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Passive immunization of pregnant rats with a specific antiserum to rat GRF (GRF-AS) is followed by a decrease in fetal serum GH on the 19th day of gestation. A significant reduction in serum GH is still observed in older fetuses and newborn rats. Pituitary GH content increases in 19- and 20-day-old fetuses after GRF-AS administration to their mothers. These results suggest that endogenous fetal hypothalamic GRF (or placenta GRF) play a physiological role in the secretion of pituitary GH as early as the 19th day of fetal life and may be responsible for the peak of GH release that occurs in fetuses at the end of gestation.

Brattleboro rats which lack endogenous vasopressin have been used to study the role of vasopressin as a corticotropin-releasing factor. Plasma ACTH, beta-endorphin, and corticosterone were measured by RIA in male and female Long-Evans and Brattleboro rats under the following conditions: unstressed, after ether stress, after nicotine injection, and after adrenalectomy. A significant reduction in the ACTH, beta-endorphin, and corticosterone responses to the different experimental procedures was observed in the Brattleboro rats. However, in this strain of rats, a significant increase in the release of all three hormones was obtained, suggesting that vasopressin has only a synergistic role in the regulation of their secretion.

The hypothalamic regulation of ACTH secretion has been reviewed. Recent biochemical investigations on corticotropin-releasing factor (CRF) suggest that CRF is present in the hypothalamus under two or more different molecular weight forms, their structure being not elucidated yet. Vasopressin has a CRF-like activity. However, contradictory results have been reported on the role of AVP as a physiological CRF. The synthesis of CRF appears to occur in a large hypothalamic area outside the median eminence. CRF-carrying fibers are thought to pass through the lateral retrochiasmatic area and project on the hypophysial portal vessels at the junction between the pituitary stalk and the median eminence. Conflicting data have been published on the influence of monoamines on ACTH secretion. In the dog, ACTH release is inhibited by the alpha-adrenergic receptors, this effect being not as clearly demonstrated in other species. The stimulation of nicotinic and muscarinic receptors followed by increased ACTH secretion. Glucocorticoids appear to lower ACTH secretion through an action at both the hypothalamic and pituitary levels.

We have characterized the opiate binding sites on the membranes of bovine adrenal medulla and human pheochromocytoma, using 3H-labeled D-Ala2-D-Leu5-enkephalin ( [3H]DADLE), [3H]etorphine, and [3H]ethylketocyclazocine ( [3H]EKC). Binding was stereoselective in both membrane preparations. Association and dissociation kinetics showed that steady state was achieved after 20-25 min of incubation at 37 degrees. Saturation experiments were performed in the absence or in the presence of morphiceptin (1 microM), which masks the mu sites, D-Ser2-Leu-enkephalin-Thr6 (100 nM), which masks delta sites, or DADLE (5 microM), which was found to mask the delta, mu, and benzomorphan receptor. Taking into consideration the affinities of the three radioligands used (DADLE identifying the delta and mu sites when used in the nanomolar range; etorphine identifying the delta, mu, and benzomorphan sites; EKC identifying the delta, mu, kappa, and benzomorphan receptors) we have characterized pharmacologically the opiate sites present on bovine and human membranes. Human pheochromocytoma membranes contained (a) mu binding sites (15 fmoles/mg of protein, KD [3H]etorphine 1.0 nM, [3H]EKC 5.4 nM, [3H]DADLE 5.6 nM); (b) kappa sites (41 fmoles/mg of protein, KD [3H]EKC 1.0 nM); (c) benzomorphan sites (115 fmoles/mg of protein, KD [3H]etorphine and [3H]EKC 1.0 nM). On bovine membranes we have detected (a) delta binding sites (10 fmoles/mg of protein, KD [3H]DADLE 0.7 nM); (b) mu sites (24 fmoles/mg of protein, KD [3H]DADLE 2.9 nM, [3H]etorphine 0.2 nM, [3H]EKC 3.4 nM); (c) kappa sites (12 fmoles/mg of protein, KD [3H]EKC 0.4 nM); (d) benzomorphan sites (80 fmoles/mg of protein, KD [3H]etorphine 0.2 nM, [3H]EKC 1.3 nM); (e) a residual high-affinity (20 fmoles/mg of protein, KD 0.2 nM) site identified by [3H]etorphine in the presence of 5 microM DADLE. The relative proportions of benzomorphan sites were equal in both tissues (65% of the high-affinity sites) whereas kappa receptors were more abundant on human membranes (25%) than on bovine membranes (9% of the high-affinity sites).

Somatostatin levels have been determined by radioimmunoassay in hypophysial portal blood of pentobarbital-anesthetized male rats. In euthyroid rats, the mean level was 158 +/- 27 pg/ml (n = 8); somatostatin was undetectable (less than 30 pg/ml) in systemic blood of these rats. Thyroidectomy and excess of T4 did not modify the levels of somatostatin in hypophysial portal blood.

Opiate binding sites have been characterized on membranes from bovine adrenal medullas and six human pheochromocytomas. In human tumors, large variations in site distribution were observed. Kappa and benzomorphan sites represented the majority of the sites detected. The heterogeneity of the opiate sites on these tissues could explain the observed differences in the pharmacological responses to opiates of cultured cells from these tissues. Furthermore, adrenal medullas could be a good model for the study of the kappa site action at the cellular level.

Significant concentrations of enkephalins are present in the adrenal medulla, notably in man, ox and dog. High molecular weight peptides precursors of enkephalin pentapeptide can also be demonstrated in the same tissue. Although the biosynthesis of enkephalins has not yet been completely elucidated, it seems to follow a pathway different from that of beta-endorphin. The secretion of enkephalins is regulated by the same mechanisms as the secretion of catecholamines. Enkephalins act locally by modulating catecholamine release, but since they are released into the systemic circulation, another, still ill-defined hormonal action is possible.

A 58-yr-old man presented a Cushing's syndrome gradually developed for two years, and a cervical tumor. Urinary free cortisol and 17-hydroxy-corticosteroids were elevated and non suppressible under high dose dexamethasone (8 mg a day X 2 days). Plasma calcitonin (7,200 pg/ml), CEA (803 ng/l), beta LPH (624 pg/ml), and CRF (29 pg/ml) were elevated. Total thyroidectomy revealed a medullary carcinoma of the thyroid. Postoperatively the Cushing's syndrome disappeared and plasma CRF became undetectable although plasma calcitonin remained elevated. One out of 3 CRF antisera tested for immunocytology was positive in 10 to 30% of the cells. In tumor extract, CRF (RIA) concentration was 4.75 ng/g. There was no detectable ACTH in the tumor by biochemical as well as immunocytochemical method. In the present report, the next evidences are--for the first time--simultaneously present to demonstrate an ectopic secretion of CRF by a medullary thyroid carcinoma: presence of CRF in systemic blood being undetectable after surgery; cure of the clinical and biological features of Cushing's syndrome after thyroidectomy; characterization of CRF immunoreactivity in tumor. Taken together, the radioimmunological and the immunocytochemical data suggest the production of several molecular forms of CRF.

In order to elucidate the physiological role of the 41 amino-acid residue corticotropin-releasing factor (41-CRF) on the secretion of ACTH, B-Endorphin and alpha-MSH, plasma levels of these peptides were measured by radioimmunoassay in intact and adrenalectomized rats, two hours after the injection of either 41-CRF antiserum (CRF-AS) or normal rabbit serum for controls. The administration of CRF-AS strikingly lowered the plasma ACTH levels in both intact and adrenalectomized rats. A statistically significant reduction of plasma levels of B-Endorphin was also observed in the same rats. However, the effect of CRF-AS on B-Endorphin release was less pronounced than the effect on ACTH release. No changes in plasma alpha-MSH levels were observed after passive immunization with CRF-AS. We conclude that, in the rat, 41-CRF plays a physiological role in the regulation of ACTH and B-Endorphin secretion, but is not involved in the regulation of alpha-MSH release from the pituitary gland.

Adrenal medulla has recently been shown to contain high concentrations of enkephalin immunoreactive peptides. In the present study, we report the levels of M-ENK and L-ENK in extracts from 6 cases of human pheochromocytoma. The molecular forms of M-ENK have been characterized by gel filtration chromatography and HPLC. mRNA extracted from one tumor has been proved to code for a 80,000 kilo daltons protein containing M-ENK sequence. M-ENK immunoreactive peptides are secreted in the culture medium of dispersed cultured cells of human pheochromocytoma. This secretion is stimulated when nicotine (10(5) M) is added to the medium. However, the level of plasma M-ENK in pheochromocytoma patients is not significantly different from normal patients. Data from Holaday and al. have established that naloxone (an opiate antagonist) has a beneficial role in shock. But the origin and meaning of plasma M-ENK remain to be established.

alpha-MSH secretion was significantly lowered in Rats after lesion of the mediobasal hypothalamus with microinjections of kainic acid. beta-Endorphin release after ether-stress was also reduced. In opposition, no significant change in basal and ether-stress ACTH secretion was observed.

The effect of neonatal hypothyroidism and neonatal caloric deprivation on brain TRH levels and serum and pituitary TSH levels has been determined in rats on the following postnatal days: 1, 5, 10, 15, 25, 40 and 60. After neonatal hypothyroidism, there was a slight reduction in brain TRH content although TRH concentration in the brain increased. Serum TSH was elevated at birth, suggesting that the feedback of thyroid hormones on the pituitary gland acts in rat fetuses. After neonatal caloric deprivation, a decrease in brain TRH content was observed along with a decrease in circulating TSH levels, however, there was no change in brain TRH concentration.

Two peptides have a strong corticotropin releasing factor (CRF) activity: arginine vasopressine (AVP) and a 41-residue peptide (41-CRF). Both peptides are present in high concentration in the PVN of the Rat, a zone of the hypothalamus at which electrical stimulation elicits ACTH release. Since homozygous Brattleboro Rats (Di/Di) congenitally lack endogenous AVP, it was of interest to compare the ACTH and corticosterone release after electrical stimulation of the PVN in Long-Evans (L.E.) and Di/Di Rats. In both L.E. and Di/Di Rats, there is a significant increase in plasma ACTH and corticosterone after electrical stimulation of the PVN. However, corticosterone levels are significantly lower in Di/Di than in L.E. Rats whether the Rats have been stimulated or not. It is concluded that a physiological CRF activity is present in the PVN of Di/Di Rats independently of the CRF like activity of AVP.

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).

A syndrome of chronic hypernatremia (range 148 to 161 mmoles/l) and partial hypopituitarism (growth hormone and gonadotropin deficiencies) is reported in a 27 year-old man with sarcoid hypothalamic involvement. The patient did not complain of thirst and spontaneous fluid intake was not sufficient to restore the serum sodium to normal. However, when larger amounts of water were given (50 ml/kg for 180 min), the plasma osmolality returned to normal values in 3 hours. Blood volume values were found subnormal on two occasions on free diet (63 and 74% of the theorical normal values) and plasma renin activity was elevated (22 ng/ml/hour). Plasma vasopressin (AVP) concentrations (range < 1 to 1.9 pg/ml) were inappropriately low for the degree of plasma osmolality and remained markedly subnormal when hypertonic saline was infused (NaCl 5%, 10 ml/min for 60 min). However, the secretory stores and hemodynamic control of AVP release were intact since a rise in plasma AVP to 10.8 pg/ml was observed after induction of arterial hypotension with sodium nitroprusside infusion. These results provide further direct evidence fo the dysfunction of the thirst mechanism and the osmotic contol of AVP release. They support the concept that osmoreceptor areas are anatomically distinct from the neurohypophyseal AVP secretory system and that neural inputs from baroreceptor and osmoreceptor cells are completely separated.

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.

Rat hypophysial portal blood, collected from the pituitary stalk, was extracted and enkephalins were assayed by different RIA. Met-Enk-IR and Leu-Enk-IR levels were 1635 +/- 470 pg/ml and 125 +/- 50 pg/ml, respectively. Using HPLC characterization, the presence in portal blood of Met-Enk, Leu-Enk, proenkephalins fragments and dynorphin1-17 has been demonstrated. An unidentified Met-Enk-IR peptide has also been found.

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.

The injection of haloperidol, a dopamine receptor blocker, was followed by a large increase of plasma ACTH and beta-endorphin-like immunoreactivity (beta-EI) in the rat. This effect was prevented when the rats were previously treated with corticosteroids. These results suggest that catecholamines inhibit ACTH and beta-endorphin secretion in the rat.

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.

A nosological entity, calloso-genital dysplasia, is described from a case of primary amenorrhoea with coloboma and total agenesis of the corpus callosum. Deficiency of the thalamic gonadotropic hormone secretion was elicited, together with normal or moderately elevated prolactinaemia, the significance of which is discussed. Thyrotropic, somatotropic and corticotropic functions were normal. It may be that the hypogonadotropic eunuchoidism of this 24-year old woman with normal olfaction evolved towards panhypopituitarism over a number of years, but in such a malformation that had not changed since birth the thalamic hypophysiotropic dysfunction seems to be fixed and stable. Unless a most unlikely coincidence occurred, the primary amenorrhoea seems to be related to the malformation. Agenesis of the corpus callosum with panhypopituitarism is well known, but this case is original in that the pituitary deficiency is very limited. A comparison with its mirror image, olfacto-genital dysplasia or Kallman's syndrome is tempting, but it remains to be documented anatomically by other cases.

Ether stress-induced ACTH and corticosterone secretion is similar in 60 days adrenal medullectomized and intact Long-Evans Rats. Passive immunisation with a 41-CRF antiserum impairs corticotropic function after stress. This decrease is more pronounced in adrenal medullectomized than in intact animals. These results suggest that epinephrine plays a minor role on the stress induced ACTH secretion. This role can be demonstrated only after immunoneutralisation of endogenous 41-CRF.

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.

Basal plasma dopamine (DA), Norépinephrine (NE) and Epinephrine (E) were determined in controls (n = 15) essential hypertension (n = 19) and Pheochromocytoma (n = 9). Plasma NE was significantly higher in essential hypertension than in control and in 5 cases, plasma NE or E was 3 SD above mean control values. In 8/9 pheochromocytomas DA, E or NE were significantly elevated. In 1 case, catecholamine levels were within normal range during normotensive period. When a provocative glucagon test (1 mg I.V) was performed in controls, there was no change in blood pressure DA and NE levels, but a significant increase in plasma E 2.5 and 5 min. after injection. Similar results were obtained in 8/10 cases of labile hypertension. However in 2 cases plasma NE or E increased significantly without elevation in blood pressure. In 3/4 pheochromocytomas under normotensive phase, blood pressure and plasma catecholamines increased significantly; however in 1 case, no change was observed.

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.

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.

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.

Using the radioimmunoassay (R.I.A.) for neurophysins (I.R.N.) described in 1969, we demonstrated a concomitant, rapid release of both A.D.H. and I.R.N. within the first minutes (2') of the i.v. infusion of nicotine in 11 patients with normal neuropituitary function and 1 patient suffering from a Schwartz-Bartter syndrome. There is a close relationship (r : 0,82, p less than 0.001) similar to that described by other authors, between peak levels of A.D.H. and I.R.N. in all the patients. Hence, we proved that our R.I.A. system is influenced by nicotine stimulated neurophysins (N.S.N.). The negative results previously published by two of us in 5 normal men could have been due to the length of the period between the beginning of the test and the first blood sampling (30 mn).

To explore a possible differential role of distinct catecholamine (CA) innervation sites in corticotropin-releasing hormone (CRH) secretion, especially under stress conditions, we compared the effects in adult female rats of selective CA denervation of either the whole hypothalamus, by a discrete pharmacological lesion of the ventral noradrenergic ascending bundle [VNAB; 3 micrograms of 6-hydroxydopamine (6-OHDA) in 0.2 microliter of vehicle, bilaterally] or of the paraventricular nuclei (PVN) alone (1 microgram of 6-OHDA in 0.2 microliter of vehicle, bilaterally). Although both procedures induced a similar dramatic fall in norepinephrine and epinephrine concentrations (-55 to -65%) measured by high-performance liquid chromatography in PVN punches, the VNAB lesion, unlike PVN denervation, depleted the median eminence (ME) of both amines (-80%). Concomitantly, the VNAB lesion led to a 97% reduction of the immunoreactive (ir) CRH-41 concentration in the hypophysial portal vessels, associated with a 64% fall in plasma adrenocorticotropic hormone (ACTH), and, in another group, with an 80% inhibition of ether stress-induced ACTH surge. The deletion of CA innervation of the PVN alone reduced irCRH-41 levels in the portal vessels by only 57% and plasma ACTH by 35%. This lesion did not significantly impair stress-induced ACTH release. These results suggest that the CA innervation of the hypothalamus exerts a stimulatory control on CRH-41-secreting neurons not only directly at the perikaryal level but also at other hypothalamic sites of VNAB innervation including peripheral contacts between the terminals of CA and CRH nerves in the external ME.

Plasma alpha-MSH, beta-endorphin and ACTH were measured at 60 days of age in rats which had been injected during the neonatal period with monosodium glutamate (MSG). Although the arcuate nucleus tuberoinfundibular dopaminergic and cholinergic system was lesioned by the MSG, no change in circulating alpha-MSH, ACTH and corticosterone levels was observed under basal conditions, after ether stress of adrenalectomy. In contrast, a moderate, but significant decrease in plasma beta-endorphin was noticed after MSG treatment.

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.

The influence of metabolic control on peripheral neuropathy was studied in a population of adult insulin-dependent diabetic patients. Motor conduction velocity (MCV), measured on the common peroneal nerve, was used as electrophysiological index of neuropathy. Following control of hyperglycaemia, rapid and significant improvement in MCV was observed in diabetics without renal or ocular complications, but not in diabetics presenting with these complications. This would suggest that peripheral diabetic neuropathy is governed by two different mechanisms and that one of these is metabolic, as it can be reversed by reinstating glucide balance.

To examine if down-regulation of CRH-induced ACTH release occurs in corticotroph adenoma cells as well as CRH-glucocorticoid interactions in these cells, we established primary cultures of pituitary adenoma cells obtained by transphenoidal surgery from five patients with Cushing's disease. To prevent binding of glucocorticoids by serum proteins, we used a serum-free medium containing insulin, transferrin, selenium, and epidermal growth factor. The latter was found to be essential for both basal and CRH-stimulated ACTH secretion. CRH acutely stimulated, in a dose-dependent manner, ACTH release by all adenomas studied, with an IC50 of 0.5 X 10(-9) mol/L. Prolonged exposure (10 days) to a half-maximal stimulatory concentration of CRH led to continuous stimulation of ACTH secretion. A 4-day incubation with cortisol induced a dose-dependent decrease in both basal and long term CRH-stimulated ACTH release, with no difference in the IC50 (1 X 10(-8) mol/L). These data suggest that long term exposure to CRH does not desensitize corticotroph adenoma cells. Thus, it is unlikely that long-acting analogs of CRH will be useful in the treatment of Cushing's disease. ACTH secretion from corticotroph adenomas is restrained by glucocorticoids; the sensitivity of these cells to the negative effect of glucocorticoids is not modified by long term stimulation with CRH.

Alterations in the secretion of iodothyronines, cortisol, testosterone and growth hormone have previously been described in anorexia nervosa. We have studied prolactin and gonadotropins secretion in 23 cases of anorexia nervosa. Prolactin secretion was normal. Modifications in gonadotropins release were observed. However they could not be always related to weight loss since amenorrhea could either precede weight loss or still be present after return of the weight to normal. In all cases, FSH release after LHRH stimulation was normal. No increase in LH levels was observed after LHRH injection when the weight was 70% below the ideal weight. With increasing weight, LH release progressively recovered and normal LHRH-induced LH release was obtained when the weight was above 90% of the ideal weight. At normal weight, the ratio of LH/FSH was normal in patients menstruating less than 3 months after the test, while the ratio was low in non-menstruating females. In conclusion, when the weight was insufficient basal levels of FSH and LH and responses after LHRH stimulation corresponded to a prepuberal stage. An increase in the LH/FSH ratio and a normal LH/FSH ratio preceeded the recovery of menstruations. In about 1/3 of the cases, such an evolution was not observed without any satisfactory explanation. Other factors than weight may be involved, especially when the amenorrhea persists after weight recovery.

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.

An experimental system allowing both the incubation and rapid transfert of rat hypothalamic slices has been developed in order to approach the regulation of CRF secretion. The release of CRF has been quantified by a specific radioimmunoassay. Under basal conditions, immunoreactive CRF release reached an optimum of 96.2 +/- 10.4 pg/3 hypothalami/20 min. A depolarizing concentration of KCl (56 mM) or veratridine (50 microM) applied for 20 min. induced a 222 and 257% increase, respectively, in CRF release. The in vitro CRF values released under basal and stimulated conditions are comparable to those of other hypothalamic neuropeptides. Furthermore, in vitro CRF release from the hypothalamus is in the same order of magnitude as in vivo CRF secretion estimated by hypophysial portal blood collection or median eminence push-pull cannulation.

Plasma adrenocorticotropic hormone (ACTH) and corticosterone were detectable in fetal plasma on day 16 of pregnancy. Thereafter, the levels of both hormones increased steadily in a parallel manner and reached a peak on day 19 of pregnancy. Administration of an antiserum anti-rat corticotropin-releasing factor (CRF) to pregnant rats was followed by a significant decrease in fetal plasma corticosterone as early as day 17. Plasma ACTH measured under the same experimental conditions on day 19 of gestation was also significantly decreased. Similar results have been obtained with fetal plasma collected from adrenalectomized pregnant rats, indicating that the plasma corticosterone decrease in fetuses after immunoneutralization of CRF reflects changes in fetal adrenal secretion and not a diminution of corticosterone transfer from the maternal to the fetal circulation. These results show that endogenous CRF begins to play a physiological role in the regulation of ACTH and corticosterone secretion as early as in 17-day-old fetuses. This effect may occur before the connections between the neurosecretory CRF axons and the hypophysial portal capillaries have been established. Therefore, endogenous CRF may enter the hypophysial portal circulation after intercellular diffusion in hypothalamic tissue.

3 cases of inappropriate vasopressin secretion during one case of anaplastic carcinoma of the lung, one case of carcinoma of the prostate with bony metastases and one case of acute intermittent porphyria are presented. The plasma levels of vasopressin, measured by radioimmunoassay were high. Treatment with demeclocycline was attempted in one case. The clearance of free water was positive but the treatment was poorly tolerated by the digestive tract.

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).