The influence of different nutrients on plasma cholecystokinin levels in the rat

Summary Isocaloric and isovolemic amounts of protein (casein), fat (intralipid) and carbohydrate (saccharose) and an isovolemic control solution of water were administered intragastrically to conscious rats. The plasma CCK levels, determined by a sensitive and specific radioimmunoassay, showed an increment of 6.3±0.6, 2.7±0.5, 1.7±0.4 and –0.9±0.4 pM, respectively (basal value 2.5±0.3 pM). The threshold increment of plasma CCK to stimulate pancreatic enzyme secretion by exogenous CCK was found to be 1.5 pM. It is therefore concluded that casein is a potent stimulus for CCK secretion and pancreatic secretion, but that fat and even carbohydrate, although less potent, also produce a CCK increment above the threshold for pancreatic secretion.Supported by Grant IKW 86-16 from the Netherlands Cancer Foundation KWF.     

Effect of hyperkalemia on insulin secretion

The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68 +/- 0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p less than 0.05). We concluded that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Factors influencing the intestinal phase of pancreatic exocrine secretion in the turkey

The present study was done to investigate the factors regulating the intestinal phase of exocrine pancreatic secretion in the turkey. The intestine of turkeys equipped with pancreatic fistulas was perfused with peptone solution, fat emulsion and hydrochloric acid (HCl), and pancreatic flow and protein output were measured. Neither peptone solution nor fat emulsion had any effects on pancreatic secretion. HCl enhanced the flow rate of pancreatic juice but not protein output. To clarify the neural mechanism of this phenomenon, the vagal postganglionic blocker atropine was continuously infused and pancreatic secretion in response to intestinal HCl was measured. Atropine completely suppressed both pancreatic flow and protein output. It is suggested that the avian intestinal phase of pancreatic secretion is mainly controlled by cholinergic action though HCl stimulation.     

Endocrine and exocrine pancreatic function after camostate-induced growth of the organ

It is well known that oral administration of camostate induces hyperplasia and hypertrophy of the rat pancreas. It is not clear, however, whether pancreatic hormone and enzyme secretion are affected by camostate treatment.In rats, daily administration of 200 mg camostate/kg b. wt for 14 days significantly increased pancreatic weight and pancreatic content of DNA, protein, amylase, lipase, trypsin and chymotrypsin, as well as the amount of insulin, glucagon and somatostatin. In the intact animal, blood glucose levels and serum concentrations of insulin and glucagon in response to an oral glucose load were not impaired after camostate treatment. In the isolated perfused pancreas, however, insulin and glucagon secretions were reduced, whereas somatostatin release was not affected. The volume of pancreatic juice produced by the unstimulated isolated perfused organ, as well as protein and enzyme secretion, were increased after camostate treatment. Likewise, the isolated perfused pancreas from camostate-treated rats secreted a larger volume of pancreatic juice and more protein in response to cholecystokinin (CCK), while enzyme secretion was affected in a non-parallel manner: amylase release was markedly reduced, lipase release was unchanged, and release of trypsin and chymotrypsin was increased.     

The action of the cholecystokinin-A receptor antagonist,devazepide, on the digestive system of the chicken

The influence of the cholecystokinin (CCK)-A receptor antagonist, devazepide (DVZ), on the chicken digestive tract was investigated. The passage of food from the crops of birds treated with DVZ was not significantly different from that of the control. DVZ treatment did not inhibit the biliary flow stimulated by the CCK analogue, caerulein. Dispersed chicken pancreatic acini stimulated with CCK were treated with various concentrations of DVZ. At 10^–5 M, DVZ completely inhibited amylase release; this concentration was much higher than those reported to have similar effects in mammals. The results suggest that the action DVZ as a CCK antagonist in the chicken is very weak.     

Reduction of body fat stores by inhibition of prolactin secretion

Reductions of prolactin secretion by bromocriptine treatment for 24 days reduced fat stores (abdominal and epididymal fat depots) in hamsters by 25-49% compared with control animals. However, body weights and food consumption were not affected. These results further substantiate an important role for prolactin in regulation of fat metabolism and indicate that bromocriptine might be used to decrease fat stores.     

Effect of long acting somatostatin-analogue, SMS 201 995, on gut hormone secretion in normal subjects

SMS 201 995 is a new long acting analogue of somatostatin. We have investigated its effect on basal and meal stimulated secretion of gut hormones and have shown that after a single s.c. injection of 50 micrograms it lowers significantly the basal plasma levels of pancreatic polypeptide, secretin, motilin, pancreatic glucagon and insulin, it also effectively suppresses the postprandial release of pancreatic polypeptide, gastrin, secretin, gastric inhibitory peptide, pancreatic glucagon and insulin. Except for the usual brief discomfort of an injection, no symptoms or untoward effects were observed.     

Absorption of pancreatic lipase from the duodenum into lymphatics

Summary A significantly higher lipase activity was measured in the duodenal lymph samples of 15 dogs than in each of corresponding arterial blood plasma samples collected prior to, during and after maximal hormonal stimulation of pancreatic secretion. The result may be evaluated as a sign of pancreatic lipase absorption by the duodenum into lymphatics.     

Effect of hyperkalemia on insulin secretion

Summary The effect of hyperkalemia on insulin secretion remains undefined. We evaluated portal and peripheral insulin levels in anesthetized dogs after infusions of KCl. The mean maximal increase in peripheral plasma potassium at infusion rates of 0.2 mEq/kg/h was 0.68±0.20 mEq/l. There were no significant increases in either portal or peripheral insulin levels. In contrast, in six dogs whose plasma potassium concentration increased in each case by more than 2.0 mEq/l (infusion rate of 0.5 mEq/kg/h), portal insulin levels increased fivefold (p<0.05). We conclude that only marked increases in plasma potassium concentration stimulate pancreatic insulin secretion.     

Stimulation of calcitonin secretion in the fasting newborn rat by ingestion of triglycerides]

The stomach gavage of fat (triglycerides) in the fasting newborn Rat induced a marked increase in the plasma concentration of immunoreactive calcitonin after 30 and 60 mn. Calcium chloride given by the same route at the dose of 20 mg calcium per kg body weight had a poor effect on calcitonin secretion. This stimulation was probably mediated through some gastro-intestinal hormone that has to be uncovered.     

Cholecystokinin is not a major regulator in the digestive system in the chicken

To find out whether physiological concentrations of cholecystokinin (CCK), a gastrointestinal hormone in mammals, are also active in chickens, the pancreatic amylase secretory response to CCK-8 was investigated in vitro. Rat pancreatic acini responded to the physiological concentration of CCK-8, but in chickens amylase release was induced at a concentration of CCK-8 1000 times higher than that observed in rats. In another experiment, biliary flow was tested with several doses of CCK-8. The bile flow was stimulated in a dose-dependent fashion, but a significant enhancement was not obtained at a concentration of 0.5 g CCK-8/kg body weight, which was considerably higher than physiological ones. It is concluded that endogeneous CCK does not have an important role in the digestive system in the chicken.     

氧化酪蛋白对小鼠组织抗氧化能力及血液肽组成的影响

目的研究酪蛋白经过加热氧化和脂质过氧化物MDA氧化后,对小鼠体内氧化还原状态及小鼠血液中肽组成的影响。方法酪蛋白经100℃加热（0、30、60、90min）和丙二醛（MDA）氧化（MDA终浓度0、0．2、20、200mmol／L）处理,测定其羰基、巯基含量及表面疏水性的变化。小鼠分为四组,分别灌胃生理盐水、正常酪蛋白、加热90rain、MDA氧化酪蛋白,测定0、30、60、90、120、160min血液中自由基水平,并采用HPLC-MS分析灌胃后120min小鼠血浆肽组分的变化,测定小鼠的肝脏、空肠、十二指肠组织抗氧化能力指标（总抗氧化能力T—AOC、丙二醛MDA、还原型谷胱甘肽GSH）。结果酪蛋白经过两种氧化处理,羰基含量均随氧化程度呈显著上升,巯基含量呈下降趋势。加热氧化后酪蛋白表面疏水性比正常酪蛋白低,而MDA氧化导致疏水性上升。小鼠血液中自由基最高峰出现在灌胃后160min。灌胃两种方式处理的酪蛋白,血液中自由基的含量均显著高于灌胃正常酪蛋白组（P〈0．05）,肝脏、空肠、十二指肠还原型谷胱甘肽（GSH）含量和总抗氧化能力（T-AOC）均低于正常酪蛋白组,丙二醛（MDA）含量显著提高（P〈0．05）。HPLC—MS分析显示,灌胃MDA氧化酪蛋白组血液中肽组成与对照组不同,出现c7H15N4O含羰基类的物质：结论氧化会导致酪蛋白理化性质的改变,摄入氧化酪蛋白引起机体的氧化应激,降低组织抗氧化能力。     

Effect of long acting somatostatin-analogue,SMS 201995, on gut hormone secretion in normal subjects

Summary SMS 201 995 is a new long acting analogue of somatostatin. We have investigated its effect on basal and meal stimulated secretion of gut hormones and have shown that after a single s. c. injection of 50 g it lowers significantly the basal plasma levels of pancreatic polypeptide, secretin, motilin, pancreatic glucagon and insulin, it also effectively suppresses the postprandial release of pancreatic polypeptide, gastrin, secretin, gastric inhibitory peptide, pancreatic glucagon and insulin. Except for the usual brief discomfort of an injection, no symptoms or untoward effects were observed.     

[3H]-Norcocaine and [3H]-pseudococaine: Effect of N-demethylation and C2-epimerization of cocaine on its pharmacokinetics in the rat

Summary After i.v. injections of cocaine, norcocaine, pseudococaine to the rat, the T_1/2 in brain were 0.4, 0.6, 0.2 h respectively and in plasma 0.4, 0.5, 0.2 h respectively. Benzoylnorecgonine and norecgonine were the metabolites of norcocaine in brain. Pseudonorcocaine, pseudobenzoylnorecgonine, pseudobenzoylecgonine and pseudoecgonine were the metabolites of pseudococaine in rat brain. Benzoylnorecgonine and pseudobenzoylecgonine had potent stimulant activity intracisternally in the rats.Acknowledgment. This work was supported by U.S. Army Medical Research and Development Command Contract No. DADA-17-73-C-3080.     

Dissociation of digoxin-like immunoreactivity and Na+,K+-ATPase inhibitory activity in rat plasma

We measured endogenous digitalis-like factor (EDF) in rat plasma during acute saline infusion by two different procedures. Na+,K+-ATPase inhibitory activity in the rat plasma significantly increased during saline loading (7.8 +/- 2.2 vs 2.5 +/- 0.9%, with and without acute saline loading, respectively, p less than 0.05). On the other hand, the plasma digoxin-like immunoreactivity significantly decreased during acute saline loading (16.9 +/- 1.6 vs 32.0 +/- 2.8 pg digoxin equivalents/ml, with and without acute saline loading, respectively, p less than 0.01). These results indicate that the major substances detected by digoxin-like immunoreactivity and direct Na+,K+-ATPase inhibitory activity are completely different, at least in rat plasma.     

Denaturation map of the ribosomal DNA of Lytechinus variegatus sperm.

Electron microscopy of the partially heat denatured ribosomal DNA (rDNA) from sea urchin (Lytechinus variegatus) sperm has demonstrated that it consists of repeating units of 3.6 +/- 0.2 micron, corresponding to a mol.wt of 7.2 +/- 0.4 x 10(6). Based on differential denaturability, each repeat unit is divided into 2 regions. The larger region of 2.47 +/- 0.11 micron (mol.wt 4.9 +/- 0.22 x 10(6)) corresponds in length to the ribosomal precursor RNA of sea urchins and the smaller, GC-rich, subunit of 1.16 +/- 0.09 micrometer (mol.wt 2.3 +/- 0.18 x 10(6)) is presumed to contain non-transcribed spacer sequences.     

Effects of blood sampling, anesthesia and surgery on plasma vasopressin concentration in rats.

The influence of blood sampling, anesthesia and surgery on plasma vasopressin concentration was assessed in rats. Mean plasma concentration in conscious, chronically catheterized rats was 1.4 +/- 0.1 pg/ml (n = 6). This value remained constant over repeated plasma samplings in the same animals. On the other hand, decapitation increased the plasma vasopressin concentration to 6.0 +/- 2.4 (in pg/ml) (n = 6), inactin anesthesia to 2.9 +/- 0.6 (n = 6), anesthesia and femoral cannulation to 13.3 +/- 5.8 (n = 6) and surgery for renal micropuncture to 81.3 +/- 35.0 (n = 6). It is concluded that the level of circulating plasma vasopressin is highly dependent on the sampling technique and is closely related to the extent of surgery.     

Reduction of body fat stores by inhibition of prolactin secretion

Summary Reductions of prolactin secretion by bromocriptine treatment for 24 days reduced fat stores (abdominal and epididymal fat depots) in hamsters by 25–49% compared with control animals. However, body weights and food consumption were not affected. These results further substantiate an important role for prolactin in regulation of fat metabolism and indicate that bromocriptine might be used to decrease fat stores.     

Changes in mammary tissue lipid metabolism in the goats during the first 2 months of lactation]

5 French Alpine Goats were studied after normal or premature parturition. Mammary tissue acetyl-C oA carboxylase, glucose-6-phosphate dehydrogenase, malic enzyme and lipoprotein lipase (LPL) activities varied in parallel with milk fat secretion from the 3rd to the 9th week of lactation. Variations of mammary LPL activity and of long chain fatty acid secretion were positively highly correlated during that period. In goats with normal parturition, lipogenic activities seemed to reach a maximum level shortly after parturition. There was a positive correlation between mammary Ll activities and plasma non esterified fatty acid contents, possibly reflecting a relationship between adipose tissue mobilisation and mammary metabolism.     

The responsiveness to (1-24) ACTH of Mongolian gerbil adrenals superfused in vitro as a function of basal secretion

Wide variations have been found in the responsiveness to (1-24)ACTH of Mongolian gerbil adrenal glands superfused in vitro. These variations were not correlated to corticosteroid plasma levels or to adrenal weights. In contrast, (1-24)ACTH-stimulated secretion greatly depended on basal in vitro secretion (quarters: r = 0.97, p less than 0.01; slices: r = 0.90, p less than 0.001) indicating that the fine adjustment of basal corticosteroidogenesis forms an important part of the regulatory mechanisms modulating (1-24)ACTH-stimulated corticosteroid secretion in vitro.