCRF-41 release displayed a fluctuating pattern, with peaks about every 45 min at a mean value of 9.0 +/- 0.7 pg/15 min sample (n = 42) vs a mean trough value of 4.1 +/- 0.3 pg/sample (n = 44). Ether stress was followed by a striking rise in rCRF-41 release which generally lasted about 45 min and reached mean peak values of 54.3 +/- 3.2 pg/15 min sample (n = 7). These data constitute the first direct measurements of basal and stress-induced CRF releases in conscious unrestrained rats.

Adrenocorticotropic Hormone↗
PubMed1987

Effect of passive immunization against corticotropin-releasing factor (CRF) on the postadrenalectomy changes of CRF binding sites in the rat anterior pituitary gland.

The concentration of corticotropin-releasing factor (CRF)-binding sites decreases in the rat anterior pituitary after adrenalectomy; this change may be related either to a direct effect of the circulating glucocorticoids at the pituitary level or to a desensitization of CRF receptors through an increased CRG release in hypophysial portal blood. In order to examine the latter possibility we have measured plasma adrenocorticotropin hormone (ACTH) levels and the number of anterior pituitary CRF binding sites in sham-operated and 24-hour adrenalectomized rats after blockade of endogenous CRF by passive immunization with an antiserum anti-rat CRF (CRF-AS), or after injection of normal rabbit serum (NRS). In NRS-injected rats, after sham operation, plasma ACTH concentration increased (227 +/- 34 vs. 118 +/- 19 pg/ml in controls) without change in CRF-binding sites capacity (20.7 +/- 2.6 vs. 24.6 +/- 3.5 fmol/mg protein in controls). Adrenalectomy induced a large rise in plasma ACTH (785 +/- 89 pg/ml) and a decrease in the number of CRF-binding sites (12.2 +/- 1.7 fmol/mg protein). After CRF-AS injection, plasma ACTH was normalized in sham-operated animals (149 +/- 24 pg/ml) and significantly reduced in adrenalectomized rats (472 +/- 76 pg/ml); the adrenalectomy-induced decrease in the number of CRF-binding sites was unaffected by the CRF-AS administration (12.2 +/- 1.7 fmol/mg protein). The administration of dexamethasone to adrenalectomized rats significantly reduced plasma ACTH concentrations (23.3 +/- 10.6 pg/ml) and prevented the loss in CRF-binding sites capacity (20.7 +/- 1.3 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenalectomy↗
PubMed1987

The corticotropin-releasing factor release in rat hypophysial portal blood is mediated by brain catecholamines.

In order to study the involvement of the hypothalamic corticotropin-releasing factor (CRF) in catecholamine-induced adrenocorticotropin (ACTH) secretion, we have measured CRF levels in rat hypophysial portal blood (HPB) after the pharmacological destruction of the ventral noradrenergic bundle (VNAB), using 6-hydroxydopamine (6-OHDA) stereotaxically injected into the VNAB. CRF levels in HPB were measured by radioimmunoassay, and the effects of 6-OHDA injection were controlled by the determination of catecholamine concentrations in the total hypothalamus. VNAB lesions induced a dramatic decrease in norepinephrine and epinephrine hypothalamic concentration. The CRF levels in HPB were also significantly reduced. These results suggest that central catecholamines exert a direct stimulatory control on the CRF release and play a major role in stress-induced ACTH secretion.

Adrenocorticotropic Hormone↗
PubMed1987

Effects of chronic maternal dexamethasone treatment on the hormones of the hypothalamo-pituitary-adrenal axis in the rat fetus.

Different hormones of the hypothalamo-pituitary-adrenal axis (corticotropin-releasing factor, adrenocorticotropic hormone, corticosterone) were measured in brain pieces (stalk, median eminence, hypothalamus), hypophyses, adrenals and plasma of 21-day-old rat fetuses from mothers which were given either plain tap water or water containing dexamethasone acetate (10 micrograms/ml) from day 15 to 21 of gestation. Dexamethasone induced drastic reduction of body weight (-66% vs. controls), severe atrophy of the adrenals (-83%) and a sharp drop in their corticosterone content (-74%). Fetal plasma corticosterone levels were below the lower limit of detection of the competitive corticosteroid-binding globulin (CBG) radioassay (less than 0.01 microgram/ml). Both atrophy and severe reduction of the adrenal activity in fetuses from dexamethasone-treated females were in good correlation with a drastic decrease in plasma adrenocorticotropic hormone (ACTH) levels which were below the lower limit of detection of the radioimmunoassay (RIA) used (less than 10 pg/ml) and a significant reduction in pituitary ACTH content (-93%). The low corticostimulating activity of the fetal hypophyses was associated with a drop in both corticotropin-releasing factor (CRF) hypothalamic content (-57%) and concentration (-67%). The effects of dexamethasone on plasma and pituitary ACTH concentrations in 21-day-old fetuses were compared to those, previously reported, of encephalectomy and decapitation performed on day 16 of gestation. The reported data were consistent with the present results, suggesting both pituitary and hypothalamic sites for the in vivo inhibiting action of dexamethasone on the rat hypothalamic-pituitary-adrenal axis in late gestation.

Adrenocorticotropic Hormone↗
PubMed1986

[Characterization and modulation of anterior pituitary binding sites for rat corticotropin releasing factor (r-CRF)].

Specific binding sites for rat CRF (r-CRF) have been characterized on rat anterior pituitary membranes. The binding of the radioiodinated analog of r-CRF (125I Tyr-r-CRF) was time, temperature, pH and protein dependent. No interaction was found with other neurohormones except with Arginine Vasopressin, but at supra physiological levels. Two classes of specific binding sites (high affinity and low affinity) for r-CRF were identified. Bilateral adrenalectomy provoked, since the 24th hour and up to 7 days, in addition of an increase of ACTH plasmatic levels, an abolition of the high affinity binding site; corticosterone treatment reversed these changes. This finding suggests that circulating glucocorticoids may control the anterior pituitary binding sites for CRF, either by a direct action on the anterior pituitary, or by a modulatory effect on hypothalamic CRF secretion.

Adrenalectomy↗
PubMed1985

Corticoliberin, somatocrinin and amine contents in normal and parkinsonian human hypothalamus.

We have compared hypothalamic contents of various neurotransmitters (dopamine (DA), norepinephrine and serotonin) and their metabolites (dihydroxyphenyl acetic acid, homovanilic acid, 5-hydroxyindoleacetic acid) in post-mortem human controls and parkinsonian hypothalami. Neurotransmitters and their metabolites were measured in 0.1 N HCl hypothalami extracts using electrochemical detection after high performance liquid chromatography. Using specific radioimmunoassays we have also measured corticoliberin and somatocrinin contents in these hypothalami. Despite a 50% decrease of DA contents in parkinsonian hypothalami, no variations of corticoliberin and somatocrinin contents were found: 16.6 +/- 1.78 pg/mg tissue in Parkinson disease vs 16.71 +/- 1.89 in controls for human corticotropin-releasing factor (hCRF 1-41) and 37.38 +/- 11 vs 45.16 for human growth-hormone-releasing factor (hGRF 1-44).

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

[Corticotropin releasing factor].

The search for a neurohormone specifically controlling ACTH secretion resulted in the discovery of the corticotropin-releasing factor (CRF). This factor, located mainly in a paraventricular-infundibular hypothalamic tract, stimulates ACTH synthesis and secretion through a cAMP-dependent mechanism. The corticotropin-releasing factor is the predominant component of a complex control system of adrenal cortex secretion, which also includes catecholamines and the antidiuretic hormone. Its specificity as stimulant of the corticotropic function makes it an extremely useful tool for physiological and physiopathological studies of the hypothalamus-pituitary-adrenal cortex axis regulation.

Adrenocorticotropic Hormone↗
PubMed1985

[Caudal epidural anesthesia in children. Study of endocrine changes].

Changes in serum levels of corticotrophin (ACTH), immunoreactive beta-endorphin, antidiuretic hormone and cortisol were compared in children undergoing minor surgery under either general anaesthesia with halothane or epidural anaesthesia by the caudal route. A rapid and major increase in hormone levels was observed under general anaesthesia but not under epidural anaesthesia.

Adrenocorticotropic Hormone↗
PubMed1985

[Passive immunization with an anti-oCRF41 immune serum inhibits the circadian increase of plasma ACTH in rats].

For 24 hrs. after i.v. injection of 1 ml of an undiluted immune serum raised against oCRF41, the diurnal surge of plasma ACTH dropped to a short-lived limited rise above baseline level. On the second day after injection, the ACTH level in treated rats rose to a subnormal level, although both plasma dilution of the immune serum and its binding capacity in the plasma remained unchanged throughout the experiment. Plasma corticosterone, on the contrary, displayed a normal circadian rhythm during the entire experiment. However, in animals given a second injection of 0.5 ml oCRF41 immune serum 32 hrs. after the first, both ACTH and corticosterone titers fell rapidly below their circadian minimal levels in controls. Concomitantly, the concentration of immune serum in the peripheral plasma, and its capacity to bind to oCRF, rose by 50%. The major role of CRF41 as a diurnal trigger of the circadian rhythm of ACTH is discussed, as well as the limits of passive immunization.

Adrenocorticotropic Hormone↗
PubMed1979

[Distribution of thyrotropin releasing hormone (TRH), alpha-melanocyte-stimulating hormone (alpha-MSH) and somatostatin in the skin of the green frog (Rana esculenta)].

High concentrations of Thyrotrophin-Releasing Hormone (TRH) have been found in the dorsal skin of the Frog Rana esculenta, lower levels being measured in the ventral skin. alpha-MSH and somatostatin were undetectable in these tissues. Nor was TRH detected in the blood of these animals. The concentration of somatostatin in the pancreas was similar to that of the hypothalamus and twice or one hundred times higher than in the intestine or stomach respectively.

Animals↗
PubMed1979

Immunoreactive somatostatin in rat hypophysial portal blood.

Somatostatin levels have been determined by RIA in hypophysial portal blood of pentobarbital-anesthetized male rats. In most animals, immunoreactive somatostatin (SRIF) levels were higher in hypophysial portal blood than in systemic blood. In euthyroid rats, the mean level was 158 +/- 27 pg/ml (n = 8); SRIF was undetectable (less than 30 pg/ml) in systemic blood of these rats. It is suggested that endogenous SRIF was not degraded during the collection of stalk blood, since synthetic SRIF is stable when incubated in rat serum during 4 min at 37 c and 2 h at 0 C, i.e. under the conditions the blood was kept during the collection. SRIF in hypophysial portal plasma had the same immunoreactivity with a specific antiserum against SRIF as did synthetic SRIF. Gel filtration of hypophysial portal plasma revealed two immunoreactive peaks, the major one corresponding to synthetic SRIF, the smaller one representing a larger molecular form. Thyroidectomy and excess of T4 did not modify the levels of SRIF in hypophysial portal blood, suggestinc SRIF is stable when incubated in rat serum during 4 min at 37 C and 2 h at 0 C, i.e. under the conditions the blood was kept during the collection. SRIF in hypophysial portal plasma had the same immunoreactivity with a specific antiserum against SRIF as did synthetic SRIF. Gel filtration of hypophysial portal plasma revealed two immunoreactive peaks, the major one corresponding to synthetic SRIF, the smaller one representing a large molecular form. Thyroidectomy and excess of T4 did not modify the levels of SRIF in hypophysial portal blood, suggesting that the feedback of thyroid hormones on TSH secretion does not involve changes in the secretion of SRIF by the hypothalamus.

Animals↗
PubMed1979

[Systematic evaluation of 8 arginine vasopressin and neurophysins plasma levels in 10 patients with oat cells carcinoma of the lung (author's transl)].

Plasma AVP level, neurophysins and osmolality have been measured in 10 patients with oat cell carcinoma of the lung but without any biological signs of syndrome of inappropriate secretion of ADH (SIADH), before and 15 mn after an intravenous injection of Ethanol. No statistically significant difference was noted in the AVP, neurophysins and osmolality values between 10 patients with asymptomatic oat cell carcinoma and control population (10 normal volunteers, 12 patients with non neoplasic lung pathology and 10 patients with different lung carcinoma). We concluded that AVP and neurophysins cannot be considered as a good tumoral marker in the detection of oat cell carcinoma of the lung.

Arginine Vasopressin↗