J.R. Ducharme

Pattern of adenohypophyseal hormone changes in male rats following chronic stress.

To delineate the pattern of adenohypophyseal hormone secretion following chronic stress, adult male rats were exposed daily to 6 h of cold, forced exercise or immobilization for 3, 6, 10, 15, 28 or 42 consecutive days. Groups of these animals were sacrificed at the end of the last stress sessions, and plasma growth hormone (GH), luteinizing hormone (LH), prolactin (Prl) and follicle-stimulating hormone (FSH) levels were measured by radioimmunoassay (RIA). Irresspective of the different stimuli used, long-term stress induced a morphologic and hormonal response characterized by decreased ponderal growth, adrenal enlargement, thymus involution and significant diminutions in GH, Prl and LH levels with no modifications in FSH titers. The magnitude and duration of these changes varied with the severity of the stressors.

Carbohydrate intolerance in children and adolescents with Turner syndrome

Carbohydrate homeostasis was evaluated in 41 girls, 6 to 20 years of age, with Turner syndrome by means of oral and intravenous glucose tolerance tests, as well as intravenous tolbutamide. Mean (±SE) glucose levels following oral glucose were higher at 60 minutes (162±5 vs 134±6 mg/dl, 2 P P P

Effect of Stress and Hypothalamic Deafferentation on the Secretion of Growth Hormone in the Rat

Stressful stimuli are known to inhibitthe secretion of radioimmunoassayable rat growth hormone (RGH). Groups of adult male rats submitted to one of three different types of hypothalamic deafferentation (total, incomplete, or frontal) were exposed to ether and auditory stresses at 1 week intervals. Ether and auditory stresses were equally effective in inhibiting the RGH secretion in controls and frontally deafferented rats. Ether stress inhibited the RGH values of completely deafferented animals, while auditory stress left these values unchanged; α-MT pretreatment blocked the effect of ether stress in such animals. Neither stress was able to modify the already low values of the incompletely deafferented rats; pentobarbital anesthesia induced a marked rise of RGH plasma levels in these animals. Base-line levels of RGH were significantly higher in frontally deafferented, and significantly lower in incompletely deafferented rats than those of controls. These data seem to indicate that ether stress is transmitted through a humoral, dopa-minergic pathway, while auditory stress follows a nervous pathway. In addition, extra-hypothalamic influences seem to modulate the secretion of RGH through frontal inhibitory and postero-lateral stimulatory nervous pathways.

Effects of thyrotropin-releasing hormone on prolactin, growth hormone and corticosterone secretions in adult male rats treated with pentobarbital or morphine

Thyrotropin-releasing hormone (TRH) injected either IP (10 mg/kg) or intraventricularly (10 mug/rat) antagonized the pentobarbital-induced secretion of prolactin (PRL). This effect was not blocked by propranolol. In thyroidectomized animals the effect was not apparent; tri-iodothyronine (T3) injection was however ineffective. The injections of luteinizing hormone-releasing hormone (LH-RH) and of melanocyte stimulating hormone release-inhibiting factor (MIF) were also ineffective. Of six TRH analogues, only those containing histidine antagonized pentobarbital-induced PRL release, but none modified plasma levels of growth hormone (GH) or corticosterone (B). Brain levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were not modified by TRH. Morphine-induced secretion of PRL and GH was also significantly antagonized by TRH. Since pentobarbital and morphine-induced hormonal changes are probably exerted through a central nervous system depressant action, these data indicate that TRH can influence brain activity through an extrapituitary mechanism.

Effects of Chronic Stress on Pituitary Hormone Release Induced by Combined Hemi-Extirpation of the Thyroid, Adrenal and Ovary in Rats

Morphologic and hormonal changes, induced by combined ablation of a thyroid lobe, one adrenal and one ovary, were studied over a 15-day period in rats, some of whom were subjected to 8 h of daily immobilization. The compensatory hypertrophy (CH) of the contralateral glands in non-stressed animals was associated with a significant increase in the plasma levels of LH (from the 1st to the 10th day), prolactin (PRL, from the 3rd to the 6th day), FSH (on the 3rd day) and corticosterone (from the 6th to the 15th day), whereas GH titers were not altered. Immobilization for 1, 3, 6, 10 or 15 days inhibited the b.w. gain, induced involution of the thymus, enhanced compensatory enlargement of the adrenal, and blocked the CH of the ovary and, to a lesser degree, of the thyroid. This chronic stressor produced a marked rise in plasma corticosterone, antagonized the surge of PRL, FSH and LH, and decreased the plasma levels of GH. On the basis of these morphological and hormonal variations, it appears that severe chronic stress in hemi-thyroidectomized-adrenalectomized-ovariectomized animals further increases the ACTH response but antagonizes the increased secretion of the other pituitary hormones.

Gigantism and hyperprolactinemia in polyostotic fibrous dysplasia (Mc Cune — Albright syndrome)

A case of Mc Cune-Albright syndrome is presented with the unusual combination of gigantism and hyperprolactinemia. Dynamic exploration of the endocrine functions suggests the presence of an autonomous pituitary adenoma as the cause of the abnormal hormonal findings. These were successfully normalized by radiotherapy to the pituitary gland.

Inhibition of Pentobarbital-Induced Release of Growth Hormone by Thyrotropin Releasing Hormone

TRH antagonized the GH releasing effect of pentobarbital anesthesia as well in normal as in thyroidectomized rats, and significantly increased plasma B levels in normal animals. This effect was also observed when TRH was administered into a lateral ventricle of the brain in ug amounts, and was suppressed by the beta-adrenergic receptor blocker propranolol. T3 also antagonized the pentobarbital-induced release of GH; however, plasma B levels were not modified, and the effect on plasma GH levels was not suppressed by propranolol.

Endocrine Effects of Brain Serotonin Depletion by 5,6-Dihydroxytryptamine in Prepuberal Male Rats

The effects of selective degeneration of brainserotoninergic nerve terminals by 5,6-dihydroxytryptamine (5,6-DHT) injected intraventricularly in prepuberal male rats were studied in 2 experiments. In

Adenohypophyseal Hormone Response to Chronic Stress in Dexamethasone-Treated Rats

The influence of dexamethasone treatment on the basal values of corticosterone, GH, prolactin (PRL), LH and FSH, as well as on the adenohypophyseal hormone response to chronic stress was studied in female rats. Dexamethasone acetate (25 micrograms/100 b.w.), given by gavage twice daily for 10 days, decreased the resting plasma levels of corticosterone, GH, LH and PRL, whereas the FSH titers remained normal. The secretion of ACTH (evaluated indirectly through corticosterone concentrations) and of GH appeared to be most sensitive to the suppressive effect of dexamethasone. The same hormonal response pattern was induced by 8 h of daily immobilization for 10 days, except that ACTH release was enhanced and the plasma LH titers dropped more drastically. Dexamethasone administration in combination with restraint did not alter the characteristic hormonal profile of chronic stress, despite the fact that ACTH secretion was completely blocked. These data suggest that the inhibition of PRL, LH and GH secretion following severe, chronic stress is not causally related to the sustained elevation of plasma ACTH.

Reduced Pituitary Volume in Children with Short Stature: Clinical and Radiological Correlates

A retrospective evaluation of 80 cases of growth retardation evaluated at the Hôpital Sainte-Justine of Montreal has revealed that 20 of them (25%; 15 boys and 5 girls) had a reduction of pituitary volume as revealed by high-resolution CT scanning of the pituitary gland. Of these patients, 8 had complete growth hormone (GH) deficiency, as evaluated by arginine infusion and L-Dopa-propranolol testing and nocturnal blood sampling, and 3 had GH neurosecretory dysfunction. Five patients had combined or multiple hormonal deficiencies. A statistically significant correlation was found between nocturnal plasma GH values and pituitary volumes. From this study it can be concluded that reduced pituitary volume is a frequent finding in growth-retarded children with hypopituitarism.