摘要:

This study examines the potential role of the neuropeptide, galanin, in stress‐induced inhibition of insulin secretion in swimming mice. Firstly, the pancreatic and adrenal content of galanin‐like immunoreactivity was determined in mice after swimming stress. It was found that pancreatic content was significantly lower in stressed mice than in resting controls, both after 2 (P<0.05) and 6 (P<0.025) minutes of swimming, suggesting partial release of pancreatic galanin during stress. In contrast, the adrenal content of galanin‐like immunoreactivity did not change during the swimming stress. Gel filtration of tissue extracts indicated that (1) mouse pancreas contains two forms of galanin‐like immunoreactivity; one co‐eluting with synthetic porcine galanin (centred on Kavof 0.70) and another with a larger molecular weight (centred on Kav, of 0.30), and (2) mouse adrenal contains a small void volume‐peak and a larger peak of immunoreactivity, the latter co‐eluting with synthetic galanin. Secondly, the effects of swimming stress on plasma glucose and insulin levels were compared in mice that received high titre rabbit anti‐galanin serum with those in mice receiving normal rabbit serum. In normal rabbit serum‐pretreated swimming mice, glucose‐induced insulin levels were only 50% of resting controls (P<0.01). Immunoneutralization of galanin with specific antiserum abolished this swimming stress‐induced inhibition of glucose‐stimulated insulin levels. This was accompanied by a modestly enhanced rate of glucose disappearance. These findings suggest that pancreatic galanin is released during swimming stress in mice and that endogenous galanin makes a major contribution to stress‐induced impair

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09215.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Mice of both sexes were fed diets with 80 per cent animal or vegetable fat for 3 months. Half of the animals also received SuperEPA, which contains 61 % omega‐3 fatty acids. At the end of the feeding period the mice receiving animal fat had gained more weight than the controls and the mice receiving vegetable fat, and all fat diet groups, irrespective of sex or kind of diet, had become hyperglycaemic and had impaired intravenous glucose tolerance. The decay in plasma glucose during the tolerance tests was, however, significantly slower in the groups getting animal fat than in the groups getting vegetable fat. Supplementation with omega‐3 fatty acids only affected the male mice receiving the animal fat diet. Thus, these mice gained less weight, and both the hyperglycaemia and the impairment of the glucose tolerance were significantly less pronounced in this group than in the male mice fed animal fat without SuperEPA. In the groups eating fat diets, the plasma total cholesterol levels increased 50–100 per cent during the first 2 weeks of the experiment and then plateaued. In both sexes HDL‐cholesterol averaged approx. sixty‐five per cent of the total cholesterol content at the start of the experiment and was not changed significantly during the feeding period. It is concluded, that omega‐3 fatty acids do not seem to be suitable as a general means of ameliorating impaired glucose tolerance. It is further suggested that the fat‐fed mouse may be a useful animal model for further studies of the regulation of metabolism in ty

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09216.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The increase in the activity of ornithine decarboxylase, the key enzyme in the formation of polyamines, in the sublingual glands of the chloralose‐anaesthetized rat in response to stimulation of the parasympathetic innervation was enhanced by employing an intermittent pattern of nerve stimulation. 20 Hz in bursts delivered for 1 second every 10th second over a period of 3 hours increased the activity 1000‐fold, whereas a frequency of 2 Hz delivered continuously, and thus giving rise to the same total number of impulses as the burst stimulation, increased the enzyme activity only 50‐fold. Already 2 Hz in bursts caused the ornithine decarboxylase activity to increase. A parasympathetic non‐adrenergic, non‐cholinergic regulation of ornithine decarboxylase activity was shown in response to the two modes of stimulation. The increase to 2 and 20 Hz in bursts was 2‐ and 80‐fold, respectively, whereas it was 29‐fold to 2 Hz continuously. Increases in the concentration of the polyamine putrescine in response to burst stimulation of the parasympathetic nerve were found both in the absence and in the presence of atropine. The ornithine decarboxylase activity of the submaxillary gland was not affected by the parasympathetic stimulation. Stimulation of the sympathetic innervation was more effective in both types of glands, as to increases in the ornithine decarboxylase activity, when employing the continuous mode. In cultured tissue of the sublingual glands which,in vivo, had been subjected to parasympathetic stimulation in bursts (20 Hz), the syntheses of DNA and protein were increased as judged by the incorporation of radio‐labelled thymidine and leucine; in the presence of atropine the stimulation resulted only in increased syn

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09217.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Ten muscle spindle primary afferents from the extensor digitorum communis muscle of man were studied with single unit afferent recordings. Responses to slow test stretches with three different pre‐history conditions were assessed to investigate the contribution of rapid stretches to the stretch sensitization phenomenon. In two of the conditions, the slow test ramps were preceded by rapid stretch after which the parent muscle of the receptor was either (a) kept short for 5 seconds or (b) kept long for 3.2 seconds and then returned to the short muscle length for 5 seconds. The third condition (c) consisted of a slow stretch from short to long muscle length followed by a rapid return to the short muscle length, in turn followed by 5 seconds at the short muscle length.Afferent responses were depressed when the muscle had been kept at the long length after the rapid stretches (condition b) and enhanced when the muscle had been kept at the short length (conditions a&c). A prominent ‘initial burst’ was only present in the afferent discharge when the parent muscles of the primary endings had been kept short (condition a). A second, more prolonged burst was present for conditions (a) and (c) but was lacking or inconspicuous when the muscle had been kept long after rapid stretches (condition b). The rapid stretches in the stretch sensitization paradigm appear to be a primary factor not only for the enhanced responses of sensitized primary afferents but also for the depressed responses of desensitized primary affe

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09218.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Three different training regimens were performed to study the influence of eccentric muscle actions on skeletal muscle adaptive responses to heavy resistance exercise. Middle‐aged males performed the leg press and leg extension exercises two days each week. The resistance was selected to induce failure within six to twelve repetitions of each set. Group CON/ECC (n= 8) performed coupled concentric and eccentric actions while group CON (n= 8) used concentric actions only. They did four or five sets of each exercise. Group CON/CON (n= 10) performed twice as many sets with only concentric actions. Eight subjects did not train and served as controls. Tissue samples were obtained from m. vastus lateralis using the biopsy technique before and after 19 weeks of training, and after four weeks of detraining. Histochemical analyses were performed to assess fibre type composition, fibre area and capillarization. Training increased (P<0.05) Type IIA and decreased (P<0.05) Type IIB fibre percentage. Only group CON/ECC increased Type I area (14%,P<0.05). Type II area increased (P<0.05) 32 and 27%, respectively, in groups CON/ECC and CON/CON, but not in group CON. Mean fibre area increased (P<0.05) 25 and 20% in groups CON/ECC and CON/CON, respectively. Capillaries per fibre increased (P<0.05) equally for Type I and Type II fibres. Capillaries per fibre area for both fibre types, however, increased (P<0.05) only in groups CON and CON/CON. The changes in fibre type composition and capillary frequency were manifest after detraining. At this time only group CON/ECC showed mean fibre hypertrophy, while capillary density was elevated in groups CON/CON and CON. This study suggests that optimal muscle hypertrophy in response to resistance exercise is not attained unless eccentric muscle actions are performed. The data also show that heavy resistance exercise may produce muscle fibre transformation and capillary neoformatio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09219.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The effects of two different doses of thyrotropin‐releasing hormone on regional blood flows were studied in urethane‐anaesthetized rabbits pretreated with the α2adrenergic antagonists yohimbine and idazoxan. The effects of yohimbine were also studied using unanaesthetized rabbits. Blood flow measurements were performed using the tracer microsphere method. Thyrotropin‐releasing hormone was injected i. v. at a dose of either 0.1 mg kg‐1or 2.0 mg kg‐1. Yohimbine and idazoxan did not modify the effect of thyrotropin‐releasing hormone on mean arterial blood pressure. In the anaesthetized animals, blockade of the α2adrenoceptors resulted in a vasoconstriction in several peripheral organs and the vasoconstriction increased after thyrotropin‐releasing hormone administration. Pretreatment with yohimbine reduced total cerebral blood flow moderately and in such animals thyrotropin‐releasing hormone elicited only minor cerebral blood flow effects. Pretreatment with idazoxan did not reduce the total cerebral blood flow and in such animals it increased from 53± 1 to 75±4 g min‐1100 g‐1(P<0.01) after the administration of the lower dose of thyrotropin‐releasing hormone and from 64±5 to 112±17 g min‐1100 g‐1(P<0.01) after the higher dose.In the conscious animals, yohimbine caused an increase in mean arterial blood pressure and heart rate. Vascular resistance increased in several organs. The cerebral blood flow decreased in white matter (P<0.05) and the caudate nucleus (P<0.05).The results indicate that there is a yohimbine‐sensitive mechanism involved in the cerebrovasodilating effect of thyrotropin‐releasing hormone in anaesthetized rabbits. There is also an activation of the sympathetic nervous system by thyrotropin‐releasing hormone which results in increased vascular resistance and mean arterial blood pressure. Its effect on the vascular resistance may be enhanced by α2adrenoceptor blockade. In conscious animals, there seems to be a yohimbine‐sensitive mechanism involv

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09220.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We have investigated the regulation of mRNA levels of alpha‐ and beta‐subunits of guanine nucleotide‐binding regulatory proteins (G proteins) by peptide hormones in prolactin producing rat pituitary adenoma cells (GH3cells) in culture. The cells were treated with thyroliberin (1μm), vasoactive intestinal peptide (1μm) or somatostatin (10μM) for 6 to 48 hours. Thyroliberin and vasoactive intestinal peptide increased the levels of GsαGoα, Gi‐2α, Gi‐3α, Gxα, Gβ36and Gβ35mRNAs. The effect of vasoactive intestinal peptide was however earlier and more pronounced. Gi‐2αmRNA levels showed the quantitatively largest alterations. Somatostatin upregulated Gsα and downregulated Goαand Gi‐2mRNAs. G protein mRNAs for Gi‐2αand Goαwere increased by exposure of the cells to a medium devoid of serum. We conclude that G protein mRNA levels are subjected to alterations by hormones that act through the corresponding G proteins in the regulation of pro

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09221.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A comparative study was made of the ERG b‐ and d‐wave intensity‐response functions before and after GABAergic blockade by means of 0.4 mmol 1‐1picrotoxin. A wide range of background intensities, including part of the high photopic range, were used. The intensity‐response functions of both the ERG waves fitted well to the Michaelis‐Menten equation (V/Vmax= In/(In+s̀n). A s̀‐value decrease and a Vmaxandnincrease were observed after picrotoxin treatment. The analysis of the intensity‐response functions shows that, under a wide range of backgrounds, the GABAergic neurons influence theon‐ andoff‐response in the distal retina in a similar way. They decrease the gain and the contrast gain of the b‐ and d‐wave generating neuronal mechanisms and widen the intensity span of their responses under given background illumination. The GABAergic system is involved also in ‘response scaling’ in theon‐andoff‐channels in the distal retina. A very important effect in this respect seems to be the equalization of the range of the responses to increment st

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09222.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

In man, about half the intravascular granulocytes are not freely circulating, but temporarily sequestered (‘marginated’), so that they cannot be retrieved by bleeding. Where and how the sequestration occurs is not settled and is the subject of the present report. Isolated autologous rabbit granulocytes, labelled with two different99mTc methods, were reinjected and followed with external scintigraphy.Intraarterial as well as intravenous injection led to rapid accumulation of radioactivity over the lungs. This finding was corroborated and extended by similar experiments, where the labelled cells had firstly been passed through an intermediary rabbit host to remove altered cells, i. e. cells damaged, ‘primed’ (pre‐activated), or activated. In the final autologous host about two thirds of the label rapidly localized to the lungs and liver, and a few per cent to the spleen (which is very small in the rabbit). Even though more than half of the intermediary rabbit's calculated blood volume was removed, the blood sample contained only a few per cent of the rabbit's radioactivity; consequently, many of the labelled leucocytes had marginated during the bleeding. The proportional distribution of radioactivity over lungs, spleen, kidneys, and the rest of the intermediary animal was not markedly changed by this exsanguination, but there was a 4–20% decrease over the liver.Taken together, our findings indicate that normal granulocytes marginate in lungs, liver, and spleen ‐ apparently explicable by the effects of cell size, vessel diameter, cell stiffness (visco‐elastic properties) and size of the arterio‐venous hydrostatic pressure difference. The liver and spleen seemed to play additional roles, since radioactivity over these organs decreased much slower than expected from reported blood half‐times of intact and slightly damaged rabbit granulocytes. This led to a suggestion that macrophages exposed to blood normally phagocytose apoptotically

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09223.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1991.tb09224.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY