pituitrin and Atrophy

To study the effects of microgravity on the mechanisms involved in the regulation of body hydrous status, total body water (TBW), plasma volume (PV), and its main regulating hormones (plasma renin, aldosterone, atrial natriuretic peptide (ANP), anti-diuretic hormone (ADH)) were determined, by isotopic dilution, Dill and Costill's formula, and radio-immunologic dosages, in 9 male subjects submitted to a 90-d head-down bed rest (HDBR). ADH was determined in 24 h urinary collection as well as osmolality, sodium, and potassium. Body mass decreased (-2.8 +/- 0.8 kg) as well as TBW(-7.2% +/- 0.9%, i.e., -2.6 +/- 0.7 kg) and PV (-4.7% +/- 1.8%). Renin and aldosterone were enhanced (+109.0% +/- 15.4% and +87.2% +/- 38.9%, respectively). Simultaneously, we observed a decrease in ANP (-33.2% +/- 20.4%). Other variables, including ADH, were not affected by HDBR. Body mass and TBW decrease (and consequently lean body mass) are associated with muscle atrophy. Renin, aldostrerone, and ANP modifications are well explained by the decrease in PV, which was not enough to induce ADH changes. It suggests that in man, the main regulatory factor for ADH secretion is osmolality, when PV is modestly and progressively decreased without arterial pressure modification, which was the case in the present protocol.

Topics: Adult; Aldosterone; Atrial Natriuretic Factor; Atrophy; Body Water; Body Weight; Head-Down Tilt; Hormones; Humans; Male; Osmolar Concentration; Plasma Volume; Radioisotope Dilution Technique; Renin-Angiotensin System; Vasopressins; Water-Electrolyte Balance; Weightlessness; Weightlessness Simulation

Multiple sclerosis (MS) is a complex neurodegenerative disease presenting with a diversity of clinical symptoms including palsy and cognitive impairment. We present a 59-year-old woman with a history of secondary progressive MS since 1987, who was referred to our department because of recent onset of confusion and polydipsia. Initial lab tests showed mildly elevated serum sodium levels and low urine osmolality. Under water deprivation, diuresis and low urine osmolality persisted and serum sodium levels rose above 150 mmol/l. Oral desmopressin resulted in normalisation of serum sodium as well as urine osmolarity, confirming a diagnosis of central diabetes insipidus. As drug-induced diabetes could be excluded, pituitary magnetic resonance imaging (MRI) was performed. A demyelinating lesion was detected in the hypothalamus. The patient was started on oral desmopressin treatment (0.2 mg/day). Fluid intake and serum sodium levels have since remained normal. In summary, we report the rare case of a patient presenting with diabetes insipidus due to progressive MS. Diabetes insipidus should be considered in MS patients who develop new onset of polydipsia.

Topics: Atrophy; Cognition Disorders; Confusion; Diabetes Insipidus; Female; Humans; Hyponatremia; Hypothalamus; Magnetic Resonance Imaging; Middle Aged; Multiple Sclerosis, Chronic Progressive; Polydipsia; Sodium; Vasopressins

We evaluated plasma osmolality (pOsm), thirst, and vasopressin response to hypertonic saline infusion in 14 patients with multiple system atrophy (MSA). This disease is characterized by the degeneration of noradrenergic neurons in the central nervous system and severe orthostatic hypotension. Seven patients were also characterized by the lack of vasopressin response to hypotension (group B) and seven by a preserved response (group A). In group A pOsm rose from 290 +/- 2 to 312 +/- 6 mosmol/kgH2O, vasopressin from 0.9 +/- 0.3 to 5.7 +/- 0.5 pmol/l, and thirst from 1.1 +/- 0.1 to 8.7 +/- 1.1 cm on the visual analog scale. After saline, patients drank 1,215 +/- 150 ml of water (no different from healthy controls). In group B patients' pOsm rose from 296 +/- 3 to 325 +/- 6 mosmol/kgH2O and vasopressin from 1.2 +/- 0.1 to 19.6 +/- 0.4 pmol/l (P < 0.01 vs. group A and controls). Group B patients had no thirst during saline and drank little after the challenge (175 +/- 50 ml; P < 0.01 vs. group A and control). Forced drinking decreased vasopressin in patients before changes in pOsm, showing that inhibitory afferents from oropharyngeal mucosa were intact. In MSA patients with altered afferent control of vasopressin there is a dissociation between the osmotic control of thirst and the osmotic control of vasopressin.

Topics: Afferent Pathways; Atrophy; Denervation; Drinking; Female; Hemodynamics; Humans; Hypotension, Orthostatic; Male; Middle Aged; Nervous System Diseases; Norepinephrine; Osmosis; Pressoreceptors; Saline Solution, Hypertonic; Sinus of Valsalva; Thirst; Vasopressins

The absence of hydrostatic forces, which results in body fluid shifts, and the absence of deformation forces on normally load-bearing tissues, appear to cause the principal disturbances found during and after space flight in the cardiovascular, fluid and electrolyte, erythropoietic, musculoskeletal, and metabolic systems. These alterations produce reduced body fluid volume, reduced musculoskeletal mass, and alterations in basal metabolism, resulting in the following consistent findings of space flight: weight loss, altered body composition, decreased orthostatic tolerance, and a compromised ability to deal with physical activity after returning from a space-flight environment. Specific changes include alterations in hydration status, resulting in a relative dehydration, loss of body calcium stores with a concomitant increase in urinary hydroxyproline, skeletal muscular atrophy, and a negative energy balance after prolonged space flight. Numerous endocrine changes have been determined during space flight, but more sensitive assay developed recently will allow careful determination of other hormone levels, and measurement of some of the primary changes that occur during the first hours of space flight. These results will be integrated into a working systems model of the physiologic response to weightlessness.

Topics: Atrophy; Body Weight; Calcium; Energy Metabolism; Glomerular Filtration Rate; Humans; Kidney; Muscles; Posture; Space Flight; Vasopressins; Vitamin D; Water-Electrolyte Balance; Weightlessness

Topics: Atrophy; Brain; Brain Diseases; Chlorpropamide; Diabetes Insipidus; Female; Humans; Leukemia, Lymphoid; Middle Aged; Pituitary Gland; Vasopressins

Topics: Aged; Atrophy; Blood; Brain Diseases; Chlorpropamide; Diabetes Complications; Diabetes Mellitus; Female; Fludrocortisone; Humans; Hyperpituitarism; Hyponatremia; Natriuresis; Osmolar Concentration; Tolbutamide; Urine; Vasopressins

Topics: Adolescent; Adult; Atrophy; Female; Humans; Kidney Function Tests; Male; Middle Aged; Potassium; Pyelonephritis; Renal Artery Obstruction; Sodium; Vasopressins

Topics: Adrenal Cortex Hormones; Adrenal Gland Diseases; Adrenal Glands; Adrenocorticotropic Hormone; Animals; Atrophy; Hypertrophy; Hypophysectomy; Kidney; Liver; Pituitary-Adrenal Function Tests; Postoperative Complications; Rats; Stomach; Thymus Gland; Vasopressins