The radioimmunoassay of neurophysins as a tool for the posterior pituitary investigation

AVP- and OT-neurophysins response to apomorphine and clonidine in major depression

A number of studies have reported abnormalities of neurohypophyseal secretions in major depressive disorder. The purpose of the present study was to test the influence of apomorphine and clonidine injections on plasma vasopressin (AVP)-neurophysins and oxytocin(OT)-neurophysins levels, as direct index of posterior pituitary activation in major depression. Apomorphine and clonidine tests were carried out in 25 medication-free depressive patients and 25 age and gender-matched healthy controls. Blood for neurophysins analysis was drawn by venipuncture at t0, t + 20, t + 40, t + 60 and t + 120. Baseline AVP-neurophysins concentrations were significantly lower in depressives (0.12 +/- 0.14 ng/ml) than in healthy subjects (0.24 +/- 2.15 ng/ml) (p < 0.04). The response to apomorphine test revealed a significant reduced response at 20 (p = 0.01), 40 (p = 0.007) and 60 (p = 0.02) and 120 (p = 0.02)min. Following clonidine test, post hoc tests also revealed a significant decrease at 0 (p = 0.04), 20 (p = 0.01), 40 (p = 0.007) and 60 (p = 0.02) and 120 (p = 0.006)min. Concerning OT-neurophysins, no significant differences were found between depressed and controls in response to clonidine or apomorphine injections. Following clonidine and apomorphine, major depressives exhibited a significantly lower peak GH response than controls. The study supports partially the hypothesis of a reduced vasopressinergic activity in depression. Moreover, we did not find any influence of acute apomorphine or clonidine injections on vasopressin-neurophysin or oxytocin-neurophysin in depressive patients.

Plasmatic vasopressin neurophysin in depression: basic levels and relations with HPA axis

A decreased secretion of arginine vasopressin (AVP) has been implicated in depression. In order to further investigate this hypothesis, we studied the plasma level of the specific peptidergic carrier of AVP, vasopressin neurophysin (hNpI), in 26 depressed inpatients and 16 matched normal controls. On the other hand, AVP has also been involved in the pathophysiology of the cortisol postdexamethasone nonsuppression frequently observed in depression. Therefore, we investigated concomitantly hNpI and cortisol during a dexamethasone (DXM) suppression test. hNpI and cortisol were assessed by radioimmunoassay at 8 AM and 8 PM during 4 consecutive days. From days 2 to 3, 4 mg (DXM) was given orally. hNpI values were not affected by DXM administration. Compared with controls, patients showed higher pre- and post-DXM cortisol values and lower hNpI values. No difference in hNpI values was observed between DXM escapers or nonescapers. Our results are consistent with an impaired AVP secretion in depression and fail to support a role of AVP in the early cortisol escape.

Changes in total serum immunoreactive neurophysins and corticosterone levels after restraint stress in rats

This study indicates that total immunoreactive circulating neurophysins (IRN) increased in male rats submitted to acute restraint stress. Total immunoreactive serum corticosterone levels also were elevated, confirming the stressful character of the restraint situation. It is speculatively suggested that IRN elevations due to stress are the reflection of a corticotropin releasing factor (CRF)-IRN product.

Peripheral neurophysins changes under mild stress conditions

Total immunoreactive neurophysins levels increased significantly in rats after they had been trained in a situation based on the innate light-dark avoidance principle. These levels varied according to the amount of 'familiarisation cues' which characterised the situation. The results are discussed in terms of arousal/stress-neurophysins relationships.

Temporal relationship between plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F and neurophysin I/II around luteolysis in sheep

Plasma concentrations of neurophysin I/II (N-I/II), 13,14-dihydro-15-keto-prostaglandin F (PGFM) and progesterone were measured by radioimmunoassay in plasma samples collected from four sheep at hourly intervals between 0700 and 1900 h from Days 12-17 of the estrous cycle. Plasma samples were also collected from a fifth sheep at 2-hourly intervals during Days 12-16 of the cycle. In all sheep, intermittent surges in the plasma concentrations of PGFM and N-I/II occurred during the period of luteal regression. On at least one occasion in each sheep a surge in the plasma concentration of N-I/II was observed coincident with a rise in PGFM concentrations. In general, the highest levels of N-I/II were observed early in luteolysis (Days 13-14 of the cycle) while the corresponding levels of PGFM in plasma were maximal around Day 15 when luteolysis was well advanced. It is suggested from this temporal data that oxytocin, which is considered to be released in association with N-I/II, may play an important role in ovine luteolysis by stimulating the secretion of prostaglandin F from the uterus during days 13-15 of the estrous cycle.