Naloxone increases the release of oxytocin, but not vasopressin, within limbic brain areas of conscious parturient rats: a push-pull perfusion study

The influence of naloxone on the release in limbic brain areas of both oxytocin (OXT) and vasopressin, measured by radioimmunoassay, was studied in conscious parturient rats. Three consecutive 30-min push-pull perfusions (20 microliters artificial CSF/min) were made, via previously implanted guide cannulae, within the medio-lateral septum and dorsal hippocampus of parturient animals given saline or naloxone hydrochloride (5 mg/kg body weight) after delivery of the second pup. OXT release in the hippocampus, but not in the septum, was increased during parturition, compared to day 1 post partum. During the first 30-min collection period following naloxone administration, release of OXT was significantly elevated within the septum (44% compared to saline controls, p less than 0.002), but not in the dorsal hippocampus; vasopressin release was not affected. In contrast, on day 1 post partum, naloxone, administered 5 min after starting two consecutive perfusions failed to alter OXT release in septum or hippocampus in conscious rats. Naloxone, known to increase the release of OXT also from the posterior pituitary during parturition, speeded the parturition process significantly between the birth of pups 4 and 8 during push-pull perfusion of septum or hippocampus. The data suggest that endogenous opioid inhibition is involved in the regulation of central OXT release, but not vasopressin release, during parturition. Together with previous studies on OXT release from the posterior pituitary, it seems that during parturition there is coordinated endogenous opioid action on the release of OXT both into blood and into the brain.

[The effect of combination epidural anesthesia techniques in upper abdominal surgery on the stress reaction, pain control and respiratory mechanics]

Twenty-eight patients undergoing upper abdominal operations (mainly selective proximal vagotomy [SPV]) were referred for assessment of the hormonal metabolic reaction (adrenocorticotropic hormone [ACTH], arginine vasopressin [AVP], cortisol, and glucose), the postoperative pain reaction, and respiration according to the method of anesthesia (group 1: neuroleptanesthesia [NLA], group 2: NLA in combination with epidural opiate analgesia, group 3: NLA in combination with local anesthesia). To alleviate postoperative pain piritramide was systematically administered in group 1, whereas in groups 2 and 3 a thoracic epidural catheter was injected with morphine or bupivacaine. Postoperative analgesia was better in patients with epidural administration than in those with systemic application. On the 1st and 2nd postoperative days the vital capacity was statistically significantly higher by 10%-15% in groups 2 and 3 than in group 1. As expected, the neurohormonal and metabolic stress response was highest in all patients in the intraoperative and immediate postoperative phases: ACTH, AVP, and glucose levels were in most cases significantly higher compared with the initial values. However, cortisol levels decreased intraoperatively, probably as a result of the generally used induction agent etomidate. Comparison of the three methods of anesthesia revealed that all mean hormone levels analyzed in group 2 patients were lower both intraoperatively and 2 h postoperatively, which implies that epidurally administered morphine reduces the stress reaction, probably indirectly through additional selective alleviation of pain at the spinal cord level. The various differences in hormonal reactions of patients in groups 1 and 3 gave no clear evidence, however, of possible mitigation of the stress reaction by epidural local anesthetics in upper abdominal operations.

Septal and hippocampal release of vasopressin and oxytocin during late pregnancy and parturition in the rat

The push-pull perfusion technique, in conjunction with specific radioimmunoassays, was used to monitor the release of both arginine vasopressin (AVP) and oxytocin (OXT) within distinct limbic brain areas of conscious female rats. In pregnant rats near term, the release of AVP was greater than that of virgin rats in both the ventral (p less than 0.001) and mediolateral (p less than 0.001) septal areas; similarly, release of OXT increased in the ventral septal area (p less than 0.01) at this time. In contrast, no changes in the levels of either peptide occurred in the dorsal hippocampus. In parturient rats, AVP release tended to decrease in the septal areas but increased fivefold in the dorsal hippocampus (p less than 0.001) compared to pregnant animals. In contrast, OXT levels assayed in the same perfusates did not differ from those observed in pregnant animals. Plasma levels of AVP in pregnant rats (p less than 0.05) and of OXT in parturient animals (p less than 0.01) were found to be increased over levels in virgin rats. The regionally different and peptide-specific changes in release pattern of AVP and OXT in virgin, pregnant and parturient rats may be of physiological significance in antipyresis and behaviors accompanying parturition.

Vasopressin release within the supraoptic and paraventricular nuclei of the rat brain: osmotic stimulation via microdialysis

The combination of microdialysis and a highly sensitive radioimmunoassay was used in order to monitor the in vivo release of arginine vasopressin (AVP) within hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei of the rat brain. A dialysis probe was inserted into the SON or PVN area and microdialysis was performed in conscious or urethane-anesthetized animals before, during and after hypertonic artificial cerebrospinal fluid (aCSF, with 1 M NaCl) was delivered via the probe. The recovery of AVP in vitro was 1.60%, that of [3H]OH in vitro 14.2% and in vivo 8.44% (SON) and 9.26% (PVN), respectively. AVP was consistently detected in both SON and PVN dialysates; basal levels averaged 0.87 +/- 0.22 pg/30-min dialysate (SON, n = 51) and 0.80 +/- 0.24 pg/30-min dialysate (PVN, n = 6), respectively. Hypertonic aCSF given over a period of 30 min, 60 min or 90 min, resulted in an increased AVP release within the SON which, however, reached its peak (to 8.86-10.27 pg/sample; P less than 0.001 as compared to basal) only in the poststimulation period, i.e. after replacement of hypertonic with isotonic aCSF. An identical osmotic stimulus given 150-210 min after the first one produced similar, though slightly declined, changes in AVP release. In the PVN, AVP release patterns prior to and in response to the first hypertonic pulse were similar to those in the SON; a possible functional difference between the two nuclei is indicated by the lack of a rebound increase in AVP release following the second stimulation. The physiological significance of intranuclearly released AVP remains to be shown.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term results in pancreatic transplantation with special emphasis on the use of prolamine

Our pancreatic transplantation programme was initiated in 1979. Since then a total of 102 pancreas transplantations have been performed, blocking exocrine secretion using the duct occlusion technique with prolamine. Early non-immunological complications are frequent. The long-term results (9 years) in combined pancreas and kidney transplanted patients are satisfying: the survival rate for pancreas is 38% and 54% for kidney. Patient survival rate in this period is 85%. Beyond the first year post-transplant the exocrine activity disappears whereas the endocrine function remains well preserved.

Follow-up study of sensory-motor polyneuropathy in type 1 (insulin-dependent) diabetic subjects after simultaneous pancreas and kidney transplantation and after graft rejection

The influence of successful simultaneous pancreas and kidney transplantation on peripheral polyneuropathy was investigated in 53 patients for a mean observation period of 40.3 months. Seventeen patients were followed-up for more than 3 years. Symptoms and signs were assessed every 6 months using a standard questionnaire, neurological examination and measurement of sensory and motor nerve conduction velocities. While symptoms of polyneuropathy improved (pain, paraesthesia, cramps, restless-legs) and nerve conduction velocity increased, there was no change of clinical signs (sensation, muscle-force, tendon-reflexes). Following kidney-graft-rejection there was a slight decrease of nerve conduction velocity during the first year, which was not statistically significant. Following pancreas-graft rejection there was no change of nerve conduction velocity during the first year. Comparing the maximum nerve conduction velocity of the patients with pancreas-graft-rejection to the nerve conduction velocities of these patients at the end of the study, there was a statistically significant decrease of 6.5 m/s. In conclusion, we believe that strict normalization of glucose metabolism alters the progressive course of diabetic polyneuropathy. It may be stabilized or partly reversed after successful grafting even in long-term diabetic patients.

Diabetic retinopathy and pancreas transplantation: a 3-year follow-up

The effect of simultaneous pancreas and kidney transplantation on diabetic retinopathy was studied in a prospective study with 30 patients (57 eyes) and 15 control subjects (26 eyes), patients who lost the pancreas, but preserved kidney function. There was no significant difference between the groups after a mean observation time of more than 35 months (a range of 12 to 96 months). Both populations had a stable retinopathy during follow-up. This seems to be a consequence of the far advanced retinopathy (mean duration of type 1 diabetes was 22 years) and the high percentage of coagulated eyes (81% and 85%, respectively), but is not related to the organ transplantation. A closer look at the few patients who did not receive laser coagulation (14 patient and 6 control eyes), produced a different result. Four control eyes experienced a significant deterioration of the retinopathy which had been stable before rejection. It is the most important and so far never mentioned aspect of this study, that periods of destabilisation are a definite threat for the retinopathy. Nevertheless, it seems questionable whether we will ever be able to make a definite statement on the pancreas-eye relation, as long as the transplantation must be restricted to carefully selected late-stage diabetic subjects.

Diabetic microangiopathy in type 1 (insulin-dependent) diabetic patients after successful pancreatic and kidney or solitary kidney transplantation

To evaluate the beneficial effect of pancreatic grafting on peripheral microcirculation and long-term clinical outcome, we compared data of 28 Type 1 (insulin-dependent) diabetic patients either given a pancreatic and kidney graft simultaneously or given a solitary kidney graft (n = 17). Peripheral microcirculation was estimated by transcutaneous oxygen pressure measurement (including reoxygenation potential after blood flow occlusion) and erythrocyte flow/velocity by a non-contact laser speckle method. All the measured parameters showed significant differences between diabetic and control subjects in the mean follow-up time of 49 (simultaneous pancreas and kidney transplantation) and 43 (solitary kidney transplantation) months. The data from patients after simultaneous pancreas and kidney transplantation revealed an improvement of transcutaneous oxygen pressure measurement (rise from 46 +/- 2 mm Hg to 63 +/- 3 mmHg), reoxygenation time (fall from 224 +/- 12s to 114 +/- 6s) and laser speckle measurement (rise from 4.2 +/- 1.7 to 5.6 +/- 1.8 relative units). The control group with solitary kidney transplantation did not show a positive evaluation. Data from patients after simultaneous pancreas and kidney transplantation revealed an improvement in transcutaneous oxygen pressure measurement, reoxygenation time and laser speckle measurement whereas the control group with solitary kidney transplantation did not show a positive evaluation. Improved microcirculation was more pronounced in patients with better microvascular preconditions. The results confirm that diabetic microangiopathy is positively influenced by pancreatic transplantation.

Quality of life in type 1 (insulin-dependent) diabetic patients prior to and after pancreas and kidney transplantation in relation to organ function

Improvement of the quality of life in Type 1 (insulin-dependent) diabetic patients with severe late complications is one of the main goals of pancreas and/or kidney grafting. To assess the influences of these treatment modalities on the different aspects of the quality of life a cross-sectional study in 157 patients was conducted. They were categorized into patients pretransplant without dialysis (n = 29; Group A), pretransplant under dialysis (n = 44; Group B), posttransplant with pancreas and kidney functioning (n = 31; Group C), post-transplant with functioning kidney, but insulin therapy (n = 29; Group D), post-transplant under dialysis and insulin therapy again (n = 15; Group E) and patients after single pancreas transplantation and rejection, with good renal function, but insulin therapy (n = 9; Group F). All patients answered a mailed, self-administered questionnaire (217 questions) consisting of a broad spectrum of rehabilitation criteria. The results indicate a better quality of life in Groups C and D as compared to the other groups. In general the scores are highest in C, but without any significant difference to D. Impressive significant differences between C or D and the other groups were found especially in their satisfaction with physical capacity, leisure-time activities or the overall quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of pancreatic and/or renal transplantation on diabetic autonomic neuropathy

Thirty-nine Type 1 (insulin-dependent) diabetic patients were studied prospectively after simultaneous pancreas and kidney (n = 26) and kidney grafting alone (n = 13) by measuring heart rate variation during various maneuvers and answering a standardized questionnaire every 6 to 12 months post-transplant. While age, duration of diabetes, and serum creatinine (168.1 +/- 35.4 vs 132.7 +/- 17.7 mumol/l) were comparable, haemoglobin A1 levels were significantly lower (6.6 +/- 0.2 vs 8.5 +/- 0.3%; p less than 0.01) and the mean observation time longer (35 +/- 2 vs 25 +/- 3 months; p less than 0.05) in the pancreas recipients when compared with kidney transplanted patients. Heart rate variation during deep breathing, lying/standing and Valsalva manoeuver were very similar in both groups initially and did not improve during follow-up. However, there was a significant reduction in heart rate in the pancreas recipient group. Autonomic symptoms of the gastrointestinal and thermoregulatory system improved more in the pancreas grafted subjects, while hypoglycaemia unawareness deteriorated in the kidney recipients. This study suggests that long-term normoglycaemia by successful pancreatic grafting is able to halt the progression of autonomic dysfunction.

Metabolic and hormonal studies of type 1 (insulin-dependent) diabetic patients after successful pancreas and kidney transplantation

Long-term normalization of glucose metabolism is necessary to prevent or ameliorate diabetic complications. Although pancreatic grafting is able to restore normal blood glucose and glycated haemoglobin, the degree of normalization of the deranged diabetic metabolism after pancreas transplantation is still questionable. Consequently glucose, insulin, C-peptide, glucagon, and pancreatic polypeptide responses to oral glucose and i.v. arginine were measured in 36 Type 1 (insulin-dependent) diabetic recipients of pancreas and kidney allografts and compared to ten healthy control subjects. Despite normal HbA1 (7.2 +/- 0.2%; normal less than 8%) glucose disposal was normal only in 44% and impaired in 56% of the graft recipients. Normalization of glucose tolerance was achieved at the expense of hyperinsulinaemia in 52% of the subjects. C-peptide and glucagon were normal, while pancreatic polypeptide was significantly higher in the graft recipients. Intravenous glucose tolerance (n = 21) was normal in 67% and borderline in 23%. Biphasic insulin release was seen in patients with normal glucose tolerance. Glucose tolerance did not deteriorate up to 7 years post-transplant. In addition, stress hormone release (cortisol, growth hormone, prolactin, glucagon, catecholamines) to insulin-induced hypoglycaemia was examined in 20 graft recipients and compared to eight healthy subjects. Reduced blood glucose decline indicates insulin resistance, but glucose recovery was normal, despite markedly reduced catecholamine and glucagon release. These data demonstrate the effectiveness of pancreatic grafting in normalizing glucose metabolism, although hyperinsulinaemia and deranged counterregulatory hormone response are observed frequently.

Outcome of renal grafts after simultaneous kidney/pancreas transplantation

Nineteen patients with endstage renal failure due to Type 1 (insulin-dependent) diabetes mellitus received simultaneous pancreas/kidney transplants using bladder drainage technique. Another group of 25 Type 1 diabetic patients received pancreas/kidney transplants by the duct occlusion technique. We observed a higher incidence of rejection episodes in the patients of the bladder drainage group than those in the duct occlusion group, 14 of 19 patients (74%) vs 7 of 25 (28%) respectively. Anti CD3 antibodies (OrthocloneR, OKT3) as a part of induction treatment was used more often in the bladder drainage group (58%) than in the control group (20%).

Long-term follow-up of diabetic retinopathy for up to 71 months after combined renal and pancreatic transplantation

This study reports the course of diabetic retinopathy in 25 patients (41 eyes, 9 one-eyed patients) who had undergone successful renal and pancreatic transplantation. The mean duration of follow-up was 38 months (range, 15-71 months). Visual acuity improved in 13 eyes (32%), remained stable in 19 (46%) and deteriorated in 9 (22%); only 2 of the latter 9 eyes (5%) sustained severe visual loss according to the definition of the Diabetic Retinopathy Study Group. The frequency and severity of vitreous hemorrhage improved in 19 eyes (46%), remained unchanged in 18 (44%) and worsened in 4 (10%). In comparison with other modes of treatment such as intensified conventional insulin therapy and artificial insulin-delivery systems, the combined renal and pancreatic transplantation seems to have advantages concerning the course of proliferative diabetic retinopathy.

The positive feedback action of vasopressin on its own release from rat septal tissue in vitro is receptor-mediated

The effect of arginine vasopressin (AVP) on its own septal release was evaluated using an in vitro superfusion procedure. As compared to basal release from septal fragments, pulses of synthetic AVP (15 pg/5 min) resulted in a 25-fold augmented release of endogenous AVP, indicating a positive feedback action. Both the basal and stimulated AVP release were significantly increased by 60 mM potassium and markedly reduced by omission of calcium. Preincubation of the septal fragments with the V2/V1 AVP receptor antagonist d(CH2)5 [D-Tyr (Et)2,Val4]AVP resulted in a dose-dependent inhibition of the positive feedback action of AVP which was nearly completely blocked at doses between 1.25 and 5 ng per 100 microliters incubation medium. As compared to this effect, the V1 antagonist d(CH2)5 Tyr (Me)2 AVP as well as oxytocin were significantly less potent. The results suggest that the positive feedback action of AVP on its own release from septal fragments is potassium-stimulated, calcium-dependent and mainly V2 receptor-mediated. The physiological significance of this phenomenon remains to be shown.

Plasmatic factors of haemostasis remain essentially unchanged except for PAI activity during n-3 fatty acid intake in type I diabetes mellitus

Diabetic patients are prone to develop vascular complications. Increased procoagulatory factors and a reduced fibrinolytic potential are considered as thrombogenic risk factors, although controversy remains. In epidemiological and dietary intervention studies fish or fish oil, rich in the two n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have demonstrated a potential to reduce cardiovascular disease. We compared the plasmatic coagulatory and fibrinolytic profile of 13 near normoglycaemic type I diabetics almost free of cardiovascular disease with healthy volunteers, matched for age and sex. Except for fibrinogen levels and tPA activity being elevated and soluble fibrin and fibrinopeptide A being reduced, no differences could be discerned between type I diabetics and controls in all investigated plasmatic parameters. In a dietary intervention study we investigated the effects of 5.4 g EPA and 2.7 g DHA per day during and after a 4-week dietary supplementation in the diabetic patients. The factors, inhibitors and activation products of coagulation and fibrinolysis measured were at best transiently affected by the diet. Only plasminogen activator inhibitory activity in plasma significantly increased during the dietary supplementation and returned to prediet values after cessation of n-3 fatty acids. Changes in PAI activity were negatively correlated to changes in serum triglycerides. We conclude that well adjusted type I diabetics show an almost unchanged haemostatic profile compared to matched healthy controls. A dietary intervention with n-3 fatty acids in these patients does not affect the plasmatic haemostatic pattern except for an increase in PAI activity.

Vasopressin receptors in the brain, liver and kidney of rats following osmotic stimulation

The binding site concentration (Bmax) and equilibrium dissociation constant (Kd) for [3H]-arginine vasopressin (AVP) binding sites were measured in limbic brain areas (septum, dorsal hippocampus, amygdala) and liver and kidney of control and osmotically stimulated male Wistar rats. Membrane binding was performed in these five areas 30, 60 and 180 min following intraperitoneal injection of hypertonic saline. This paradigm resulted in no significant change in binding characteristics in the septum, dorsal hippocampus, amygdala and liver from control treated rats. In contrast, the kidney Bmax was significantly reduced 60 min following osmotic stimulation, with no effect on affinity. These results also suggest that AVP receptors in the CNS are relatively resistant to regulatory effects of an acute AVP exposure.

[Pancreas transplantation in Type I diabetic patients]

Successful pancreas transplantation can result in the longterm normalization of glucose metabolism. Since most pancreas recipients already have severe diabetic complications, and the observation period after transplantation is rather short, an assessment of the effect of complete glucose normalization on these diabetic changes is problematic. It has, however, been shown that the development of diabetic nephropathy can be prevented, peripheral microcirculation improved, and autonomic and peripheral neuropathy and retinopathy stabilized. These positive effects are, possibly, in part due to the elimination of uremia, since most patients receive both a pancreas and a kidney. The aim must be to perform pancreas transplantation in an early stage of diabetes, even though remarkable improvements have also been reported in terminal stages of the disease, and the quality of life of these patients has been significantly improved.

[Significance and diagnosis of autonomic neuropathy in diabetes]

The results of studies performed to date would appear to show that autonomic neuropathy (ANP) in diabetics can involve any organ system. The earliest and most common manifestation is seen in the cardiovascular system, and finds expression as orthostatic phenomena, resting tachycardia, and "rigid pulse". Simple, non-invasive tests permit accurate quantification and follow-up. ANP in the gastrointestinal tract manifests as a motility disturbance, and the resulting delay in absorption might be the cause of inexplicable blood sugar fluctuations. A phenomenon of decisive importance for the diabetic is the lowering of his awareness of a hypoglycemic state. For this reason, intensive training of the diabetic in the self-determination of blood sugar and requirement-matched insulin dosage are thus of extreme importance. Disturbances of sexual function, which are all too rarely mentioned, usually put a heavy strain on the diabetic. Medical care of diabetics prior to, during and after surgery should give due consideration to cardiac, pulmonary and gastrointestinal ANP involvement. In view of the limited therapeutic possibilities, prevention of ANP should receive top priority.

Vasopressin and oxytocin in rat brain in response to prostaglandin fever

Urethan-anesthetized rats were used to identify effective stimuli for the release of the peptides arginine vasopressin (AVP) and oxytocin into the ventral septal area (VSA) of the brain. Febrile responses to intracerebroventricular injection of prostaglandin E1 (PGE1) were observed in rats whose body temperatures were maintained at 35, 37, or 39 degrees C. Microinjection of the AVP antagonist d(CH2)5Tyr(Me)AVP into the VSA enhanced fever only when PGE1 administration was associated with a significant rise in body temperature. Passive elevation ("artificial fever") or reduction of body temperature in the absence of a PGE1 stimulus was not affected by the antagonist. Push-pull perfusion of the VSA and the dorsal hippocampus, followed by radioimmunoassay of perfusates for AVP and oxytocin, revealed enhanced release into the VSA of AVP only when PGE1 administration was followed by a rise in body temperature. Oxytocin was released whenever body temperature was raised. Peptide concentrations in simultaneous perfusates of dorsal hippocampus did not change in response to PGE1 administration or to passive elevation of body temperature. We conclude that AVP is released into the VSA, but not the dorsal hippocampus, of the rat during a fever induced by PGE1. Oxytocin is released into the VSA, but not the hippocampus, when temperature is elevated.