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Biomedical subjects

M Papp

Publications and source records attributed to M Papp.

At least 91 records · Page 5Linked to original sources
PubMed1988

Different effects of short- and long-term treatment with imipramine on the apomorphine- and food-induced place preference conditioning in rats.

The effect of imipramine (IMI) on the rewarding properties of pharmacological and natural reinforcers was studied with a place preference paradigm. The pairing of distinctive environmental stimuli with either injection of different doses of apomorphine (APO) or presentation of food to hungry rats resulted in a conditioned preference for those stimuli. The development of APO- and food-induced place preference was prevented by short-term administration of IMI. In contrast, long-term pretreatment with IMI significantly potentiated the APO- and food-induced conditioned effect. In separate experiments aversive properties of IMI by itself were also found, as the conditioned avoidance response to the environmental stimuli paired with administration of single doses of IMI was demonstrated. The results indicate an enhancing effect of the long-term IMI administration on the dopamine-mediated reward functions and the rewarding value of natural reinforcers.

Animals↗
PubMed1988

Effect of bombesin and its mammalian counterpart, GRP, on exocrine pancreas in the rat.

The effect of equimolar doses (6 nmol/kg) of bombesin and its mammalian counterpart, GRP, on pancreatic growth and secretion was studied in adult rats. Both peptides were administered intraperitoneally three times a day for 5 consecutive days. Saline-treated rats were used as controls. At the end of the treatment, animals were anaesthetized and pancreatic juice was collected in basal conditions and after caerulein (0.75 nmol/kg i.p.) stimulation. Afterwards, the rats were sacrificed and growth and composition of the pancreatic tissue were determined. Compared with the control (saline) values, either basal or stimulated secretion was significantly increased after short-term treatment with both peptides. In addition, both bombesin and GRP increased pancreatic weight, total pancreatic protein, trypsin and amylase content. The DNA content was also increased by both peptides, although only the GRP effect proved to be significant. These results demonstrate that both bombesin and GRP have a growth-promoting effect on rat pancreas and concomitantly increase its secretory capacity. The mechanism of this peculiar biological action is likely to be connected with a direct stimulatory action on the gland.

Amylases↗
PubMed1988

Excessive doses of cerulein stimulate pancreatic growth in suckling rats but damage the pancreas of weaned rats.

The cerulein-stimulated pancreatic growth response was evaluated in 4- and 11-day-old female suckling CFY rats and compared with the pancreatic response of cerulein-treated 24-day-old weaned rats. Cerulein was given subcutaneously in saline in 1-, 10- and 100-micrograms/kg doses t.i.d. The increase in pancreatic DNA content was regarded as an index for hyperplasia, and the increase in pancreatic weight, protein content and enzyme activity related to milligrams of DNA as an index for hypertrophy. Three-day administration of 1- and 10-micrograms/kg doses of cerulein increased the pancreatic trypsin/DNA ratio, and doses of 100 micrograms/kg cerulein evoked pancreatic hypertrophy and hyperplasia in 4-day-old rats. Ten-day administration of 1- and 10-micrograms/kg doses induced pancreatic hypertrophy and hyperplasia, while the 100-micrograms/kg doses induced pancreatic hypertrophy in 11-day-old rats. In 24-day-old weaned rats, the 3-day administration of 1-microgram/kg doses resulted in hypertrophy of the gland, while the 100-micrograms/kg doses of cerulein evoked pancreatic aplasia and atrophy. It is concluded that the growth-promoting effect of cerulein on the newborn rat pancreas is age- and dose-dependent.

Amylases↗
PubMed1988

Caerulein in supramaximal doses fails to stimulate pancreatic growth, but it forces secretory granulopoiesis.

To determine how low or high dose of caerulein, a cholecystokinin analogue influence pancreatic growth, doses of caerulein were selected which were submaximal (1 microgram/kg i.p.) and supramaximal (10 micrograms/kg i.p.) for enzyme protein secretion. Rats were injected every 8 h for 7 days with saline, low, or high dose of caerulein. The low dose of caerulein significantly increased pancreatic weight and content of DNA, protein, and digestive enzymes. The high dose caerulein group did not differ from control in these parameters of pancreatic growth. The number of zymogen granules was increased in both caerulein-treated groups. However, zymogen granules in the high dose group were atypical, appearing lucent or having a dense core with a lucent halo. These results indicate that caerulein has a biphasic effect on both enzyme secretion and the trophic response of acinar cells, and that the inhibitory effect of high dose of caerulein on pancreatic growth is accompanied by alterations in acinar cell morphology.

Amylases↗
PubMed1987

Bombesin promotes pancreatic growth in suckling rats.

UNLABELLED: The pancreatic growth promoting effect of long term administration of bombesin was investigated in suckling rats. The authors showed that bombesin given in 10 micrograms/kg b.wt doses s.c. every 8 h for 10 days from the day of parturition stimulated pancreatic growth: it increased pancreatic weight, protein and DNA content, trypsin and amylase activity and trypsin/DNA ratio. CONCLUSION: Bombesin is an effective stimulator of pancreatic growth in suckling rats.

Aging↗
PubMed1987

Caerulein stimulates pancreatic growth and somatic growth in suckling rats.

This study deals with the stimulatory effect of caerulein on pancreatic and somatic growth in CFY suckling rats before weaning. After birth, caerulein (0.25, 0.5, 1, 3, 10 and 30 micrograms/kg) was given subcutaneously (s.c.) 3 times daily for 10 days. Saline-treated newborn rats were used as control. Caerulein increased pancreatic weight and total pancreatic trypsin activity reaching the maximum at 1 microgram/kg dose; higher doses did not cause higher values. On this basis 1 microgram/kg caerulein was applied s.c. 3 times daily for 3, 5, 10 and 20 days. At the end of the treatment pancreatic weight, total pancreatic protein, DNA content, trypsin and amylase activity was measured. Increases in body weight due to caerulein treatment were found from 6 days of treatment. Caerulein treatment increased pancreatic weight, total pancreatic DNA and protein content, and trypsin and amylase activity when applied for 5, 10 and 20 days. Treatment for 3, 5, 10 and 20 days with caerulein preferentially increased pancreatic trypsin activity compared to amylase activity. Trypsin activity per mg DNA increased with time in each caerulein-treated group demonstrating that the effect of caerulein increases with duration of treatment. In the saline-treated control group, however, pronounced increase in pancreatic amylase activity compared to that of trypsin activity was found in the age between days 11 and 21. This may be explained by the observation that the plasma corticosterone level increased during this period of postnatal life. The effect of caerulein in promoting pancreatic and somatic growth of suckling rats before weaning may be attributed to a specific enhancing effect of the peptide on proteolytic (e.g. trypsin) enzyme production of the pancreas.

Amylases↗
PubMed1987

Separation of the motivational and motor consequences of 6-hydroxydopamine lesions of the mesolimbic or nigrostriatal system in rats.

The effects of 6-hydroxydopamine (6-OHDA) lesions in the ventral tegmental area (VTA) or substantia nigra, pars compacta (SN/pC) on the behaviour of hungry rats were examined in a Columbia obstruction box test. The lesions of dopaminergic neurones in the VTA as well as in the SN/pC decreased the number of crossings of an electric obstruction for food. After the lesion in the VTA the reaction of rats became independent of the level of hunger--the number of their crossings was similar at different levels of hunger. In contrast, no effect of the lesion was found when the animals were trained and tested in the absence of shock. The 6-OHDA lesion in the SN/pC also decreased the number of crossings, but the animals remained sensitive to motivational hunger stimuli: they were still crossing the obstruction in a hunger-dependent manner. Lesions in neither the VTA nor the SN/pC significantly altered the spontaneous food intake and sensitivity to painful electric stimuli. In the Rotarod test only the SN/pC-lesioned rats showed a substantial motor impairment; lesions in the VTA had no effect in that test. The obtained results are discussed in terms of the role of the dopaminergic mesolimbic and nigrostriatal systems in mediation of the motivational arousal and motor performance of an instrumental food response.

Animals↗
PubMed1987

Different types of nerve profile in the wall of the canine hepatic artery: an electron microscopic study.

The fine structure of the hepatic artery of dogs was studied at electron microscopic level. The majority of nerve fibres innervating the artery was found at the adventitial-medial border of the vessel, but some of them entered the middle part of the media. The average distance of nerve to muscle fibre was found to measure 450 nm. Three types of nerve profile could be observed, viz. adrenergic, cholinergic and cholinergic-peptidergic as suggested by the morphology of their vesicles. It is suggested that the cholinergic and cholinergic-peptidergic nerve endings probably modulate the release and the constrictor effect of the main neurotransmitter noradrenaline in the hepatic artery.

Adrenergic Fibers↗
PubMed1987

Pancreatic and intestinal growth-promoting effect of truncal vagotomy in the rat.

The effect of chronic subdiaphragmatic truncal vagotomy was investigated on body weight gain, food intake pattern, and also on intestinal and pancreatic growth, in adult rats. Two sham-operated groups, the one fed ad libitum, the other pair-fed with the vagotomized rats, served as controls. Body weight of vagotomized rats decreased in the first 5 postoperative days, due to hypophagia. Then, body weight increased as food intake reached the presurgery level. The rats were killed after 34 days of vagotomy. A moderate pancreatic and intestinal hypertrophy was observed in the vagotomized rats, while the tissue weight of and the DNA and protein contents in the colon and the oxyntic and antral areas of the stomach did not change compared to controls. The mechanism of the intestinal and pancreatic hypertrophy is unknown; several humoral and nervous factors may be involved in it.

Animals↗
PubMed1986

Motivational versus motor impairment after haloperidol injection or 6-OHDA lesions in the ventral tegmental area or substantia nigra in rats.

The effects of blockade of dopaminergic receptors as well as the lesions of dopaminergic neurons on the behaviour of rats in "motivational" and "motor" tests were examined. Both systemic injection of haloperidol and 6-OHDA lesions in the ventral tegmental area (VTA) or substantia nigra, pars compacta (SN/pC) induced a decrease in the number of wins made by thirsty animals fighting for water in a water competition test. The rats with lesions in the VTA became insensitive to motivational thirst stimuli. The reaction of rats lesioned in the SN/pC was still dependent on the level of thirst. Both groups did not differ from controls in the amount of water intake. In the rotating rod test the animals with destroyed nigrostriatal system showed a substantial motor impairment, while destruction of the mesolimbic system had no effect in that test. The role of dopaminergic systems in terms of their involvement in the control of motivational arousal and motor performance has been discussed.

Animals↗
PubMed1986

Vasoactive intestinal peptide may participate in the vasodilation of the dog hepatic artery.

The possible direct action of vasoactive intestinal peptide (VIP) on dog hepatic arterial wall or on the noradrenergic innervation of the artery was investigated in vitro. In addition, VIP-containing nerve fibers and terminals were located in the wall of the artery with immunochemical staining. Direct evidence showed that VIP did not affect the release of [3H]norepinephrine but reduced the response of the isolated hepatic artery to electrical field stimulation and exogenous norepinephrine. This suggests that the effect of VIP is postjunctional on the smooth muscle of the artery. VIP-containing nerve fibers and varicosities were observed in the adventitial and medial layer of the arterial wall. These findings strongly support the hypothesis that vasoactive intestinal peptide is a physiological mediator of vasodilation in the hepatic artery.

Animals↗
PubMed1985

Inhibition of pancreatic secretory and trophic response to caerulein by the H2-receptor antagonist ranitidine in the rat.

The effect of ranitidine (20 mg . kg-1) and cimetidine (50 mg . kg-1) on pancreatic secretory and trophic responses to caerulein (1 microgram . kg-1) was studied in the rat. Ranitidine or cimetidine were administered alone or combined with caerulein twice a day for 7 days. Saline-treated rats were used as controls. At the end of treatment animals were anesthetized and pancreatic juice was collected for 1 h after intravenous secretin plus CCK-PZ (8 U . kg-1). Afterwards rats were sacrificed and growth and composition of pancreatic tissue were determined. Compared with control (saline) values, volume of pancreatic juice and output of trypsin and amylase were increased by treatment with caerulein. Ranitidine, when given combined with caerulein, completely abolished the secretory response induced by the peptide, whereas it was totally ineffective when given alone. Cimetidine (alone or combined with caerulein) was always ineffective. Caerulein increased pancreatic weight, total pancreatic trypsin, amylase and RNA content. Here again ranitidine, combined with caerulein, abolished almost completely the trophic effect of caerulein on the pancreas, but when given alone it did not influence pancreatic growth and composition. Also in this case, cimetidine was completely inactive. These results suggest that ranitidine affects exocrine pancreas with an action independent of the H2-receptor blockade.

Amylases↗