Estrogen-stimulated Neurophysin Research Articles

A study on blood levels of oxytocin and neurophysins during labor and lactation.

Plasma oxytocin (OT) and serum neurophysins (Nps), during labor and nursing, were measured by specific radioimmunoassay for the study of the physiological role of this hormone in human reproduction. OT levels markedly increased to 217.3 + 36.02 pg/ml (Mean + S.E) during labor as compared to 119.2 + 21.29 pg/ml in the third trimester. At delivery OT was 176.3 + 30.92 pg/ml in maternal venous blood and 207.5 + 62.90 pg/ml in the umbilical vein, respectively. Blood ESN (Estrogen Stimulated Neurophysin) levels during the third trimester were almost twice as high as during the first trimester. Serum NSN (Nicotine Stimulated Neurophysin) levels at delivery were higher than during pregnancy, especially the NSN concentration in the umbilical artery was higher than that in the umbilical vein. One month after delivery, ESN returned to the level of the first trimester. Both ESN and NSN levels during nursing were higher than the values found before and after nursing. These results clearly indicate that the hypothalamo-posterior pituitary system plays some roles during labor and lactation, and that useful interpretations of concomitant analysis of both OT and Nps could be made for the study of this system.

An Oxytocin Precursor Intermediate Circulates in the Plasma of Humans and Rhesus Monkeys Administered Estrogen

Estrogen releases into plasma the human oxytocin neurophysin, previously termed the estrogen-stimulated neurophysin. Because oxytocin and its neurophysin are synthesized as part of a common precursor, stimuli which release the hormone should also release neurophysin and vice versa. However, release of oxytocin with its neurophysin has been difficult to demonstrate by immunological assay in humans administered estrogen. Under this condition, the oxytocin immunoreactivity that is released with the oxytocin neurophysin is a novel peptide which is antigenically similar to oxytocin yet is not oxytocin. Co-release of the oxytocin-like peptide with oxytocin neurophysin suggested that the oxytocin-like immunoreactivity may be a partially processed form of oxytocin. To test this hypothesis the synthetic oxytocin precursor intermediates oxytocin-glycine (G), oxytocin-glycine-lysine (GK), and oxytocin-glycine-lysine-arginine (GKR), were tested for cross-reactivity with the various oxytocin antisera used in this laboratory to distinguish the oxytocin-like peptide from oxytocin. Oxytocin-G, but not oxytocin-GK or GKR, showed extensive cross-reactivity with the oxytocin antiserum (Ab 1), which is known to detect the oxytocin-like peptide of human plasma. Plasma from men and rhesus monkeys administered estrogen and from pregnant women was separated by HPLC and oxytocin Ab 1 immunoreactivity was eluted from the column with the same retention time as synthetic oxytocin-G. Estrogen releases an oxytocin precursor intermediate into the circulation of humans and monkeys and may exert an important effect upon posttranslational cleavage of the oxytocin prohormone. These observations suggest a heterogeneity in the intraneuronal posttranslational processing of the oxytocin precursor in estrogen-treated versus nonestrogen-treated primates.

Distribution in the Macaque Pineal of Nerve Fibers Containing Immunoreactive Substance P, Vasopressin, Oxytocin, and Neurophysins

The distribution of nerve fibers containing immunoreactive substance P (SP), estrogen-stimulated neurophysin (ESN), nicotine-stimulated neurophysin (NSN), oxytocin (OT), and vasopressin (VP) was examined in the epithalamic area of adult male and female macaques. Perfused or immersion-fixed epithalamic tissues, sectioned, and mounted on glass slides were processed through the avidin-biotin immunofluorescence method. Fibers containing immunoreactive SP were observed in the pineal organ along the periphery, in the perivascular space, and dispersed between the pinealocytes. Fibers were often observed in the pineal stalk region, and the habenular nuclei had high concentration of immunoreactive SP. Immunoreactive ESN fibers were observed in the stria medullaris, in the lateral habenula, in the pineal stalk, and in the pineal organ. Within the pineal, fibers containing ESN were present in the perivascular space, often concentrated in the walls of blood vessels, but also dispersed between pineal cells. Fibers containing OT, NSN, and VP were also present in the macaque pineal, but in lower quantities compared with fibers containing ESN. These studies show that the pineal of subhuman primates contain nerve fibers (ESN, NSN, VP, OT) of possibly hypothalamic origin. It also has a rich supply of SP fibers, which might be of habenula origin, peripheral parasympathetic ganglia origin, or both. The functional significance of these peptidergic nerve fibers remains to be determined. However, there are indications that they might be involved in regulation of blood flow and release of secretory products from the pinealocytes.

Ampholyte displacement and high pressure liquid chromatographic separation of the estrogen-responsive neurophysin from human plasma.

Estrogen-stimulated neurophysin (ESN) or oxytocin (OT)-neurophysin (Np) was measured in plasma of seven men before and after oral administration of 25 mg diethylstilbestrol (DES). Pre-DES levels of ESN averaged 0.93 +/- 0.3 (+/- SEM) ng/ml and increased to 29.8 +/- 6.5 and 25.4 +/- 5.1 ng/ml 24 and 48 h after DES treatment, respectively. To compare the estrogen-responsive Np in plasma with human OT-Np which is present in the posterior pituitary gland, the Np fraction of post-DES plasma was concentrated by double precipitation with ammonium sulfate and applied to ampholyte displacement and Sephadex G-75 columns. The Np fraction of this plasma extract contained ESN immunoreactivity (IR) but no nicotine-stimulated neurophysin-IR. ESN-IR of plasma and of an extract of human posterior pituitary eluted identically from a Sephadex G-75 column, indicating similar mol wt. The plasma extract containing ESN-IR eluted from the ampholyte displacement column at pH 4.3-4.2. No nicotine-stimulated Np (arginine vasopressin-Np)-IR was found in the plasma samples. ESN-IR in an extract of human posterior pituitary gland eluted from the ampholyte displacement column at the same pH as that of the ESN extracted from plasma. Peak ESN-IR-containing fractions from the ampholyte displacement were pooled, dialyzed, lyophilized, and reconstituted in appropriate carrier buffer for reverse phase high pressure liquid chromatography. The ESN-IR was resolved into two distinct ESN-IR peaks by high pressure liquid chromatography. Plasma and posterior pituitary gave identical pairs of peaks. Thus, the Np that is increased in human plasma in response to estrogen is identical to pituitary OT-Np, providing strong evidence that estrogen stimulates the human neurohypophysis.

Acute influence of cigarette smoke in platelets, catecholamines and neurophysins in the normal conditions of daily life.

Cigarette smoking is firmly linked to the occurrence of acute coronary events. In twenty-two healthy volunteers in normal conditions of daily life we studied the acute influence of smoking on the following parameters: beta-thromboglobulin, thromboxane B2, epinephrine, norepinephrine, estrogen-stimulated neurophysin, and nicotine-stimulated-neurophysin. Our results show that in our population and following our protocol, smoking did not induce platelet activation, thromboxane formation, catecholamine release or estrogen-stimulated-neurophysin secretion. However, smoking did provoke a significant increase of nicotine-stimulated-neurophysin (p less than 0.05) which reflects vasopressin increase and which might explain the high incidence of ischaemic accidents in cigarette smoking via the vasoactive properties of vasopressin.

High pressure liquid chromatographic separation of an oxytocin/arginine vasotocin-like peptide from the plasma of patients with chronic renal failure.

Levels of a novel oxytocin (OT)- and arginine vasotocin (AVT)-like peptide detected by one antiserum to OT (Pitt Ab-1) and one antiserum to AVT (Tor AVT) were recently found to rise in human plasma in response to administration of estrogen. The novel peptide rose in parallel with the estrogen-stimulated neurophysin (ESN). The mean level (+/- SEM) of ESN in plasma of 11 individuals with altered renal function (nondialyzed) was significantly higher than the level in individuals with normal renal function (4.2 +/- 0.9 vs. 1.1 +/- 0.04 ng/ml; P less than 0.01). In patients treated with hemo- or peritoneal dialysis, mean (+/- SEM) levels of ESN were 18.1 +/- 3.2 and 16.8 +/- 3.7 ng/ml, respectively. Levels of estradiol and estrone were not elevated and did not correlate with high levels of ESN. Levels of OT Pitt Ab-1, AVT, and ESN immunoreactivity were measured in plasma form nine patients undergoing hemodialysis and eight patients undergoing peritoneal dialysis. Mean (+/- SEM) levels of all three peptides were elevated (12.9 +/- 1.5 microU/ml, 32.1 +/- 6.7 pg/ml, and 13.5 +/- 4.0 ng/ml, respectively). ESN was significantly correlated with OT Pitt Ab-1 and AVT (R2 = 0.80; P less than 0.001). Plasma samples from the same patients were pooled, treated, and separated by reverse phase HPLC. The plasma contained a peak of immunoreactivity detected by Pitt Ab-1 and Tor AVT Ab. The position of the material was distinct from that of synthetic OT, AVT, or AVP and corresponded to the position of the novel OT-like peptide found in plasma of individuals given estrogen. The findings support parallel secretion of the OT-like peptide with ESN and represent the first disease state characterized by high levels of this OT- and AVT-like peptide.

Estrogen-stimulated neurophysin in chronic renal failure.

Estrogen-stimulated neurophysin (ESN) was determined by radioimmunoassay in three groups of patients with chronic renal failure: predialysis patients, patients on hemodialysis and patients on continuous ambulatory peritoneal dialysis. ESN levels were significantly elevated in all patients. ESN of these patients is undistinguishable from highly purified pituitary ESN. Immunological and physicochemical analyses of ESN in patients with renal failure suggest that the elevated plasma level is due to a failure of renal clearance. In addition, heterogeneity of urinary ESN, revealed by multiple immunoreactive peaks after gel filtration, indicates altered renal metabolism.

Detection of immunoreactive human placental oxytocin and its contractile effect on the uterine muscle.

Freshly obtained human placentas from various periods of gestation were quantitatively analysed for their immunoreactive oxytocin (OT) content and its biological activity was examined in a Magnus apparatus by utilizing rat uterus. The mean values for placental immunoreactive OT per gram tissue increased from the first to the second trimester, maintaining its high level to term. The total content of placental OT also increased continually from the beginning of pregnancy to term. Blood levels of estrogen stimulated neurophysin (ESN) and OT were concomitantly enhanced through gestation. Placental extract and synthetic OT showed similar peaks in the elution pattern of ion-exchange chromatography through a carboxymethyl cellulose column. Synthetic OT and placental extract induced marked uterine contraction in diestrous rats. However placental extract previously incubated with OT antiserum failed to induce this effect. Though detection of immunoreactive OT by immunoassay alone does not provide definite identification of pituitary and placental OT, the present study suggests that placental immunoreactive OT could have a contracting effect on the uterine muscle.

Oxytocin, vasopressin, and estrogen-stimulated neurophysin: daily patterns of concentration in cerebrospinal fluid.

The concentrations of oxytocin, arginine vasopressin, and estrogen stimulated neurophysin in cerebrospinal fluid of monkeys showed a daily fluctuation with high concentrations occurring during the light period. The patterns of oxytocin and estrogen-stimulated neurophysin in the cerebrospinal fluid were not observed in the plasma nor were they altered after the administration of a dose of estradiol that increased concentrations of estrogen-stimulated neurophysin in plasma. The disassociation between these cerebrospinal fluid and plasma patterns and values suggests that the secretory activity of neurons that release estrogen-stimulated neurophysin and oxytocin into the cerebrospinal fluid is controlled by mechanisms different from those that control their release into the plasma.

Elevation of oxytocin and the oxytocin-associated neurophysin in the plasma of normal women during midcycle.

A positive correlation was observed between the midcycle elevation of estrogen (E) and the level of oxytocin- and estrogen-stimulated neurophysin (ESN), the protein carrier of oxytocin, in the plasma of five of six women. The time of the maximal level of E was associated with a level of oxytocin significantly greater than that in either the early follicular or late luteal phase (P less than 0.025). Likewise, the level of ESN at midcycle was greater than the level of ESN in the early follicular or late luteal phase (P less than 0.01). Other than states of lactation or pregnancy, this is the only described cyclic secretion of oxytocin in humans. Since oxytocin chronologically correlates with a rise in the level of E at midcycle, a role for oxytocin in ovulation may be considered.

Nature of the immunoreactive neurophysins in ectopic vasopressin-producing oat cell carcinomas of the lung. Demonstration of a putative common precursor to vasopressin and neurophysin.

In an attempt to delineate the nature of the immunoreactive neurophysins in oat cell carcinomas of the lung with ectopic vasopressin production, tumor neurophysins were characterized by gel filtration and by electrophoresis. In all of the five tumor tissues, activities of both vasopressin and nicotine-stimulated neurophysin (NSN) determined by radioimmunoassay were demonstrated. A small amount of oxytocin as well as estrogen-stimulated neurophysin was detected in three of the tissues. When tissue extract was subjected to Sephadex G-50 gel filtration in 0.2 N acetic acid, the major portion of immunoreactive NSN emerged in the fractions corresponding to the molecular size of 10,000. The migration pattern of NSN in these fractions on electrophoresis was qualitatively the same as that of NSN extracted from human posterior pituitary glands. In addition to this major neurophysin, immunoreactive NSN with the molecular size of 20,000 was consistently demonstrated in three tumor extracts. This high molecular weight form of neurophysin represented 6.5--8.7% of total NSN immunoactivities in each tumor extract and its elution profile was not changed when analyzed under denaturating conditions in 6 M guanidine hydrochloride. On electrophoresis, it migrated near the gamma globulin region; however, the peak was broad suggesting that it consists of more than two different molecular populations. A substantial portion of the high molecular weight NSN appears to be a glycoprotein judging from its binding to concanavalin A. When the high molecular weight from of neurophysin was incubated with trypsin, essentially all of the activities were converted into NSN with the molecular size of 10,000. Moreover, an equimolar amount of vasopressin was liberated after the treatment, the elution pattern of which closely resembled that of synthetic arginine vasopressin. When a lower concentration of trypsin was used, some of the 20,000-dalton neurophysin exhibited activities of both NSN and vasopressin. Since the antivasopressin serum used in this study appeared to be directed toward the ring portion side of vasopressin, these results suggest that this 20,000-dalton neurophysin is, in all probability, a common precursor to vasopressin and neurophysin, and that vasopressin may be located in the middle of the precursor molecule.

Oxytocin in human plasma: correlation with neurophysin and stimulation with estrogen.

RIA for the measurement of oxytocin in human plasma is described. Extraction of oxytocin from larger peptides in plasma used acetone precipitation with a 75% +/- 2 SEM recovery of oxytocin. Nonspecific binding of the assay was less than 4%, and the minimum level of detection was 0.2 microunits/tube. No cross-reactivity was noted with neurophysins, arginine, or lysine vasopressin. The mean basal level (+/- SEM) of oxytocin in men was 1.80 +/- 0.07 microunits/ml and was not different in normal women (1.71 +/- 0.07 microunits/ml). Changes in posture had no effect on the levels of oxytocin. Samples obtained every 15 min over 4 h showed no pulsatile secretion of oxytocin. In women chronically receiving estrogen as an oral contraceptive, oxytocin was greater than normal, (4.59 +/- 0.51 microunits/ml; P less than 0.01). Estrogen-stimulated neurophysin was also elevated (8.45 +/- 1.99 ng/ml; P less than 0.005). Acute ingestion of estrogen caused an increase in the level of oxytocin in plasma by 12 h and a concomitant elevation of estrogen-stimulated neurophysin. When the neurophysin was isolated from plasma obtained from a subject after ingestion of estrogen, the neurophysin from plasma comigrated on a polyacrylamide gel with a human pituitary standard of estrogen-stimulated neurophysin. In the studies in which neurophysin was elevated, the correlation between the level of oxytocin and the level of estrogen-stimulated neurophysin in plasma was significant (P less than 0.01). The observation that estrogen administration stimulates the release of oxytocin and estrogen-stimulated neurophysin provides additional evidence that this neurophysin is the oxytocin-neurophysin of man.

Human neurophysins during pregnancy, puerperium and menstrual cycles.

To clarify the hypothalamo-posterior pituitary function during pregnancy, puerperium and menstrual cycle, investigations were performed to determine the levels of serum neurophysins by specific radioimmunoassays. Sera from 75 women during normal pregnancy, 17 during postpartum and 49 during the normal menstrual cycle were assayed for Estrogen Stimulated Neuro-physin (ESN) and Nicotine Stimulated Neurophysin (NSN). ESN, associated with oxytocin increased during pregnancy and the values decreased to non-pregnant levels after parturition. During menstrual cycle ESN showed three peaks. In contrast, NSN, associated with vasopressin was little changed throughout the menstrual cycle, pregnancy and the puerperium. In this study two neurophysins changed independently, suggesting the hypothesis of “one hormone-one neurophysin.” The data also would indicate the availability of measurement of these two substances on the study of the function of human neurosecretory system.

Endocrine Function in Female Rhesus Monkeys After Hypothalamic Disconnection

Fourteen adult female rhesus monkeys, 8 with regular menstrual cycles and 6 ovariectomized, were subjected to hypothalamic disconnection using a modified Halasz-type knife. Complete “islands” were produced in 5 animals. In 4 of these, the, “island” included the medial basal hypothalamus and the suprachiasmatic nucleus and its immediately adjacent preoptic area. None of the animals developed diabetes insipidus. The animals with complete “islands” doubled their body weights within 10 months. Four of these continued to show either spontaneous or estrogen-induced LH surges. An increase of serum estrogen-stimulated neurophysin concentrations accompanying the LH surge occurred in all animals. There was a loss in diurnal variation of cortisol in all monkeys. Basal prolactin levels were elevated in only one animal who had damage to the medial basal hypothalamic area. Although the prolactin response to TRH was not affected by the procedure, it was diminished in the ovariectomized animals. Growth hormone release af...

Presence of two neurophysins in the human pineal gland.

The tentative identification of two neurophysins in human pineal glands is reported. The presence of these carrier-proteins for neurohormones was demonstrated by two different radioimmunossays: one highly specific for human pituitary estrogen-stimulated neurophysin (h-ESN) and the second for pituitary bovine neurophysin II (b-NII). These neurophysins accounted for about 0.425% of the total soluble pineal proteins. They were eluted from Sephadex G-75 column with the same elution volume as 125I labeled h-ESN. Their dilution curves were parallel to the standard curves of h-ESN and b-NII, respectively. Electrophoresis on polyacrylamide gel separated two distinct neurophysins. The less anodic neurophysin corresponding to b-NII and the faster moving one to h-ESN. The two proteins were named human pineal neurophysins I and II (h-PNI and h-PNII) in the order of their electrophoretic mobility. Purification of pineal neurophysins by isoelectric focusing resulted also in the separation of two neurophysins: one, recognized by antibody against h-ESN with an isoelectric point (pI) of 4.6, the other recognized by antibody against b-NII with a pI of 4.9. The presence of neurohormone(s), assessed by radioimmunoassay for [8-arginine] vasopressin, was also demonstrated. Under optimal conditions for the association the neurophysin and the neurohormone were eluted from Sephadex columns as a complex. This complex could be dissociated in 0.1N formic acid and the neurophysin and the neurohormone separated on Sephadex G-75.

Physiologic control of two neurophysins in humans.

Two human neurophysins, nicotine stimulated neurophysin (NSN), and estrogen stimulated neurophysin (ESN) were assayed during physiologic maneuvers and pathologic states in man. NSN is thought to be associated with vasopressin and was elevated in some subjects by volume depletion, surgical stress, hypotension and hypertonic saline infusion. Overnight dehydration did not elevate NSN in spite of urinary concentration. NSN was elevated in some subjects with the syndrome of inappropriate secretion of antidiuretic hormone and when tested was unresponsive to administered water, alcohol or nicotine. ESN was elevated during estrogen administration, in pregnancy, in newborns and in patients with cirrhosis. NSN was also acutely increased at parturition. These data support the association of NSN with vasopressin although changes in NSN were found only with potent stimuli for vasopressin release. ESN may be associated with oxytocin but demonstration of this awaits knowledge of oxytocin physiology in humans.

Alcoholism: Its Effect on Hypothalamic Pituitary Gonadal Function

Both as the result of liver disease and of alcoholism per se, chronic alcoholics develop infertility, sterility, gonadal atrophy, hypoandrogenization, and feminization. The hypothalamic-pituitary abnormalities associated with alcoholism include hyperprolactenemia-increased estrogen-stimulated neurophysin levels, suppressed secretion of plasma gonadotropins, and loss of gonadotropin reserve. Several of the possible mechanisms potentially responsible for the development of these endocrine abnormalities have been discussed. The rational for suspecting that alcohol might interfere with either vitamin A metabolism of alter the redox state of the testes, thus affecting germ cell proliferation and steroidogenesis, has been presented. A possible mechanism for the sexual changes observed in chronic alcoholic men has been proposed. Much work remains to be done in this area before a complete understanding of the pathogenesis of these phenomena is obtained. The omission of any consideration of the effects of alcohol on sexual function in women is an admission of gross ignorance greatly in need of rectification. The necessity for couching a description of even the natural history of the syndrome in alcoholic men in conditional terms is a reflection of the limited state of the art. Nevertheless, it behooves the gastroenterologist, who is frequently called upon to be the primary physician for alcoholic men, to keep abreast of the nongastrointestinal medical consequences of alcohol addiction so that they can be recognized early and incorporated into long range medical planning designed to care for the chronic alcoholic patient.

PLASMA NEUROPHYSIN LEVELS IN MONKEYS

Specific radioimmunoassays for human neurophysins released in response to estrogen (estrogen-stimulated neurophysin, ESN) and nicotine (nicotine-stimulated neurophysin, NSN) have been used to measure two similar neurophysins in rhesus monkey plasma. As in the human, concentrations of rhesus monkey neurophysins in plasma were specifically produced a marked increase of plasma NSN concentrations in the monkey. Estradiol benzoate administered intramuscularly consistently produced an increase in plasma ESN concentrations in normal cycling and castrate monkeys. ESN response to estrogen was exclusively positive and occurred approximately 10 hours after an injection of estradiol benzoate intramuscularly. Plasma samples obtained throughout the mid-cycle were measured and a characteristic rise in estrogen and LH, and a more prolonged rise in ESN were found. Our data indicate that the ESN and LH responses to estrogen stimulation are temporally related events and that the assay of ESN in plasma may be of unique value as it directly reflects the hypothalamic response to changes in estrogen secretion.

Plasma neurophysin levels in monkeys: emphasis on the hypothalamic response to estrogen and ovarian events.

Specific radioimmunoassays for human neurophysins released in response to estrogen (estrogen-stimulated neurophysin, ESN) and nicotine (nicotine-stimulated neurophysin, NSN) have been used to measure two similar neurophysins in rhesus monkey plasma. As in the human, concentrations of rhesus monkey neurophysins in plasma were specifically produced a marked increase of plasma NSN concentrations in the monkey. Estradiol benzoate administered intramuscularly consistently produced an increase in plasma ESN concentrations in normal cycling and castrate monkeys. ESN response to estrogen was exclusively positive and occurred approximately 10 hours after an injection of estradiol benzoate intramuscularly. Plasma samples obtained throughout the mid-cycle were measured and a characteristic rise in estrogen and LH, and a more prolonged rise in ESN were found. Our data indicate that the ESN and LH responses to estrogen stimulation are temporally related events and that the assay of ESN in plasma may be of unique value as it directly reflects the hypothalamic response to changes in estrogen secretion.

Isolation, assay, and secretion of individual human neurophysins.

Human neurophysin was isolated from acetone-dried human posterior pituitaries and separated into two major neurophysin peptides by ion exchange chromatography and into four major peptides by preparative disk gel electrophoresis. Antisera raised in rabbits distinguished only two specific antigenic sites on the isolated neurophysin peptides. Individual sensitive and specific radioimmunoassays for two human neurophysins were developed. These assays were used to measure each neurophysin in unextracted human plasma. The two neurophysins are secreted independently in man. One assay measures a neurphysin that is specifically secreted in response to estrogen administration, estrogen-stimulated neurophysin (ESN). The other assay measures a neurophysin that is specifically secreted in response to cigarette smoking, nicotine-stimulated neurophysin (NSN). The mean ESN is 1.1 ng/ml plus or minus 0.7 SD in women and 1.0 ng/ml plus or minus 0.7 SD in men. The mean NSN is 0.9 ng/ml plus or minus 0.2 SD in women and 0.6 ng/ml plus or minus 0.3 SD in men. It is proposed that these may prove to be a specific human "oxytocinneurophysin," ESN, and a human "vasopressin-neurophysin," NSN.