Individual Neurophysin Concentrations in the Pituitary and Circulation of Humans

Abstract

Specific, homologous human neurophysin I and II radioimmunoassays were established and used to measure the individual, immunoreactive neurophysin concentrations in human plasma. Circulating levels of human neurophysin I in normal individuals were less than 1 ng/ml and neurophysin II levels were 1-2 ng/ml. During dehydration, there was a significant rise in plasma neurophysin I, together with an increase in neurophysin II. Haemorrhage also was associated with a rise in plasma neurophysin I and II, but the percent increase was greater for I than II. In two subjects in whom nicotine inhalation caused a rise in plasma neurophysin I, there was no detectable increase in plasma neurophysin II. These stimuli which have been reported to release vasopressin from the posterior pituitary also are associated with the differential release of neurophysin I. Plasma neurophysin II levels could more clearly be shown to rise independently of plasma neurophysin I during events thought to be related to oxytocin release. Plasma neurophysin II levels were significantly elevated in women taking oral contraceptives. Similarly during pregnancy there was a progressive rise in plasma neurophysin II concentration which was proportional to the period of gestation. Plasma neurophysin II concentrations in seven of fifteen nursing women rose significantly during suckling. There was no detectable change in plasma neurophysin I concentrations during any of these events. Plasma neurophysin I and II levels were both significantly elevated in fourteen patients with chronic renal failure and rose over haemodialysis, suggesting that the kidney may be the major route of clearance of the neurophysins. In humans the independent release of neurophysin II was associated with stimuli thought to release oxytocin, but neurophysin I showed only a differential release compared to neurophysin II in vasopressin stimulated events.

Neuroendocrine reactivity to nicotine in smokers

“…Positive, statistically significant Pearson correlations were found for integrated plasma vasopressin and neurophysin with plasma nicotine. These findings extend previous observations on AVP and its cartier protein NSN, in which nicotine dosage was estimated from cigarette content (Husain et al 1975;Dax et al 1979;Pullan et al 1979) and suggest that, when plasma nicotine is measured directly, a linear dose-response relationship emerges.…”

Increased Basal Plasma Vasopressin-Neurophysin in Mania

“…Basal blood samples (±10 ml) were taken by venipuncture in fasting, recumbent individuals at ± 8 a.m. as part of a larger neu roendocrine testing described previously [16,17], Since the original hNpI assay used previously [18] was no more available, we developed a personal hNpl assay. In summary, hNpl was purified according to a previously described method [19] fol lowed by a high-performance liquid chromatography step.…”

Estrogen-Stimulated Neurophysin in Chronic Renal Failure

“…It was reported that in patients undergoing hemodialysis, plasma A DH levels were significantly increased [6,15]. Elevation of plasma neuro physin in patients with CRF has also been observed [1,2,7,13]. However, this neurophysin was determined only by radioimmunoassay (RIA)and has not been charac terized immunologically or biochemically.…”