Compliance with an oral hyperproteic supplement with fibre in nursing home residents

BACKGROUND

Undernutrition is a common problem in older individuals that may be related to a low protein dietary intake. Oral supplements may improve the health status in this population, but their use may be limited by compliance and side effects.

OBJECTIVES

To evaluate effects of an oral supplement of protein and fibre on compliance, on nutritional status, and on intestinal habits in nursing home residents.

METHOD

A prospective observational study was carried out in 66 Spanish nursing homes. 358 subjects undernourished or at risk of undernutrition requiring nutritional supplements. After informed consent was given, subjects received 2 daily cartons (400 ml) of a liquid oral supplement rich in protein and fibre along 3 months. Supplement intake compliance was measured at baseline and after 6 and 12 weeks. Nutritional status was assessed using the Mini- Nutritional Assessment (MNA), weight, and Body Mass Index (BMI). Changes in intestinal habits and digestive symptoms were also recorded, as well as subject's supplement acceptance.

RESULTS

Compliance with the supplement intake was 97.46% at 6 weeks and 96% at 12 weeks of follow-up. Significant changes (p<0.0001) were found in nutritional status: mean value of MNA improved from baseline (MNA=14.0+/-3.9) after 12 weeks (MNA=17.0+/-4.0), as well as weight (+2.1 kg, a 4.1% increase). The BMI did not change significantly (BMI=21.43 at baseline; BMI=21.78 at 12 weeks). Undernutrition prevalence (MNA<17) decreased from 76.4 to 46.6% (p<0.0001). Intestinal habits showed a significant improvement in defecation frequency (from 4.7 to 6.1 stools per week, p<0.0001) and faeces consistency (from 53.2% to 74.5% reporting formed soft stools, p<0.0001). 48.9% of the subjects considered to have better intestinal habits after 6 weeks and 50.5% after 3 months of supplementary food intake, the rest reporting no change. Vomits and flatulence were also significantly reduced (p<0.0001).

CONCLUSION

The administration of an oral hyperproteic supplement with fibre in aged subjects who are undernourished or at risk of malnutrition can be done in nursing homes with a high level of compliance. Supplements improve their nutritional status and their intestinal habits.

Calcitriol improves streptozotocin-induced diabetes and recovers bone mineral density in diabetic rats

Vitamin D analogs exert a preventative effect on experimental diabetes, but whether or not they are able to halt progress of established diabetes is not yet known. Moreover, it is widely accepted that diabetes may induce osteoporosis, but the efficacy of vitamin D on diabetic osteoporosis is not clear. In order to help clarify these issues, we have tested the efficacy of calcitriol streptozotocin-induced diabetes. Streptozotocin (60 mg/Kg body weight) was injected in 3-month-old Wistar rats, randomly distributed into two groups: vehicle (olive oil) treated diabetic rats (D) and diabetic rats treated with 1.25-(OH)2D3 250 mg, three times a week (DT). Control animals (C) were treated with vehicle alone. The experiment lasted 8 weeks. The histology of the pancreata was evaluated. Blood glucose and calcium and phosphate in serum and urine were measured. Finally, bone mineral density (BMD) of tibia and lumbar vertebrae were evaluated. After 8 weeks, diabetes persisted in 85% of the diabetic rats (D group), but in only 45% of vitamin D-treated group (DT). At the end of the experiment, DT animals were separated into two groups, those still remaining diabetic (DT-NR) and reversed animals (DT-R). Moreover, bone loss was observed in diabetic animals (D), whereas BMD of DT-R rats showed similar values to those of controls (C). Our results suggest that 1.25(OH)2D3 improves diabetes and, as such, may recover BMD in streptozotocin-induced diabetic rats.

Influence of chronic ethanol consumption on the muscarinic cholinergic control of rat pancreatic acinar cells

There are a number of hypothetical explanations for the actions of ethanol on the exocrine pancreas; among them, the cholinergic hypothesis has received special attention. According to this hypothesis, chronic alcohol consumption induces alterations in the control of exocrine pancreatic function resulting in cholinergic hyperstimulation of pancreatic acinar cells and their muscarinic receptors. Our aim was to investigate the cholinergic control of pancreatic enzyme secretion and the number and affinity of muscarinic receptors in the pancreatic acinar cells of rats subjected to chronic ethanol ingestion. We also investigated whether a high-fibre diet modifies the actions of ethanol on these aspects of the exocrine pancreatic function. Four groups of rats received either a standard or a high fibre diet, and either water or 20% (v/v) ethanol. After 6 months of treatment, isolated pancreatic acini were used for the determination of carbachol-stimulated amylase secretion and for the analysis of muscarinic receptors, using 1-[N-methyl-3H]scopolamine as a radioligand. Neither chronic ethanol intake nor a high fibre diet caused any apparent alteration in pancreatic histology, neither did them modify plasmatic amylase levels. Chronic alcoholization resulted in a significant increase in the amylase released from pancreatic acini in response to carbachol stimulation, but it did not affect either the number or the affinity of pancreatic acinar muscarinic receptors. The actions of ethanol are not significantly modified by the simultaneous consumption of a high fibre diet.

Nitric oxide stimulates tyrosine phosphorylation of p125(FAK) and paxillin in rat pancreatic acini

Some of the effects of several oncogenes, integrins, growth factors, and neuropeptides are mediated by tyrosine phosphorylation of the non-receptor tyrosine kinase p125(FAK) and the cytoskeletal protein paxillin. We have demonstrated that different stimuli cause tyrosine phosphorylation of p125(FAK) and paxillin in rat pancreatic acini. The aim of the present study was to determine whether exogenous NO activates this pathway. We demonstrate that in isolated rat pancreatic acini, a NO donor, sodium nitroprusside (SNP) stimulates, in a dose- and time-dependent way, tyrosine phosphorylation of p125(FAK) and paxillin. The same effects could be observed after incubating acini with 8-Br-cGMP. Moreover, the stimulation caused by SNP was completely abolished by two different guanylyl cyclase inhibitors, methylene blue, and LY-83583. These inhibitors also diminished unstimulated phosphorylation of p125(FAK) and paxillin. We conclude that in rat pancreatic acini exogenous NO causes p125(FAK) and paxillin tyrosine phosphorylation that is mediated by a guanylyl cyclase-dependent pathway.

Low bone density with normal bone turnover in ovariectomized and streptozotocin-induced diabetic rats

Diabetes and estrogen deficit are known causes of osteopenia, diabetes being associated with a low bone turnover and estrogen deficit with a high bone turnover. In the present work, we studied the effect of combined ovariectomy and diabetes on bone mineral content (BMC) and bone mineral density (BMD) and several bone markers in the rat. Four groups of rats were studied: control (C), ovariectomized (O), diabetic (D), and ovariectomized and diabetic (DO). Twelve weeks after starting the experiments, BMC and BMD of the first six lumbar vertebrae were measured; a bone formation marker (BGP) and a bone resorption marker (free collagen cross-links, PYD) were also analyzed. Diabetic rats showed diminished gain in bone mass, BMC (D: 0.417 +/- 0.028 g, DO: 0.422 +/- 0.020 g) and BMDs (D: 0.171 +/- 0.006 g/cm2, DO: 0.174 +/- 0.006 g/cm2) both being significantly (P < 0.001) lower than those of control (C: BMC 0.727 +/- 0.024 g and BMD 0.258 +/- 0.004 g/cm2) and ovariectomized (O: BMC 0.640 +/- 0.044 g and BMD 0.240 +/- 0.009 g/cm2) groups. Moreover, the BMC and BMD of the C group were significantly (P < 0.05) higher than that of the O group. BGP and PYD levels were significantly (P < 0.01) higher in the O group (BGP: 138.2 +/- 16.8 ng/ml, PYD: 270.2 +/- 17.8 nM/mM) than those found in the control rats (BGP: 44.7 +/- 4.8 ng/ml, PYD: 165.6 +/- 12.5 nM/mM); the D group showed significantly (P < 0.01) lower values (BGP: 27.4 +/- 14.6 ng/ml, PYD: 55.0 +/- 7.4 nM/mM) than those of the control group. The DO group showed similar levels (BGP: 43.4 +/- 5.1 ng/ml, PYD: 146.7 +/- 14.6 nM/mM) to those found in the C group. Although bone marker levels in the O and D groups were in accordance with those expected in these situations, in the DO group the corresponding levels are apparently "normal." Also, the decrease of gain in bone mass observed after combining estrogen deficit and diabetes (DO group) did not seem to be more marked than that caused by diabetes alone.

Impairment of intracellular calcium homoeostasis in the exocrine pancreas after caerulein-induced acute pancreatitis in the rat

1. We have measured intracellular calcium concentrations in basal conditions and in response to cholecystokinin-octapeptide and acetylcholine in pancreatic acini isolated from rats with caerulein-induced acute pancreatitis and compared them with those in control rats. 2. We also measured amylase secretion in basal conditions and in response to cholecystokinin-octapeptide in both groups. 3. In pancreatic acini from rats with pancreatitis the basal intracellular calcium concentration was significantly increased (134.9 +/- 7.1 nmol/l compared with 71.8 +/- 2.9 nmol/l, P < 0.001). Moreover, the maximum values of intracellular calcium attained during the stimulation period were equivalent in acini from control and pancreatitic rats with no statistically significant differences. 4. In acini from control rats the differences between the resting levels of intracellular calcium and the maximum intracellular calcium values (delta[Ca2+]i) in response to several concentrations of cholecystokinin-octapeptide showed a clear dose-response relationship, with a half-maximal increase at 0.1 nmol/l and a maximal difference (delta[Ca2+]i = 259 +/- 50 nmol/l) at 1 nmol/l. In contrast, a right-shifted response, with a statistically significant smaller increase, was observed in acini from pancreatitic rats. 5. Basal amylase release was significantly higher in acini from rats with pancreatitis (11.7 +/- 1.0% of total compared with 5.9 +/- 1.1% of total, P < 0.001). In contrast, cholecystokinin-octapeptide and acetyl-choline-evoked amylase secretion was reduced by more than 85% in acini from pancreatitic rats. 6. In conclusion, calcium homoeostasis in pancreatic acinar cells from rats with caerulein-induced pancreatitis seems to be impaired. These results suggest excessive release of acinar free ionized calcium, or damage to the integrity of mechanisms that restore low resting levels of intracellular free ionized calcium, and the consequent calcium toxicity could be the key trigger in caerulein-induced acute pancreatitis.

Description of an automated method for the in vitro measurement of trypsinogen secretion from pancreatic segments

The characterization of trypsinogen output from superfused pancreatic tissue by an automated spectrophotometric method is described. To test the method we investigated the time-course and the dose-response curve for acetylcholine-induced trypsinogen release from superfused pancreatic segments. We have demonstrated that this method allows the on-line detection and estimation of trypsinogen release with suitability, stability, and sensitivity.

Effect of adenosine and adenosine agonists on amylase release from rat pancreatic lobules

The effects of adenosine on the amylase secretion from rat pancreatic lobules have been studied. Adenosine induces a dose-dependent stimulation on amylase release, which is maximal at a concentration of 10(-4) M. It has been observed a clear inhibition of this secretory action when atropine was added whereas no amylase release was seen in isolated acini after adenosine. The effect of adenosine is completely blocked by the adenosine receptors antagonist theophylline (10(-4) M), but not by dipyridamole (10(-3) M), a drug that inhibits the transport of adenosine into the cell. The increase of amylase secretion induced by adenosine is inhibited by either the relatively selective A1 receptor antagonist PD116,948 (10(-6) M) and by the A2 receptor antagonist PD115,199 (10(-6) M). Significant increases of amylase release are observed after the relatively selective A1 receptor agonist R-PIA (10(-5) M) and after the relatively selective A2 receptor agonist NECA (10(-4) M). Finally, the effect of R-PIA is not modified by coincubation with PD115,199 and the effect of NECA is not affected by coincubation with PD116,948. These results suggest that the action of adenosine is mediated through the release of acetylcholine and probably by the simultaneous occupation of both A1 and A2 adenosine receptors, whereas the intracellular action of adenosine could be discarded.

Heterogeneous decrease of bone mineral density in the vertebral column of ovariectomized rats

The long-term effect of ovariectomy on the loss of bone mineral density (BMD) was evaluated in rats with and without estrogen treatment; BMD was studied in the lumbar and caudal vertebrae, measured by DXA, to find how the losses of BMD occur in the axial skeleton. Seventy female Wistar rats of 3 months of age were divided into four groups as follows: group 1: control animals; group 2: ovariectomized animals; group 3: ovariectomized animals undergoing treatment with estrogen (0.25 mg/kg per week of 17-beta estradiol); group 4: ovariectomized rats undergoing estrogen treatment only during the last 3 months of the experimental period. No significant differences were found among the groups in regard to the BMD values of the caudal vertebrae at either 3 or 6 months. Likewise, in the lumbar vertebrae there were no significant differences among the groups after 3 months. However, at 6 months, a decrease in the BMDs of the ovariectomized animals with respect to the remaining groups was found: 226 +/- 11 mg/cm2 in the ovariectomized group; 262 +/- 14 mg/cm2 in the controls; 255 +/- 4 mg/cm2 in the rats receiving estrogen treatment for 6 months; and 259 +/- 5 mg/cm2 in the animals receiving estrogen for 3 months. The study also reveals the absence of differences in the bone mineral density between the ovariectomized and control rats when the former received estrogen treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-response effects of VIP on the rabbit exocrine pancreatic secretion. Comparison with PACAP-27 actions

A dose-response study of the effects of vasoactive intestinal peptide (VIP) on the exocrine pancreatic secretion of the rabbit has been made. Furthermore, the actions of VIP and pituitary adenylate cyclase activating peptide (PACAP) on the exocrine pancreatic secretion were compared at a similar molar dose. After the infusion of VIP a linear dose-response relationship for pancreatic flow rate and bicarbonate output, up to the dose of 4 micrograms/kg, was observed. VIP acts as a partial agonist of secretin, the rabbit pancreas being less sensitive to VIP compared with other mammals. Moreover, VIP did not significantly stimulate the pancreatic protein output. PACAP stimulated the hydroelectrolyte fraction of the exocrine pancreatic secretion in a similar manner to that of VIP. Unlike what was observed with VIP, PACAP, on the same molar basis, significantly stimulated the protein and amylase outputs. Furthermore, PACAP releases VIP, so that the action of PACAP on the hydroelectrolyte fraction may be partially mediated by VIP; on the other hand, VIP is not involved in the effect of PACAP on the pancreatic enzyme secretion of this species.

Cholinergic pathways are involved in secretin and VIP release and the exocrine pancreatic response after intraduodenally perfused acetic and lactic acids in the rat

The response of the exocrine pancreas to intraduodenal perfusion of acetic and lactic acids in normal and previously atropinized rats was studied. Secretin and vasoactive intestinal peptide (VIP) plasma levels in portal plasma were also measured. Intraduodenal perfusion of both acetic and lactic acids significantly stimulated flow rate (from 0.29 +/- 0.03 microliters/min to a maximum of 1.06 +/- 0.08 microliters/min after acetic and from 0.35 +/- 0.05 microliters/min to a maximum of 1.13 +/- 0.12 microliters/min after lactic acid perfusion) and protein output (from 11.16 +/- 2.33 micrograms/min to a maximum of 35.1 +/- 7.4 micrograms/min after acetic and from 8.98 +/- 0.95 micrograms/min to a maximum of 22.5 +/- 1.3 micrograms/min after lactic acid perfusion). Atropine treatment significantly inhibited pancreatic flow rate and protein output after acetic acid perfusion, but no inhibition of flow rate and a slight decrease in the protein output after lactic acid perfusion were seen. With respect to plasma peptide concentrations, significant increases in secretin and VIP levels were found after perfusion of both organic acids; atropine administration significantly decreased plasma secretin levels after acetic acid administration although it did not affect plasma VIP concentrations. By contrast, atropine significantly increased plasma secretin levels, but significantly lower values of plasma VIP concentrations were observed after lactic acid perfusion. Therefore, cholinergic mechanisms are involved in the release of secretin and VIP and different types of control of exocrine pancreatic secretion occur, depending on the features of the intraduodenal stimulant.

Platelet-activating factor mediates pancreatic function derangement in caerulein-induced pancreatitis in rats

1. We have assessed the role of platelet-activating factor in caerulein-induced acute pancreatitis (four subcutaneous injections of caerulein at a dose of 20 micrograms/kg) by measuring platelet-activating factor levels in portal blood, pancreatic tissue and peritoneal exudate in rats with and without pancreatitis. 2. We have also observed the effect of the platelet-activating factor antagonist, BN-52021, on the hyperamylasaemia and exocrine pancreatic secretion impairment associated with pancreatitis. 3. In rats with pancreatitis the basal pancreatic flow rate was increased (1.63 +/- 0.41 versus 0.25 +/- 0.03 microliters/min). Total protein output was similar in both untreated (5.98 +/- 1.93 micrograms/min) and caerulein-injected (6.5 +/- 2.0 micrograms/min) animals. Amylase output was lower in rats with pancreatitis (19.6 +/- 4.8 mu-units/min) than in controls (39.4 +/- 16.6 mu-units/min). 4. Caerulein-treated animals had significantly higher serum amylase levels than untreated animals. BN-52021 significantly reduced the caerulein-induced hyperamylasaemia. 5. Portal blood platelet-activating factor levels increased in rats with pancreatitis and in rats infused with cholecystokinin. Rats injected with caerulein and BN-52021 had portal blood levels of platelet-activating factor that were lower than those with pancreatitis. 6. Morphological derangements associated with pancreatitis (inflammatory infiltration and cell vacuolization) were also markedly reduced in BN-52021-treated animals. 7. The results of this study suggest that platelet-activating factor is involved in the development of caerulein-induced acute pancreatitis in rats.

Effects of acute intravenous ethanol on basal exocrine pancreatic secretion in rat: cholinergic involvement

The effect of intravenous infusion of ethanol on the basal exocrine pancreatic secretion of anesthetized rats was studied. The cholinergic involvement on the actions of ethanol was also studied using previously atropinized animals. During the stimulation period, pancreatic flow rate was significantly increased by intravenous ethanol in both un-atropinized (199% compared with basal) and atropinized rats (195% compared with basal). Pancreatic protein output was also increased during ethanol administration in both groups of animals (171% and 165% compared with basal in, respectively, un-atropinized and atropinized rats). After the administration of ethanol, in the poststimulation period, pancreatic flow rate was further increased only in the atropinized group of rats (290% compared with basal), whose values were significantly higher than those of ethanol-treated un-atropinized animals (195% compared with basal). A similar profile of response was observed in pancreatic protein output. Since intravenous ethanol did not stimulate either secretin or VIP release to portal plasma, the present results point to a direct effect of this substance on the exocrine pancreas. Furthermore, atropine revealed the existence of an inhibitory cholinergic effect of ethanol on the exocrine pancreas. In summary, results show that the effect of intravenous ethanol on the basal exocrine pancreatic secretion is dual and antagonistic.

Comparison between the effects of VIP and the novel peptide PACAP on the exocrine pancreatic secretion of the rat

The effect of intravenous infusion of pituitary adenylate cyclase-activating peptide (PACAP) 27, a novel regulatory peptide that shows a close structural and chemical similarity to vasoactive intestinal peptide (VIP), on the rat exocrine pancreatic secretion was studied. PACAP and VIP stimulated the flow rate of exocrine pancreatic secretion (p < 0.05). However, protein output and amylase secretion were mainly stimulated by PACAP. Intravenous infusion of VIP increased the plasma levels of secretin (p < 0.05). On the other hand, PACAP released neither secretin nor VIP. Our results show: (a) both PACAP and VIP stimulate exocrine pancreatic secretion, (b) PACAP stimulation of pancreatic amylase and protein secretion is greater than that induced by VIP, and (c) PACAP probably exerts a direct effect on exocrine pancreas whereas some of the actions of VIP might be mediated by secretin.

Mechanisms involved in the control of exocrine pancreatic secretion in the interdigestive state in the rabbit

The effect of rapid wash-out of the duodenum with phosphate buffered saline on exocrine pancreatic secretion and plasma levels of secretin, VIP, gastrin and CCK was studied. Furthermore, the possible nervous role in this effect was checked after atropine and hexamethonium treatment. Rapid wash-out significantly increased protein output (35.0 micrograms/min, in the control group without duodenal perfusion and 72.15 micrograms/min, in the perfused group) and the plasma levels of CCK (from 5.2 to 13.17 fmol/ml). Intravenous infusion of atropine significantly reduced the protein output (from 78.19 to 32.45 micrograms/min) and the plasma levels of CCK (from 10.1 to 5.55 fmol/ml), with no change in the remaining parameters in the intraduodenally perfused group. Intravenous administration of hexamethonium significantly stimulated hydroelectrolyte secretion (from 6.99 to 15.15 microliters/min) and the plasma levels of VIP (from 4.8 to 7.3 fmol/ml) and reduced the protein output (from 61.47 to 30.75 micrograms/min) and the plasma levels of CCK (from 14.56 to 6.25 fmol/ml) in the intraduodenally perfused group. Our results suggest that, in the interdigestive state, the exocrine pancreatic secretion of the rabbit is tonically inhibited. This inhibition can be divided into two different mechanisms: on the one hand there is a decrease in enzyme secretion produced by a duodenal factor and mediated by CCK and muscarinic mechanisms and on the other, there is an inhibition of hydroelectrolyte secretion with no duodenal participation which is probably controlled by nervous non-muscarinic mechanisms and VIP involvement.

Exocrine pancreatic response to intraduodenal fatty acids and fats in rabbits

1. The exocrine pancreatic secretion in rabbits after intraduodenal perfusion of, respectively, a short-chain fatty acid (propionate), a long-chain fatty acid (oleate) and a neutral fat (intralipid) has been studied. 2. Only the neutral fat and the long-chain fatty acid stimulated the hydroelectrolyte fraction of exocrine pancreatic secretion in a dose-related fashion, but this response was not mediated by secretin release. 3. Acinar secretion was more effectively stimulated after propionate perfusion than by oleate and this was governed by different mechanisms. 4. Neutral fat, without predigestion, stimulated the pancreatic enzyme secretion in the rabbit.

Nicotinic cholinergic influences in pancreatic secretion induced by intraduodenal alkaline and acid solutions in the rabbit

1. The effect of hexamethonium on the exocrine pancreatic response to intraduodenal acidification and alkalinization, and the secretin and VIP release after these stimuli, was studied. 2. The hydroelectrolyte secretion after hydrochloric acid and sodium carbonate perfusion was reduced by hexamethonium treated (322 +/- 44% of maximum response in flow rate to sodium carbonate perfusion in untreated animals vs 140 +/- 12% in pretreated animals, and 252 +/- 19% of maximum response in flow rate to HCl in untreated animals vs 166 +/- 11% in pretreated animals). 3. However, hexamethonium has no effect on secretin plasma levels after either intraduodenal acidification or alkalinization. 4. On the contrary, the ganglion blocker significantly (P < 0.01) reduced plasma VIP levels in response to intraduodenal HCl (maximum response 320 +/- 74% in untreated vs 184 +/- 44% in hexamethonium-treated animals). 5. Plasma VIP levels showed a similar increase in both untreated (maximum response: 151 +/- 12%) and ganglion blocked animals (170 +/- 26%) in response to sodium carbonate. 6. These data suggest the existence of complex neural mechanisms in the exocrine pancreatic response to intraduodenal stimuli, these mechanisms being different depending on the intraduodenal stimulus.

Dose-response effect of intraduodenal HCl on exocrine pancreatic secretion, portal secretin, and VIP plasma levels in anesthetized rats

In anaesthetized rats, a dose-dependent effect of different intraduodenal HCl loads (0.6, 1.2, 6 and 12 mmol/h) on exocrine pancreatic secretion and plasma levels of secretin and VIP has been observed. The flow rate of pancreatic juice showed a significant increase at all the doses used; the integrated percentage response (IPR) of flow were 359%, 595%, 894% and 1371% for, respectively, 0.6, 1.2, 6 and 12 mmol/h. The increase of protein output only achieved statistical significance at HCl loads of 6 mmol/h or more; the IPR of protein output were 153%, 305%, 320% and 420% for, respectively, 0.6, 1.2, 6 and 12 mmol/h HCl. Portal levels of secretin and VIP were measured by specific radioimmunoassays. Significant increase of secretin concentration was observed at HCl loads of 1.2 mmol/h or more, whilst VIP levels only increased significantly after intraduodenal HCl load of 6 mmol/h or more. The IPR of secretin release were 180%, 203%, 280% and 322% for, respectively, 0.6, 1.2, 6 and 12 mmol/h HCl and IPR of VIP release were 3%, 20%, 244% and 315% for, respectively, 0.6, 1.2, 6 and 12 mmol/h HCl. Our results suggest that secretin may play a more prominent role than VIP in stimulating exocrine pancreatic secretion in response to intraduodenal loads of acid in this species.

Effect of intraduodenal sodium bicarbonate in rat and rabbit exocrine pancreatic secretion

The effect of intraduodenal sodium bicarbonate, 0.1 M, on exocrine pancreatic secretion and the release of two peptides, secretin and VIP, was studied in anesthetized rats and rabbits, two species largely used in the gastroenterology laboratories. In the rabbit, intraduodenal sodium bicarbonate perfusion had no effect either on exocrine pancreatic secretion or on portal plasma levels of secretin and VIP. By contrast, in the rat, intraduodenal sodium bicarbonate perfusion significantly increased hydroelectrolyte exocrine pancreatic secretion and portal plasma secretin levels. A clear interspecific difference reflecting the different gastrointestinal physiology of both species is observed.

Cholinergic mechanisms for secretin release after intraduodenal alkalinization in the anaesthetized rabbit

Exocrine pancreatic response to duodenal perfusion with alkaline solutions (pH 11.4) was studied in the anaesthetized rabbit; secretin and vasoactive intestinal polypeptide (VIP) levels in portal plasma were measured and the contribution of cholinergic mechanisms was also evaluated. Intraduodenal perfusion of sodium carbonate stimulated flow rate and bicarbonate output to a maximum of 322 +/- 44 and 609 +/- 105% respectively compared with basal levels. Significant increases of plasma secretin levels, with a maximum of 267 +/- 38% as compared with basal, were also observed. A lower increase in VIP levels (maximum of 151 +/- 12%) was seen. All these effects, except the VIP response, were substantially inhibited by atropine. Our results show that exocrine pancreatic response to intraduodenal sodium carbonate is specifically focused on hydroelectrolytic secretion. Keeping in mind what occurs after intraduodenal alkaline phosphate buffer administration (at the same pH as sodium carbonate: 11.4) it seems that about 50% of the pancreatic response to sodium carbonate may be ascribed to pH and the remaining 50% to the carbonate anion. Moreover, this response would mainly be mediated by secretin, whose release can be facilitated by a cholinergic reflex.

Cholinergic mechanisms involved in the effect of intraduodenal ethanol on exocrine pancreatic secretion

The effect of intraduodenal ethanol on exocrine pancreas of the rat in basal conditions has been studied. The pancreatic flow rate significantly increased to a maximum of 148% of basal after intraduodenal ethanol whereas only slight increases of protein output were observed. Ethanol perfusion in previously atropinized animals also elicited a significant increase of the flow rate up to a maximum of 177% of basal values but this increase appeared later than that observed in non-atropinized animals. Our results show that the ethanol action is successively stimulant followed by a simultaneously dual and antagonic effect (stimulant and inhibitory). Furthermore, this ethanol effect is mediated by cholinergic mechanisms. Finally, no effect of ethanol on portal plasma secretin and VIP levels was observed in atropinized or non-atropinized animals.

Pancreatic dose dependent effect of intraduodenal HCl in the anesthetized rabbit

1. A dose-response relationship between intraduodenal perfusion of different HCl loads (1.8, 4.5, 9, 18 and 45 mmol/hr) and volume, bicarbonate and protein outputs, from the exocrine pancreas of anaesthetized rabbits was observed. 2. This study also shows a dose-response relationship between the different HCl loads and the porta levels of secretin and VIP. 3. The secretin response showed a marked decrease during the stimulation period and this may suggest the involvement of a neural mechanism. 4. The plasma VIP responses were of a magnitude that might suggest a hormone role for VIP in this effect.

Glucocorticoids effects on exocrine pancreatic secretion in caerulein-induced acute pancreatitis in the rat

The present work reports on exocrine pancreatic secretion in control rats, adrenalectomized rats and hydrocortisone-treated (10 mg/Kg/d) rats during 7 days, under normal conditions and after induction of acute pancreatitis with caerulein (20 micrograms/Kg) by 4 subcutaneous injections at hourly intervals. Pancreatic secretion was seen to be affected by the procedure of adrenalectomy, which led to a marked reduction in the secretion of proteins and amylase with respect to control values. This was probably due to the decrease occurring in the zymogen granules in the acinar cells of the exocrine pancreas, a phenomenon which also led to a decrease in pancreatic weight observed in these animals. Treatment with hydrocortisone induced a decrease in the secretion of proteins and amylase, as well as an increase in pancreatic weight. This agrees with the accepted hypothesis that large amounts glucocorticoids stimulate the synthesis and storage of proteins in the exocrine pancreas, reducing the secretory phase. The administration of high doses of caerulein under these conditions led to acute pancreatitis in the three groups of animals. This was paralleled by a dramatic decrease in protein and amylase secretion and by severe interstitial edema of the pancreas and by increases in serum amylase values. In the case of the animals treated previously with hydrocortisone, the latter were tripled with respect to the control animals. The conclusion is offered that since the storage of enzyme proteins is governed by glucocorticoids, which furthermore increase the sensitivity of the acinar cells to stimulation by secretagogues, the administration of these substances during the development of pancreatic lesions such as acute pancreatitis is highly compromising to the organism.

Caerulein-induced acute pancreatitis in the rat. Pancreatic secretory response to cholecystokinin

The response of pancreatic exocrine secretion to cholecystokinin (CCK), has been studied in experimental acute pancreatitis induced in rats by supramaximal doses of caerulein. Several doses of caerulein were used (4, 20 and 40 micrograms/Kg) and each one was administered by four subcutaneous injections over 3 h at hourly intervals. Pancreatic juice was collected 9 h after the first injection. The caerulein-treated animals showed a statistically significant increase in serum amylase levels. Secretory activity of ductular cells remained unchanged in all the caerulein-treated animals, but total protein and amylase secretion decreased significantly at all the caerulein doses used, both in resting conditions and under stimulation with CCK (1.25 micrograms/Kg/h). Despite this the acinar cells of rats treated with the lowest dose of caerulein retained a certain degree of secretory function since amylase activity in pancreatic juice was greater than in other groups of rats treated with higher doses of caerulein. Moreover, the percentage of increase observed in total protein and amylase in response to CCK respect to basal secretion is similar to that of the untreated animals. At higher doses (20 and 40 micrograms/Kg) the secretory capacity in response to CCK was inhibited. Therefore CCK administration in slight acute pancreatitis could be used as a therapy since it favours the secretion of pancreatic enzymes at percentual levels similar to those of the controls.

Release of substance P from rat hypothalamus and pituitary by endothelin

Endothelin-1 is a 21 amino acid peptide originally isolated from porcine aortic endothelium and has recently been localized within the central nervous system. We have administered endothelin-1 in a dynamic perfusion system in order to study its possible effects on the rat hypothalamus and anterior pituitary. Tissue (hypothalami or quartered pituitaries) was placed into plastic chambers and was perfused with oxygenated Krebs-bicarbonate solution. After an interval to establish stable basal peptide release, endothelin-1 was administered at two doses (0.1 and 1 microM) and the release of substance P, vasoactive intestinal peptide, 7B2, and somatostatin was measured, the last being detectable only in hypothalamic perfusates. Both concentrations of endothelin-1 led to a significant increase (P less than 0.01) in the release of substance P from the hypothalamus and pituitary, but not of vasoactive intestinal peptide, 7B2, or somatostatin. Thus after the 0.1 microM and 1 microM endothelin-1 perfusion substance P release from the hypothalamus increased by 125 +/- 5% and 215 +/- 15% (mean +/- SEM) of basal and from the pituitary by 168 +/- 8% and 276 +/- 15% (mean +/- SEM). No change occurred in the output of ACTH or other pituitary hormones. The release of substance P from hypothalamus or pituitary after stimulation with endothelin-1 was not blocked when a calcium free medium was used. Endothelin-1 binding sites were identified on rat pituitary cell membranes. These findings suggest the possibility that endothelin may act as a paracrine substance, neurotransmitter, or neuromodulator in the hypothalamo-pituitary axis.

Acinar cholecystokinin (CCK) receptors in the exocrine pancreas of the rat: effect of adrenalectomy

The binding of [125I]BH-CCK-8 to membranes of acinar cells from rats at 6 and 21 days after adrenalectomy was studied. The optimum conditions of time and temperature were previously established as being 120 min and 30 degrees C. Under these conditions, the membranes of the adrenalectomized animals of both groups (6 and 21 days) bound more radioligand than those from control rats. However, a qualitative study of the binding showed that the affinities of binding were much lower; in particular, the high affinity receptors had a Kd of 0.94 +/- 0.33 nM in the controls and this was 14.9 +/- 1.29 nM in the 6-day adrenalectomized animals, although the maximum binding capacity did not vary significantly. However, in the case of the low affinity receptors, there was a gradual increase in the maximum binding capacity as the time after adrenalectomy progressed: 717 +/- 121, 1,987 +/- 183, and 10,175 +/- 862 fmol/mg for the control, 6-day, and 21-day adrenalectomized rats, respectively. In the latter situation, the high affinity receptors completely disappeared. These results, which coincide with a marked deficit in protein secretion already described in adrenalectomized rats, can be accounted for in terms of the possible negative cooperativity exerted by the low affinity receptors on the high affinity hormone-receptor complex, the protein secretion of the acinar cells normally mediated by the high affinity receptors becoming paralyzed.

Effect of ACTH on VIP and galanin release from the pituitary

The effect of adrenocorticotropin (ACTH) on the release of four regulatory peptides from the anterior pituitary of male rats has been studied using an in vitro perfusion system. Quartered anterior pituitaries from male adult Wistar rats were perfused with buffer containing different concentrations of ACTH and, subsequently, 56 mM KCl. Fractions of 1.5 ml were collected at 3 min intervals and analyzed for vasoactive intestinal peptide (VIP), galanin, 7B2, and substance P, using specific radioimmunoassays. Concentrations of 0.02, 0.1, 0.2, and 0.4 microM ACTH produced increases of 117 +/- 50%, 155 +/- 90%, 163 +/- 14%, and 161 +/- 3% (mean + SE), respectively, of basal release of VIP (P less than 0.001). However, concentrations of 1 microM and 2 microM ACTH suppressed VIP release to 74 +/- 6% and 47 +/- 4%, respectively, compared to basal release (P less than 0.001). Results for galanin release were similar: concentrations of 0.02, 0.1, 0.2, and 0.4 microM ACTH increased galanin release to 129 +/- 4%, 136 +/- 8%, 143 +/- 9%, and 133 +/- 9% of basal release (P less than 0.001) and 1 and 2 microM ACTH provoked a suppression of 52 +/- 7% and 50 +/- 13%, respectively, compared with basal release (P less than 0.001). Doses of ACTH that altered the secretion of VIP and galanin had no effect on 7B2 and substance P release. These results demonstrate that ACTH causes a release of pituitary VIP and galanin in vitro and, moreover, that this is a biphasic phenomenon.

Duodenal alkalinization releases secretin and vasoactive intestinal polypeptide and stimulates exocrine pancreatic secretion in the anesthetized rat

The effect of various intraduodenal alkaline solutions (0.1 M NaHCO3, 0.1 M Na2CO3 and 0.025 M NaOH) on exocrine pancreatic secretion and the release of two peptides, secretin and vasoactive intestinal polypeptide, was studied in anesthetized rats. The flow rate of the pancreatic juice was stimulated up to a maximum of 179, 158 and 180% and the protein output up to 181, 131 and 162% (compared with basal) after duodenal perfusion of, respectively, 0.1 M NaHCO3, 0.1 M Na2CO3 and 0.025 M NaOH. Maximum increases in portal plasma secretin concentrations of 143, 146 and 190% and maximum increases in VIP of 116, 155 and 147% after, respectively, intraduodenal 0.1 M NaHCO3, 0.1 M Na2CO3, and 0.025 M NaOH were found. In conclusion duodenal alkalinization in the rat produces a pancreatic exocrine secretory response that may be partially ascribed to the effect of secretin and VIP.

Alpha-adrenergic influences on exocrine pancreatic secretion in the rabbit

Action of phenylephrine (35 micrograms/Kg/min) alone or previously blocked by phentolamine (100 micrograms/Kg/min) on exocrine pancreatic secretion of anaesthetized rabbits has been studied, in basal state or under stimulation by secretin (1 C.U./Kg/h) or by the octapeptide of cholecystokinin (OP-CCK) (0.15 Ivy dog units/Kg/h). Phenylephrine increased arterial pressure. This effect was blocked by phentolamine. However no variations were seen in pancreatic blood flow in any of the experimental conditions assayed. Phenylephrine produced a secretin-like effect on hydroelectrolytic secretion in basal conditions. This action was maintained after the infusion of secretin but not after OP-CCK. This effect was not blocked by phentolamine. Phenylephrine increased protein secretion in the basal state, an action that was blocked by phentolamine. After secretin or OP-CCK stimulation phenylephrine did not increase protein secretion. It is concluded that phentolamine blocks the effects of phenylephrine on acinar cells but not on ductular cells.

Plasma ferritin of sows during pregnancy and lactation

We studied a set of indicators of iron metabolism in sows and new-born piglets: hemoglobin, plasma iron, total iron binding capacity and plasma ferritin. Iron status of seventy-two sows was studied throughout pregnancy and lactation. The results point to mobilization of iron from its storage sites up to the second month of gestation, but no appreciable decrease during the second half of pregnancy. No appreciable mobilization of the iron stores of sows was observed during the lactation period. Nine sows and their 78 piglets were used to compare the status of iron in the sows and the end of gestation with the iron status of the piglets at birth; there was a positive correlation between the mean values of plasma ferritin concentration in the piglets and the levels of plasma ferritin in their mothers.

Exocrine pancreatic response to isoproterenol in the rabbit under secretin and CCK stimulation

The effect of isoproterenol (0.3 micrograms/Kg/min) on exocrine pancreatic secretion stimulated by secretin (1. C.U./Kg/h) and the octapeptide of cholecystokinin (OP-CCK 0.15 Ivy dog units/Kg/h) was studied in anaesthetized rabbits. Pancreatic blood flow remained unaffected by the action of isoproterenol; however, the administration of the beta-adrenergic agonist over an infusion of secretion an OP-CCK led to an increase in pancreatic juice flow (approximately 146% for secretin and 125% for OP-CCK) and HCO3-output (approximately 194% for secretin and 150% for OP-CCK), a potentiation being observed between the effects of secretin and isoproterenol. This kind of response, independent of vascular changes, is due to a direct action of isoproterenol on the ductular cells. Isoproterenol interferes with the action of secretin and OP-CCK in that it partially inhibits the stimulatory action of OP-CCK on the enzymatic secretion of the acinar cells in the rabbit pancreas and at the same time protein secretion decreases in the presence of secretin.

Effect of secretin on pancreatic juice proteins in caerulein-induced acute pancreatitis in the rat

Nine hours after the start of treatment with caerulein in rats, an increase in the weight of the pancreas and an increase in serum amylase levels were observed. Likewise, a significant increase in endogenous secretin occurred in rats with acute pancreatitis. A dramatic reduction in the secretion of total protein and amylase was also observed. A partial recovery of this latter effect was achieved after an infusion of high doses of secretin. Under our experimental conditions, the volume of secretion did not vary in caerulein-treated rats wtih respect to controls, either in resting conditions or under secretin stimulation, which indicates that the ductular cells were not significantly affected. Isoelectrofocusing (IEF) and crossed-immunoelectrophoresis (CIE) studies revealed important alterations in the proteins of the pancreatic juice of rats with caerulein-induced acute pancreatitis. Trypsinogen appeared to be particularly affected, showing an increase in the T2 acidic form with an IEP of 4.4 and a decrease in the basic form T3 with an IEP of 8.0, which splits in other forms with a clear antigenic community. A hydrolase was also observed with an IEP of 6.2. In this sense, secretin administration may also be said to induce a significant improvement in established acute pancreatitis, since it tended to normalize the structure and proportion of the proteins secreted.

Beta 1 and beta 2 adrenergic agonists in exocrine pancreatic secretion in the rabbit

The effect of Dobutamine (a beta 1-adrenergic agonist) and Terbutaline (a beta 2-adrenergic agonist) on exocrine pancreatic secretion was studied in anaesthetized rabbits, simultaneously controlling pancreatic blood flow and blood pressure. The secretion of fluid and ions (bicarbonate, sodium and potassium) was unaffected by the infusion of Dobutamine (8 micrograms.kg-1.min-1) or Terbutaline (10 micrograms.kg-1.min-1). Neither were pancreatic blood flow or mean blood pressure altered. Dobutamine or Terbutaline depress the function of the acinar cells, amylase secretion being more affected by the action of Terbutaline. The results show that beta 1 and beta 2-adrenergic stimulation has no effect on the ductular cells but does decrease the secretion by the acinar cells.

Alterations of pancreatic juice amylase by glucocorticoid levels in the rat

By use of isoelectrofocusing, three isoenzymes with pIs of 8.40, 8.55, and 8.65 were characterized in the amylase fraction of rat pancreatic juice. Enzyme secretion in rat exocrine pancreas is affected by glucocorticoid levels; adrenalectomy led to a significant decrease in protein secretion which was more pronounced in the amylase fraction, in which the isoenzymes with pI 8.55 and 8.65 disappeared. Substitution therapy with hydrocortisone (25 mg/kg/day, for 6 days) restored exocrine pancreatic secretion to almost normal levels. Administration of hydrocortisone to control rats led to structural alterations in enzymes secreted, splitting the amylase isoenzymes with pI 8.40; this was confirmed by crossed immunoelectrophoresis. It is concluded that glucocorticoid levels play an important role in the maintenance of function of exocrine pancreas and it is suggested that, although hydrocortisone fulfills the objective of restoring enzyme secretion diminished by adrenalectomy, it is possible that intensive treatment could have undesirable effects on the structure of enzymes and could involve pancreatic disfunctionality.

Influence of glucocorticoids on the secretion of pancreatic juice in the rat

The influence of adrenalectomy and hydrocortisone treatment on the exocrine pancreatic secretion has been studied in anaesthetized rats. In the adrenalectomized animals Na+ administered in the saline solution provided for drinking was able to maintain standard sodium levels in serum. In these animals an increase of Na+ secretion in pancreatic juice was observed. Furthermore, the osmotic effect created by the increase in Na+ would account for the increase in pancreatic flow. In these adrenalectomized rats, an increase in K+ output is observed, which can be explained by the high K+ concentrations in serum. Likewise adrenalectomy decreased pancreatic enzyme secretion and produced a loss in weight of the organ that is accounted for by a lack of glucocorticoids. Hydrocortisone administration did not affect neither the secretion nor the weight of the pancreas of the control rats but the hormone proved to be effective in adrenalectomized rats producing a pancreatic secretion close to normal, balancing the secretory rate of water, Na+ and K+, completely restoring total protein secretion and the weight of the pancreas but amylase secretion in part only. It is therefore concluded that the weight of the pancreas and its exocrine secretion are clearly influenced by adrenalectomy and by substitution therapy with hydrocortisone. The administration of this hormone (25 mg.kg-1.day-1 along 6 days) did not affect intact animals.

Response of exocrine pancreatic secretion to CCK in adrenalectomized rats

A study was made of the effect of adrenalectomy over different periods of time (6, 15 and 21 days) on exocrine pancreatic secretion in the rat in basal conditions and under stimulation with CCK. It was observed that adrenalectomy does not alter the rate of pancreatic flow but the response capacity to CCK is depressed. The secretion of total protein and amylase decreases significantly after sixth day, reaching the lowest levels after 21 days. Despite this, after 6 days the adrenalectomized rats showed the same capacity of response to CCK as the non-adrenalectomized animals, while after longer periods of time (15 and 21 days) the response to CCK was inhibited. The fact that the lack of glucocorticoids prevents the maturation of zymogen granules seems to be the main reason why the acinar cells do not increase protein secretion in response to CCK at 15 and 21 days after adrenalectomy. It is concluded that the sensitivity of exocrine pancreas to CCK and the amount of zymogen granules in the acinar cells decrease as a function of the time over which the animals are deprived of glucocorticoids.

Ox spleen ferritin: an isoelectrofocusing and crossed immunoelectrofocusing study

Ox spleen ferritin was purified and its purity checked by two-dimensional immunoelectrophoresis and polyacrylamide plate electrophoresis. Microheterogeneity was shown with a preparation of purified ferritin by isoelectric focusing. The protein was separated into at least 6 fractions; two large fractions in the 4.50-4.55 pH range and another 4 in the 4.65-4.80 interval. Microheterogeneity was confirmed in purified preparations by crossed immunoelectrofocusing. Seven fractions were observed, the most acid ones (4.50-4.55) also being the most abundant. In the crossed IEF procedure, exactness in the isoelectrophoretic separation time is important in that excessive time may impair the resolution potential.

Plasma ferritin and other parameters related to iron metabolism in piglets

The evolution of mean plasma ferritin values, hematocrit, hemoglobin, plasma iron concentration and total plasma iron binding capacity were studied during the growth of piglets from 0 to 50 days. The results obtained point to a massive mobilization of iron from storage sites during the second and third weeks of life of these animals. Apart from plasma ferritin values and the total plasma iron binding capacity, the coefficient of utilization may be considered as another parameter to be taken into account upon evaluating iron deposits in piglets.

[Variations in plasma ferritin during the transition from immature hens to mature ones in relation to laying]

The mobilization of iron stores during the transit from non laying to laying hen has been studied. A series of parameters related to iron metabolism (hemoglobin, hematocrit, plasma iron, transport iron binding capacity and plasma ferritin) have been determined during six consecutive weeks in which the setting percentage increased from 0 to 83%. Five male samples had been previously estrogenized to obtain a quick answer for the same parameters determined in the females. A decrease in plasma ferritin levels has been observed in both experiments, suggesting a mobilization of iron stores to the egg especially during the two weeks in which the setting percentage increase was highest (16-60%).

[Correlation between plasma ferritin and iron from liver and spleen in chicken (author's transl)]

Plasmatic, hepatic and splenic ferritin concentrations, measured by a radioimmunoassay method, have been studied in three groups of animals, with different iron status: In overload, in deficiency and control. Significant differences in plasmatic, hepatic and splenic ferritin concentrations were observed between overloaded and deficient animals. Simultaneously, liver and spleen ferritin iron values, significantly higher in overloaded than in deficient, were also found.

[Radioimmunoassay of plasma ferritin of Gallus domesticus L]

A new experimental procedure for chicken plasma ferritin based on the method of Luxton et al. has been carried out. All biologic reagents used were obtained in our laboratory: Ferritin from chicken liver, antiferritin antiserum from rabbits and anti-rabbit IgG from goat. Chloramine T procedure was applied to label ferritin with 125I. The iodinated protein was removed from free iodide by use of three chromatographic columns of Sephadex G-25, Sephadex G-200 and Sepharose 6B. Separation of the first antigen-antibody complex was carried out by the double antibody method. The assay working range covers from 21.8 up to 175 ng/ml. As ferritin concentration is higher in chicken plasma than in human, various plasma dilutions ranging from 1/16 to 1/64 were used.