Interaction of vasopressin and oxytocin with human breast carcinoma cells.

The arginine vasopressin and oxytocin content of normal and cancerous human breast tissue were measured using radioimmunoassay. Both peptides were present in amounts greater than that found in the circulation, but no difference between normal and malignant tissues was found. Binding of [3H]oxytocin and [3H]vasopressin were characterized in human breast carcinoma cells (MCF7 cells). Binding of both hormones to MCF7 cells was specific and saturable, the vasopressin receptor found to be of the V1 subtype. Scatchard analyses of the data were linear, indicating a single high affinity, low capacity binding site for each hormone (vasopressin: KD = 47.4 +/- 1.6 nmol/liter, Bmax = 27,300 +/- 6,500 sites/cell; oxytocin: KD = 51.3 +/- 0.4 nmol/liter, Bmax = 87,000 +/- 4,000 sites/cell). The effects of vasopressin and oxytocin on the growth of MCF7 cells were assessed using protein accumulation and cell numbers. Vasopressin at 10-1000 pmol/liter was mitogenic for MCF7 cells, but higher doses (10 nmol/liter) were growth inhibitory. Oxytocin was also mitogenic for MCF7 cells but to a lesser extent than vasopressin. In conclusion, we suggest that vasopressin and possibly oxytocin may be important modulators of the growth of some human breast carcinomas.

Neurohypophysial hormones in the adrenal medulla.

Immunoreactive oxytocin and arginine vasopressin (AVP) were measured in the adrenal medulla of both rat and man as well as in tissue from two pheochromocytomas using highly specific RIAs. In all instances, oxytocin predominated over AVP. The concentrations of oxytocin ranged from 19.9-162.7 pg/g tissue, whereas those for AVP were 9.8-102 pg/g. These values are far greater than those found in plasma. The oxytocin- and AVP-related neurophysins were also present in large quantities in human adrenal medulla and pheochromocytoma. Identity of the peptides was confirmed by demonstrating parallel immunoreactivity with standard compounds and by the high performance liquid chromatographic profiles. In experiments carried out in rats, the source of the adrenal medullary AVP and oxytocin did not appear to be the paraventricular nucleus. It is postulated that the neurohypophysial peptides may have a regulatory function in the secretion of catecholamines.

Vasopressin in human cerebrospinal fluid.

Arginine vasopressin was measured by RIA in samples of plasma and cerebrospinal fluid (CSF) taken synchronously from 62 patients with proven or suspected disorders of the central nervous system in order to determine the relationship between the secretion of vasopressin into the systemic circulation and that into the CSF. In 12 patients without endocrine or brain disease, mean plasma values (+/- SD) were 2.8 +/- 0.7 pg/ml and CSF values were 2.4 +/- 0.7 pg/ml. Thirty-six patients with various intracranial disorders had plasma and CSF values which were both within the range of 1-4 pg/ml. Eight patients had raised plasma concentrations, but their CSF levels were within the normal range. One patient with posttraumatic diabetes insipidus and 2 patients with subarachnoid hemorrhage had concentrations of CSF vasopressin which were greater than plasma levels. These results indicate that a blood CSF barrier to vasopressin exists in man and that under certain pathological conditions excessive amounts of the hormone can be secreted into the CSF independently of that which is released into the blood, a finding which could have clinical significance in disorders of brain function.

Hypothalamic-pituitary function in patients with craniopharyngiomas.

Hypothalamic-pituitary function was investigated in 20 patients with craniopharyngioma, and all showed some degree of hypopituitarism. Pituitary-adrenal dysfunction was present in 50% of the patients whereas all but one had deficiencies of growth hormone and gonadotropin. Serum thyroxine was low in 13 patients, and in a further six there was an abnormal response of thyrotropin (TSH) to thyrotropin-releasing hormone (TRH). Prolactin levels were normal in over half the patients tested and only moderately elevated in the remainder. Gonadotropins failed to increase adequately after gonadotropin-releasing hormone (LRH) in all but one patient, and the response gave no indication of the predominantly hypothalamic site of the tumors.

Effects of arginine vasopressin (AVP) infusions on circulating concentrations of platelet AVP, factor VIII: C and von Willebrand factor.

To study the possible role of arginine vasopressin (AVP) in the control of haemostasis AVP infusions at 3 doses (0.1, 0.2 and 0.3 mU/kg/min) were performed in 6 male volunteers. Both plasma and platelet AVP concentrations rose in a dose-related manner. At doses of 0.2 and 0.3 mU/kg/min there was an increase in the plasma concentrations of both plasma Factor VIII and von Willebrand factor. The data support the hypothesis that AVP, by interacting with platelets and stimulating factor VIII and von Willebrand factor release, plays a role in the control of haemostasis.

Blood-cerebrospinal fluid barrier to arginine-vasopressin, desmopressin and desglycinamide arginine-vasopressin in the dog.

The passage of 125I-labelled arginine-vasopressin (AVP) and its analogues desmopressin (DDAVP) and desglycinamide arginine-vasopressin (DGAVP) into cerebrospinal fluid (CSF) has been studied in the dog. After intravenous injection or infusion of these peptides radioactive substances were found in the CSF in amounts ranging from 0.5 to 1.4% of the total plasma radioactivity. However, only DDAVP could be identified in the CSF as the unmetabolized peptide. This observation may be related to the long plasma half-life of DDAVP which was found to be 50 min, compared with a half-life of 13 min for AVP and 8 min for DGAVP. After the intranasal administration of either [3H]AVP or 125I-labelled AVP similar results were obtained. Radioactivity was again present in the CSF but no AVP could be identified. These observations showed that the intranasal route of administration provides no increased access to the CSF. The existence of a blood-CSF barrier to AVP is confirmed and indicates that the concentrations of the hormone normally found in CSF arise from sources other than the blood.

Arginine vasopressin and oxytocin in the bovine adrenal gland.

The concentrations of immunoreactive oxytocin and arginine vasopressin (AVP) and their respective neurophysins (NpI and NpII) were compared in bovine adrenal cortex and medulla. While the concentration of AVP was similar in both tissues there was more NpII in the medulla. The medulla also contained much more oxytocin and NpI than the cortex. The extracted AVP and oxytocin had identical retention times to those of the synthetic peptides on high-performance liquid chromatography (HPLC) and were biologically active in assays for antidiuretic and milk-ejection activity (with potencies of 310 units/mg and 340 units/mg respectively). Adrenal NpI and NpII behaved identically to commercially available neurohypophysial proteins on HPLC. Oxytocin, NpI and AVP were assayed in five subcellular fractions of bovine adrenal medulla prepared on discontinuous sucrose gradients. A high proportion of each co-localized with noradrenaline and adrenaline in the chromaffin granule fraction. Binding of [3H]AVP and [3H]oxytocin to crude bovine adrenal medulla membranes was dependent upon both time and temperature. The binding sites were specific and saturable: studies with the V1 AVP antagonist d(CH2)5Tyr(Me)AVP and the V2 agonist 1-deamino-8-D-AVP indicated that the AVP receptor was V1 in specificity. Scatchard plots showed that each ligand interacted with a single high-affinity, low-capacity binding site: oxytocin dissociation constant (Kd) 3.1 +/- 0.29 nmol/l, maximum binding capacity (Bmax) 89.6 +/- 18.4 fmol/mg protein (n = 3); AVP Kd 0.73 +/- 0.02 nmol/l, Bmax 26.5 +/- 8.3 fmol/mg protein (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the distribution of oxytocin and vasopressin in the rat brain.

While immunohistochemistry has been used extensively to map both oxytocin (OT) and vasopressin (VP) pathways in the brain, little information is available concerning the quantitative distribution of these hormones--particularly oxytocin. We have isolated oxytocin from extrahypothalamic regions of the rat brain and shown it to behave identically with standard oxytocin in radioimmunoassay (RIA) and on high-performance liquid chromatography. Using sensitive RIA we have measured and compared levels of both oxytocin and vasopressin in the rat brain. Both hormones are widely distributed, with the largest amounts outside the hypothalamus being found in the locus coeruleus. Considerable quantities of both peptides (but particularly oxytocin) are found in mesencephalic, pontine and medullary nuclei. This distribution is similar to that of the catecholamines, and the possible interaction of oxytocin and vasopressin with catecholaminergic pathways in the central control of various functions is discussed.

Localization of vasopressin in the rat brain.

The distribution of arginine vasopressin (AVP) in the rat brain was studied using a sensitive radioimmunoassay. The highest concentration of AVP was found in the hypothalamus. Individually, the supraoptic, paraventricular and suprachiasmatic nuclei contained in the order of 10% of the total hypothalamic content. Vasopressin was also found in the thalamus, medulla, cerebellum, amygdala, substantia nigra and hippocampus. Much lower levels were detected in the pons, spinal cord, frontal and occipital lobes and caudate putamen. No AVP could be detected in any other regions of the cortex or corpus callosum. Chromatographically the vasopressin found outside the hypothalamus is of a similar nature to that of hypothalamo-hypophysial origin. This study supports previous reports of extrahypothalamic localization of vasopressin by immuno-histochemical methods. It is clear that AVP is not confined to the hypothalamo-hypophysial axis, and the possibilities that this may reflect an involvement in brain function are discussed.

Effects of lesions in the hypothalamic paraventricular, supraoptic and suprachiasmatic nuclei on vasopressin and oxytocin in rat brain and spinal cord.

The content of arginine vasopressin and oxytocin in various extrahypothalamic sites of the rat brain and spinal cord was determined by specific radioimmunoassays after lesions had been made in either the paraventricular (PVN), supraoptic (SON) or suprachiasmatic nuclei (SCN). In some animals all 3 nuclei were destroyed together. The PVN provided a considerable amount of the vasopressin innervation of the solitary tract nucleus, and most of that in the spinal cord. Oxytocin was removed from some areas after lesions of the PVN and, again, most of this peptide was lost from the spinal cord. Lesions of the SCN did not appear to be followed by significant quantitative changes in either hormone in any of the areas studied. Lesions of the SON resulted in loss of oxytocin, particularly in the periventricular grey and some other areas, suggesting that extrahypothalamic projections from this nucleus may be more important than was previously assumed. Lesions of all 3 nuclei which included destruction of accessory hypothalamic nuclei resulted in a much more widespread loss of vasopressin and oxytocin, but there was preservation of both peptides in the dorsal raphe nucleus and much of those present in the locus coeruleus. It is concluded that the contribution of the classical hypothalamic nuclei to the extrahypothalamic content of vasopressin and oxytocin in rat brain is less than was originally believed, and that there are areas of the brain such as the locus coeruleus and dorsal raphe nucleus in which the source of these peptides may be outside the hypothalamus.

Differential release of vasopressin and oxytocin in response to abdominal vagal afferent stimulation or apomorphine in the ferret.

The aim of this study was to investigate whether direct afferent stimulation of the abdominal vagus could promote release of the neurohypophyseal hormones. The nucleus of the solitary tract is the major recipient of vagal afferent information, and this region of the brainstem may also be activated by stimulation of the area postrema. For this reason apomorphine, a D2 dopaminergic agonist which acts on the area postrema, and can evoke vasopressin secretion in man, was also investigated for its effect on vasopressin and oxytocin release. Our results show that vasopressin, but not oxytocin is released in vast amounts in response to electrical afferent stimulation of the abdominal vagus. Administration of apomorphine also evoked a massive vasopressin release with less marked effects on oxytocin. The possible functional implications of these results are discussed especially in the context of nausea and vomiting.

Vasopressin, oxytocin and neurophysins in the human brain and spinal cord.

The concentrations of arginine vasopressin, oxytocin, and their related neurophysins were compared in many areas of postmortem human brain and spinal cord using specific radioimmunoassays. In the hypothalamus the ratio of vasopressin to oxytocin was approximately 3:1, and in the extrahypothalamic areas of the brain the greatest amount of both peptides was present in the locus coeruleus, and to a lesser extent the periaqueductal grey. Vasopressin only was found in the substantia nigra, and globus pallidus. In the medulla, including the nucleus of the solitary tract, the dorsal nucleus of the vagus, and the nucleus of the spinal tract of the trigeminal nerve, the amount of oxytocin was greater than that of vasopressin. In the spinal cord oxytocin predominated over vasopressin to an even greater extent, and reached particularly high values in certain segments of the intermediolateral grey column and dorsal horn. Estrogen-stimulated and nicotine-stimulated neurophysins (ESN and NSN) were both found in large amounts in those areas of the brain and spinal cord where the concentrations of the nonapeptides were greatest, but when the molar ratios of ESN to oxytocin and NSN to vasopressin were compared there was an excess of ESN.

Extrahypothalamic vasopressin in human brain.

The distribution of arginine vasopressin immunoreactivity in post-mortem human brain was examined using a radioimmunoassay. The highest concentration was found in the hypothalamus but substantial amounts of vasopressin-like immunoreactivity were also found in the locus coeruleus, periaqueductal grey, substantia nigra compacta and reticulata and in lower concentrations in the globus pallidus. The extrahypothalamic vasopressin was immunologically and chromatographically similar to hypothalamic vasopressin. The possibility arises that the high levels of vasopressin in the locus coeruleus may relate to an effect on noradrenergic transmission.

Extrahypothalamic vasopressin is unchanged in Parkinson's disease and Huntington's disease.

Vasopressin immunoreactivity was measured post-mortem in the locus coeruleus and substantia nigra of 16 cases of Parkinson's disease and multisystem atrophy, 10 cases of Huntington's chorea and 28 normal controls. Amounts of vasopressin did not differ significantly (P greater than 0.05) between the 3 groups. Immunohistochemistry demonstrated vasopressin within nerve terminals. These data are consistent with an extrinsic vasopressin system in the human locus coeruleus and substantia nigra.

Thermal control of drug release by a responsive ion track membrane observed by radio tracer flow dialysis.

The combination of a responsive hydrogel with a rigid porous supporting structure yield a membrane with high mechanical strength and high on-off-permeability ratio. A membrane consisting of an ion track filter with a thermally responsive lining was prepared by penetrating a 19 micron thick foil of poly(ethylene terephthalate) (PET) with swift heavy ions at a fluence of 5 x 10(5) ions/cm2, followed by etching of the ion tracks to generate an ion track filter with 2.9 micron pore diameter, onto which a thin layer of poly(N-isopropylacrylamide) (NIPAAm) hydrogel was grafted. It was revealed that the mass flow of various molecules (water, chloride-, choline+, insulin, and albumin) through the membrane could be thermally controlled. The on-off-permeability ratio ranged between 3 and 10 increasing with molecular weight. Over a storage time of 5 months the permeabilities varied up to a factor of 2.6, while the on-off-permeability ratio and temperature sensitivity remained practically constant.

Domperidone, a DA2-specific dopamine antagonist, has no effect on the renal or haemodynamic response to atrial natriuretic peptide in man.

1. Animal experiments have suggested that the renal effects of atrial natriuretic peptide (ANP) are dependent on dopaminergic activation, predominantly of the DA1-receptor. In man, there is evidence of dependence on the DA2-receptor for the natriuresis produced by central blood volume expansion. 2. Six normal volunteers underwent infusions of alpha-human ANP preceded by domperidone (a DA2-antagonist) or placebo. Eight volunteers underwent a 3 h period of 10 degrees head-down tilt also preceded by domperidone or placebo. 3. Both the ANP infusion and head-down tilt produced a significant diuresis and natriuresis, neither of which was antagonized by the presence of domperidone. 4. The ANP infusion significantly reduced diastolic blood pressure and produced significant increases in the Doppler-measured aortic blood velocity variables of peak velocity and maximal acceleration. Domperidone had an independent effect of increasing blood pressure but did not appear to have a specific interaction with the haemodynamic effects of ANP. 5. Head-down tilt reduced mean arterial pressure and heart rate and increased maximal acceleration. Again, an independent effect of domperidone was seen on blood pressure. Heart rate and maximal acceleration showed similar changes in the presence of domperidone. 6. Domperidone does not antagonize the renal or haemodynamic effects of ANP and if dopaminergic activation is necessary for the renal action of ANP it is unlikely to be mediated by the DA2-receptor.

Chronic hypernatraemia and hypothermia following subarachnoid haemorrhage.

We describe a 30 year old man who developed chronic adipsic hypernatraemia and hypothermia following a subarachnoid haemorrhage from an anterior communicating artery aneurysm. Anterior pituitary function tests were normal. Hypothermia was demonstrated over 4 years with loss of the ability to control heat conservation despite body temperatures as low as 30 degrees C. He failed to experience thirst despite plasma sodium concentrations of up to 187 nmol/l and plasma osmolalities of up to 397 mOsm/kg. The slope of the plasma vasopressin-plasma osmolality curve indicated loss of the osmoreceptor. There was an absent vasopressin response to insulin-induced hypoglycaemia but a normal response to apomorphine. The apomorphine-stimulated immunoreactive vasopressin was shown to behave identically to the synthetic peptide on HPLC and was bioactive.

A comparison of head-down tilt with low-dose infusion of atrial natriuretic peptide in man.

1. Procedures that increase atrial pressure, such as head-down tilt, result in an increase in plasma atrial natriuretic peptide (ANP) and a natriuresis, but a direct cause-and-effect relationship between these two responses has not been established. This study was undertaken to compare the effects of head-down tilt with exogenous ANP on renal function. 2. Eight normal sodium-replete volunteers underwent a 3 h placebo infusion, a 3 h ANP infusion at 1.2 pmol kg-1 min-1 and a 3 h period of head-down tilt. Each procedure was performed on a separate day, in random order. 3. ANP and head-down tilt produced similar increases in sodium excretion (65 +/- 24 and 68 +/- 16%, respectively). ANP did not increase urine flow significantly more than placebo. Head-down tilt increased urine flow significantly more than placebo and ANP. 4. Plasma ANP rose from 8.1 +/- 1.0 to 11.4 +/- 2.5 pg ml-1 during head-down tilt and from 6.5 +/- 1.4 to 32.3 +/- 10.7 pg ml-1 with ANP infusion. 5. ANP infusion had no significant effects on systemic haemodynamics whilst head-down tilt increased cardiac output and reduced heart rate and an index of systemic vascular resistance. 6. ANP infusion, whilst achieving a natriuretic response similar to that of tilt, was associated with a 3-fold higher mean plasma ANP level. Although plasma ANP rose during both ANP infusion and tilt, there was a lack of correlation between natriuretic response and plasma ANP. 7. The results are not compatible with a direct cause-and-effect relationship between plasma ANP and sodium excretion during head-down tilt.

Bromocriptine treatment of males with pituitary tumours, hyperprolactinaemia, and hypogonadism.

Plasma prolactin concentrations were measured in thirty-four males with pituitary tumours and twenty-two patients (65%) were found to have hyperprolactinaemia. Plasma testosterone concentrations were subnormal in twenty-nine patients. Ten patients with hyperprolactinaemia were treated with bromocriptine; prolactin was restored to normal values in eight patients but testosterone secretion remained deficient. Two patients were resistant to bromocriptine. Some improvement in libido and potency was obtained after restoration of normal prolactin concentrations in four cases in spite of persistently low testosterone secretion. For maximal improvement in sexual function treatment with both bromocriptine and testosterone was required.