Differentiation between the effects of unprocessed portal blood and reduced liver function on brain indole amine metabolism in the portacaval shunted rat.

Changes in brain 5-HT turnover which have been associated with portal-systemic encephalopathy (PSE) in man were studied in rats with experimental PSE for intervals up to 15 weeks following the surgical construction of end-to-side portacaval shunts (PCS). These were compared to changes measured in portacaval transposed rats (PCT) which, show little hepatic dysfunction or cerebral abnormalities but, in common with the PCS rat, sustain total portal-systemic diversion. Thus any differences between these two groups were indicative of hepatic dysfunction and not the systemic diversion of portal blood. After 15 weeks, sustained increases were measured in brainstem and cerebral concentrations of the catabolite of 5-hydroxytryptamine (5-HT), 5-hydroxyindole acetic acid (5-HIAA), from 0.25+/-0.01 to 0.68+/-0.01*** microg g(-1) brain and from 0.18+/-0.01 to 0.31+/-0.03*** microg g(-1) brain respectively in PCS rats and were statistically greater to those measured in the brainstem and cerebrum of PCT and control rats. Sustained increases in cerebral concentrations alone of 5-hydroxytryptophan (5-HTP), the precursor of 5-HT, from 0.17+/-0.01 to 0.23+/-0.02 microg g(-1) brain were measured in PCS rats and were significantly*** greater than in PCT control rats after 15 weeks. Some early increases in 5-HTP were measured in PCS above control rats but these were not significant after 15 weeks. No sustained significant differences between the 3 groups were measured in 5-HT after 15 weeks. These data confirm previous evidence that the elevations in 5-HTP and 5-HIAA concentrations observed in experimental chronic liver failure and PSE are due to liver dysfunction and not portal-systemic diversion and may contribute additional information regarding the role of derangements in central 5-HT turnover as one of the causes of PSE. ***p<0.001, Newman-Keuls ANOVAR followed by Student's unpaired t-test for individual comparisons, (data shown are mean +/- SEM).

Localization and peptide content of endocrine pancreatic tumors.

Endocrine pancreatic tumors contain and frequently secret neurohormonal peptides. This phenomenon can be used as a diagnostic and classifying tool. This study analyzes 31 patients operated on because of an endocrine pancreatic tumor, including the diagnostic procedures and the localization methods. In 15 insulinoma cases only 6 patients had a positive arteriography, while all 11 selective pancreatic vein samplings were positive. The immunoreactivity showed that, besides insulin, most tumors also contained other peptides. Of four gastrinoma cases the arteriography was positive in three, but the selective vein sampling localized the tumor in all. The tumor's content of peptides showed mixed patterns. In the four glucagonomas, the arteriography was positive in all and the venous sampling performed in three of the cases also was positive. In five pancreatic polypeptide-containing tumors (PP-omas) the arteriography was positive in four and sampling performed in two was positive in both. In the PP-omas the peptide pattern showed that these tumors frequently contain several peptides. We used selective pancreatic vein sampling in 21 cases with positive result in all. In the cases in which arteriography was negative, the sampling results helped the surgeon to find the tumor. The peptide pattern in the tumors varied greatly and most tumors were multihormonal.

The effects of ammonia tolerance tests on the cerebrospinal fluid concentrations of amino acids and indoleamines in patients with liver cirrhosis.

To study the effect of ammonia administration on amino acids and indoleamines in cerebrospinal fluid (CSF) and on amino acids, insulin, and glucagon in plasma in humans with liver cirrhosis, we performed seven ammonia tolerance tests on six patients with stable liver cirrhosis. The grade of encephalopathy was determined by psychometric tests. Only one of the patients had pronounced encephalopathy. The other patients had no or only slight encephalopathy. The plasma concentrations of valine, leucine, isoleucine, phenylalanine, tyrosine, and methionine decreased after the ammonia load, whereas no changes were found in the plasma concentrations of glucagon and insulin. In CSF the concentrations of glutamine, aromatic amino acids, and indoleamines increased only in the patient who had pronounced encephalopathy, whereas no changes were found in the other patients. The effect of an ammonia load on the concentrations of neutral amino acids in CSF in patients with pronounced encephalopathy remains to be demonstrated.

Cooling enhances alpha 2-adrenoceptor-mediated vasoconstriction in human hand veins.

The contribution of different receptor subtypes in the contractile response during cooling in human hand vessels is of considerable interest in the understanding of cold-induced peripheral vasospasm as it appears in Raynaud's phenomenon. Subcutaneous vein segments from 50 patients undergoing hand operations not related to vascular disorders were examined in vitro. The temperature in the organ bath was initially 37 degrees C and was either continuously lowered to 10 degrees C or kept constant at 37 degrees C, 29 degrees C or 20 degrees C. The characteristics of the alpha-adrenoceptor-mediated motor response were elucidated with the use of the alpha 1-antagonist, prazosin, and the alpha 2-antagonist, yohimbine. A great variability between individuals in the proportions of alpha 1- and alpha 2-adrenoceptors was found. In the majority of the vessels continuous cooling to 25 degrees C augmented a noradrenaline-induced contraction. This augmentation was unaltered in the presence of prazosin but abolished by yohimbine, suggesting that it was mediated via the alpha 2-adrenoceptor. In the remaining vessels with a predominating alpha 1-adrenoceptor-mediated response a cold-induced relaxation was registered. This could be the result of a reduced alpha 1-adrenoceptor-mediated contraction at this low temperature. These varying reactions to cooling were unaffected by the beta-antagonist, propranolol, and by endothelial denudation. The results obtained in corresponding experiments with the alpha 1-agonist methoxamine and alpha 2-agonist, oxymetazoline, were conflicting, probably due to the poor selectivity of these agonists in human tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitonin, calcitonin gene-related peptide, and gastrin-releasing peptide in familial thyroid medullary carcinoma.

We examined immunocytochemically the occurrence of the three peptides calcitonin, calcitonin gene-related peptide (CGRP), and gastrin-releasing peptide (GRP) in medullary carcinoma of the thyroid. We also sought to determine whether the plasma levels of these peptides were increased when stimulated with calcium and pentagastrin in familial medullary carcinoma of the thyroid (MCT). The tumor tissue from all 17 cases examined was found to exhibit calcitonin and CGRP immunoreactivity, and in 15 of the 17 cases the tumor tissue also contained GRP immunoreactivity. In 7 of the cases selected at random, an intravenous injection of calcium carbonate (2 mg/kg body weight) and pentagastrin (0.6 microgram/kg body weight) produced marked elevation in plasma levels of calcitonin but did not significantly alter the plasma levels of CGRP or GRP. We conclude that most MCT tumors contain CGRP and GRP immunoreactive cells but that the plasma levels of CGRP and GRP are not altered on stimulation. This finding is clearly in contrast to the markedly elevated calcitonin levels. Hence, determination of plasma calcitonin levels still seems to be the most appropriate diagnostic test for MCT.

Serotonin receptors in the brain following total hepatectomy in rats treated with branched-chain amino acids.

Serotonin concentrations and receptor binding characteristics were investigated in rats subjected to total hepatectomy, portacaval shunt (PCS) or sham-operation. The animals were infused for 5 hr with a 10% glucose solution or the same solution enriched with 0.24 M branched-chain amino acids (BCAA). Hepatectomized animals were in grade-two coma at the end of the experiment independent of infusion. Indoleamines in mesencephalon-pons and diencephalon were analyzed by high-pressure liquid chromatography with electrochemical detection. Serotonin receptors (5-HT1 and 5-HT2) were investigated in the cortex and hippocampus by radioligand binding studies using 3H-serotonin for analysis of 5-HT1-receptors and 3H-ketanserin for analysis of 5-HT2-receptors. Concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were significantly increased after hepatectomy compared with controls. Treatment with BCAA significantly decreased 5-HT and 5-HIAA levels in hepatectomized animals. The affinity and the number of binding sites for the 5-HT1 and 5-HT2 receptors were found to be similar in all groups. The present study indicates that PCS for 1 week and the anhepatic state for 5 hr in rats do not influence brain serotonin receptors in contrast to previous studies in pigs with liver ischemia or rabbits with galactosamine-induced liver damage. In addition, infusion of BCAA for 5 hr did not alter the binding characteristics.

Repeated hepatic ischemia as a treatment for carcinoid liver metastases.

Hepatic ischemia has been used in the treatment of bilobar malignant carcinoid tumors in the liver. Hepatic artery ligation, hepatic dearterialization, and embolization with nondegradable micromaterial have been followed by collateral formation and are associated with a high complication rate. To reduce this, an implantable vascular occluder permitting intermittent occlusion of the hepatic artery was used in 3 patients with bilateral malignant carcinoid in the liver, with high urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA). Following a thorough dearterialization of the liver and division of all attachments, except for the hepatic artery, portal vein, and common duct, the vascular occluder was placed around the hepatic artery and connected to an implantable subcutaneous port. The hepatic artery was occluded by injecting a few milliliters of saline into the port and flow was released by withdrawal of the same amount of saline. Two patients had an anomalous blood supply to the right lobe and the arterial branch was transposed to the proper hepatic artery. One patient had the hepatic artery regularly occluded for 16 hours at 4-6 week intervals. Two patients managed to do the occlusions by themselves at home for 1 hour twice daily. Two patients had a normalization of the urinary excretion of 5-HIAA after 4 and 9 months. On follow-up with computed tomographic scanning, tumor regression was noted in one, however, there was no change in the other. The third patient has already had a 75% reduction of urinary excretion of 5-HIAA after 2 months of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of ammonia infusion on brain monoamine metabolism in portacaval-shunted rats.

The effect of ammonia infusion on monoamine metabolism was studied in the rat brain. Seven days after portocaval shunt (PCS) or sham operation animals were infused with ammonia or saline. Brain metabolism of serotonin and norepinephrine was studied after injection of a decarboxylase inhibitor (m-hydroxybenzylhydrazine, NSD 1015) which blocks the conversion of 5-hydroxytryptophan to serotonin and dihydroxyphenylalanine to dopamine. Neurologic testing was conducted before killing. Plasma and brain amino acids were measured. PCS animals infused with ammonia were in deep coma after 6 h infusion, whereas sham-operated animals were virtually unaffected. Brain amino acid analyses demonstrated increased concentrations of the aromatic amino acids and a tenfold increase in glutamine. Serotonin metabolism was diminished after 6 h. Dopamine synthesis was normal, but norepinephrine levels were low after 6h. The study suggests that hyperammonemia in PCS rats results in a depression of the serotonin synthesis rate in accordance with two previous studies but in contrast to previous hypotheses on the regulation of serotonin metabolism.

Evaluation of temporary liver dearterialization and embolization in patients with metastatic carcinoid tumour.

Patients with serotonin-containing metastatic midgut carcinoid tumours were treated with temporary liver dearterialization (19 patients) or liver embolization (8 patients). After 3, 6 and 12 months the effects of treatment were registered in changes in serotonin in platelet-poor plasma and blood, in urinary 5-HIAA, in tumour extent in the liver and in symptomatic relief. Seventeen patients, who underwent the dearterialization procedure survived the operation, while 2 patients who had a concomitant small bowel resection died of complications. Tumour response was obtained in 8 patients after 6 months and in 9 patients after 12. Stable disease was noted in 5 patients after 6 months and 3 patients after 12 months. Progressive disease was seen in 4 patients. All 19 patients except one exhibited the carcinoid syndrome prior to operation and 11 patients were free from symptoms for at least 12 months postoperatively. The gelatine foam powder liver embolization was performed uneventfully in all 8 patients. Tumour response was obtained in 3 patients at both 3 and 12 months. Stable disease was noted in 5 patients at 3 months and 4 patients at 12 months. Before embolization the patients suffered from the carcinoid syndrome and the treatment resulted in the immediate disappearance of the syndrome in 5 patients. After 12 months one patient was still free from obvious carcinoid symptoms. In one patient the disease aggravated in spite of treatment and he died 5 months after embolization. Thus, temporary liver dearterialization and liver embolization in midgut carcinoid patients resulted in tumour regression and symptomatic relief in 9 out of 19 patients and 3 out of 8 patients respectively. The complication rate was low.

Interferon treatment in patients with malignant carcinoids.

Thirteen patients with ileal carcinoids complicated by liver metastases were treated with human leukocyte interferon (IFN) subcutaneously (s.c.) at doses of 3-6 x 10(6) IU/day 5 days weekly during 12 months. Objective tumour response was obtained in 2 patients, based on reduction in tumour size in one patient and on reduction in tumour markers in the other. Stable disease was noted during the 12-month treatment period in 10 patients. Progressive disease was seen in one patient. This patient exhibited tumour growth, new metastases and increases in tumour markers. Among patients with daily flushing prior to treatment, 50% were free of flush after 12 months of IFN. Adverse effects, including a mild influenza-like syndrome, joint and muscle pains, tiredness and reduction of blood cells were observed but did not necessitate long-term dose reductions. Thus, IFN therapy to midgut carcinoid patients resulted in tumour response or stable disease in 12 out of 13 patients without causing severe side effects.

Brain 5-HT1 and 5-HT2 binding sites following portacaval shunt in the rat.

Brain serotonin 5-HT1 and 5-HT2 binding properties were investigated in experimental chronic portal-systemic encephalopathy (PSE). End-to-side portacaval shunted (PCS) rats were subjected to open field behavioral testing (spontaneous activity and exploration) 3 weeks after the shunt procedure. Each individual animal was then assayed for 5-HT1 and 5-HT2 binding properties (Bmax and KD) in the cortex + hippocampus by the use of radioligand binding and rapid filtration technique. (3H)serotonin was used to label 5-HT1 binding sites and (3H)ketanserin to label 5-HT2 binding sites. Results revealed that the PCS rats exhibited significant behavioral changes with decreased spontaneous activity and exploratory behavior as compared with sham-operated controls (sham). The affinity for, and the number of, 5-HT1 and 5-HT2 binding sites, respectively, were not different between PCS and sham rats. The brain 5-HT1 and 5-HT2 binding properties were within the range of Bmax and KD previously reported for normal rats when similar techniques are used. This first report in PCS rats on the subject of brain 5-HT1 and 5-HT2 binding properties demonstrates that no major alterations are likely to occur. This contrasts the knowledge of a markedly increased brain serotonin synthesis rate in the PCS rat, suggesting minor functional relevance of the perturbed brain serotonin metabolism associated with chronic PSE.

Serotonin metabolism in the central nervous system in portacaval shunted rats infused with fat emulsion.

Increased brain concentrations of tryptophan, and presumably thereby increased brain serotonin metabolism, have been observed following liver impairment and implicated in the etiology of portal-systemic encephalopathy (PSE). Increased plasma-free tryptophan (ie, not albumin-bound) concentrations can be expected after exogenous fat administration. This might further increase the brain serotonin metabolism in liver failure and negatively influence the PSE. We treated rats 2 weeks after end-to-side portacaval shunt (PCS) with continuous intravenous infusion of fat emulsion (Intralipid 20%) for 24 and 72 hr, respectively. The regional serotonin turnover was determined in different regions of the central nervous system (CNS) by measuring 5-hydroxyindole concentrations after NSD 1015 decarboxylase inhibition. The results revealed no further increase of the CNS serotonin turnover after fat infusion to PCS rats, compared with PCS rats given equal amounts of glucose. Thus, continuous infusion of a fat emulsion caused no major alteration of the CNS serotonin metabolism in PCS rats.

The impact of time after portacaval shunt in the rat on behavior, brain serotonin, and brain and muscle histology.

We investigated open field behavior, cellular fluorescence of brain serotonin and serotonin metabolism in different regions of the central nervous system (CNS), and brain and muscle histology in rats 3 weeks or 6 months after surgical end-to-side portacaval shunt (PCS). The results revealed a similar disturbance of the CNS serotonin at 3 weeks and 6 months after PCS in the rat. Progressive neurohistological changes were present between 3 weeks and 6 months after PCS. The open field behavioral impairment appeared, however, to diminish with time. There was no evidence from muscle biopsies that lesions in the muscles or in the peripheral nerves contributed to the motor disturbance.

Cholecystokinin (CCK)-4 and CCK-8 stimulate islet hormone secretion in vivo in the pig.

It is known that cholecystokinin (CCK) stimulates islet hormone secretion under a variety of experimental conditions. Since CCK occurs in several different molecular forms, with 58, 39, 33, 12, 8, or 4 amino acid residues, the question has evolved as to which is the shortest active form of CCK. We therefore investigated the influences of the C-terminal octapeptide of CCK, CCK-8 (sulfated form) and of the C-terminal tetrapeptide, CCK-4, on the secretion of insulin, glucagon, and somatostatin from the pig pancreas in vivo by infusing each of the two peptides into the superior pancreatic artery. We found that islet hormone secretion increased promptly upon infusion of both CCK-8 and CCK-4. Thus, the secretion of insulin was stimulated from 51 +/- 12 to 295 +/- 70 microU/min during the first 2 min after injection of CCK-8 and from 40 +/- 12 to 240 +/- 78 microU/min after injection of CCK-4. Similarly, the secretion of glucagon was stimulated from 240 +/- 45 to 357 +/- 38 pg/min after CCK-8 and from 282 +/- 44 to 335 +/- 43 pg/min after CCK-4, and somatostatin secretion was stimulated from 112 +/- 7 to 226 +/- 12 pg/min by CCK-8 and from 105 +/- 11 to 246 +/- 16 pg/min by CCK-4. With regard to the efficiency to stimulate the secretion of these three islet hormones, CCK-8 and CCK-4 were equipotent. We conclude that in pigs, CCK-8 and CCK-4 both stimulate the secretion of insulin, glucagon, and somatostatin from the pancreas in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Serotonin metabolism in the central nervous system following sepsis or portacaval shunt in the rat.

Similar neurological disturbances and metabolic alterations have been observed in liver insufficiency and in bacterial sepsis. In both liver failure and sepsis an altered neurotransmitter profile in the central nervous system (CNS) has been implicated in the pathogenesis of encephalopathic symptoms. It has been suggested that equivalent disturbances in brain neurotransmitters, especially serotonin, play a role in the encephalopathy accompanying sepsis and liver failure. The objective of this study was to compare the CNS serotonin metabolism in rats with an end-to-side portacaval shunt (PCS) with that found in rats with 12 or 24 hr of intraabdominal sepsis. The metabolism of CNS serotonin was estimated after inhibition of two enzymes acting in the 5-hydroxyindole synthetic pathway (decarboxylase and monoamine oxidase). The 5-hydroxyindoleacetic acid (5-HIAA) concentrations were determined in different regions of the CNS, thereby permitting evaluation of the synthetic activity of the serotonin neurotransmitter system. As previously reported, a marked increase in CNS serotonin synthetic rate was noted following PCS. In contrast, and in contradistinction to several recent reports, no major changes in the CNS serotonin synthesis rate were present following 12 or 24 hr of sepsis. CNS levels of the serotonin metabolite 5-HIAA were elevated in both sepsis and PCS rats. These data indicate that sepsis and liver failure have different effects upon serotonin metabolism in the CNS and suggest that differing pathogenetic mechanisms may underlie the encephalopathy clinically associated with these conditions.