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F Kaya

Publications and source records attributed to F Kaya.

9 recordsLinked to original sources
PubMed2001

Effects of acid inhibition on somatostatin-producing cells in the rat gastric fundus.

Somatostatin plays a role in the regulation of gastric acid secretion. Omeprazole, a potent inhibitor of gastric acid secretion, has been reported to cause either a significant decrease or increase in the formation of gastric somatostatin-producing cells. Therefore, we determined in the present study distribution patterns of somatostatin mRNA and protein in fundus mucosa of rats after long-term inhibition of gastric acid secretion. Female Sprague-Dawley rats were given 0, 20 and 100 mg/kg/day omeprazole, respectively, as gastric instillations during 2 months. Serum gastrin levels were significantly higher in the third group than in the other groups. The omeprazole-treated groups also showed an increase in the number of somatostatin-containing cells in fundus mucosa. Moreover, the intensity of somatostatin-positivity was higher in the treated groups than in the control group. We also observed an increase in the number of cells containing somatostatin mRNA in fundus mucosa of omeprazole-treated rats. These results suggest that long-term inhibition of acid secretion does not inhibit but stimulate somatostatin production in mucosa of rat gastric fundus.

Animals↗
PubMed2001

Effect of 5-aminoimidazole-4-carboxamide riboside (AICA-r) on isolated thoracic aorta responses in streptozotocin-diabetic rats.

Diabetes mellitus alters the vascular responsiveness to several vasoconstrictors and vasodilators. 5-amino-4-imidazole-carboxamide riboside (AICA-r), a nucleoside corresponding to AICA-ribotide and an intermediate of the de novo pathway of purine biosynthesis, was recently proposed as a new insulinotropic tool in non-insulin-dependent diabetes mellitus. The aim of the present study was to define whether AICA-r affects altered vascular responsiveness to vasoconstrictors and vasodilators in the thoracic aorta of neonatal streptozotocin (STZ)-diabetic rats. The results of this study indicate that a 1-month treatment with AICA-r significantly increases the body weight in diabetic rats; significantly decreases the blood glucose level of diabetic rats (from 302+/-47 to 135+/-11 mg/dL, p<0.001); does not significantly affect the fast, slow, and total components of responses to noradrenaline in all the experimental groups; reverses the increased Emax values of noradrenaline in diabetic rats to near-control values; reverses the completely abolished responses of acetylcholine (pD2 and percent relaxation) in diabetic rats to control values; and reverses the decreased pD2 values of sodium nitroprussiate in diabetic rats to control values. In conclusion, AICA-r treatment in neonatal STZ-diabetic rats improved increased blood glucose levels, accelerated weight gain, reversed endothelial dysfunction, and normalized vascular responses.

Acetylcholine↗
PubMed2000

Influence of lignin and its degradation products on enzymatic hydrolysis of xylan.

The influence of lignin, lignin model compounds, and black liquor from the kraft pulping process on the hydrolysis of xylan by xylanase was investigated. Addition of vanillic acid, acetovanillone, and protocatechuic acid increased the rate of hydrolysis of xylan by as much as 18-50% at low concentrations, but reached maxima at about 0.05% concentration. Addition of vanillin caused a 15% improvement in xylan hydrolysis, while addition of guaiacol more than doubled the hydrolysis rate. Increasing concentrations of either lignin or black liquor also increased the hydrolysis rate of xylan. Circular dichroism spectroscopy indicated a change in the structure of xylanase in the presence of black liquor.

Biodegradation, Environmental↗
PubMed1994

Effects of dopamine receptor agonists on food intake and rumen motility in dwarf goats.

In ruminants, the dopaminergic regulation of feeding behaviour has not been investigated. Therefore, the effects of dopamine receptor agonists and antagonists on food intake and forestomach motility were studied in dwarf goats. Goats treated i.v. with bromocriptine (1 micrograms or 2.5 micrograms/kg body wt/min during 10 min) ate less food than when treated with saline. This inhibitory effect on food intake could not be prevented by the peripheral dopamine receptor antagonist domperidone (0.5 mg/kg body wt i.v.). In contrast, dopamine (i.v. 20 micrograms/kg body wt/min during 15 min), levodopa (i.v. 40 micrograms/kg body weight during 10 min), apomorphine (i.v. 2 micrograms/kg body wt/min during 10 min) and lisuride (i.v. 0.2 microgram/kg body wt/min during 15 min and 0.5 microgram/kg body wt during 10 min) failed to modify food intake. Given in association with benserazide, a decarboxylase inhibitor (i.v. 20 micrograms/kg body wt/min during 10 min), levodopa was still inactive as an anorectic agent. Levodopa, bromocriptine and lisuride administered at similar dose rates to those which were used in the food intake experiments, induced some clinical signs including inhibition of forestomach contractions. The inhibition of rumen contractions induced by these drugs was completely antagonized by domperidone pretreatment. These results, together with earlier in vivo and in vitro observations, suggest that the inhibitory effects of dopamine receptor agonists on forestomach contractions are due to interactions with peripheral dopaminergic receptors. The change in smooth muscle tension, which leads to a change in the signals transmitted via vagal afferents to the central nervous system, probably does not modify feeding behaviour in dwarf goats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Food intake and rumen motility in dwarf goats. Effects of some serotonin receptor agonists and antagonists.

The serotonergic regulation of feeding behaviour has not so far been studied in ruminants. Therefore, the effects of some serotonin (5-HT) receptor agonists and antagonists on food intake and forestomach motility were studied in dwarf goats. Goats ate less food when treated intravenously (IV) with the 5-HT precursor 5-HTP (25 micrograms, 50 micrograms or 100 micrograms kg-1 min-1 over 15 min) than when they were treated with 5-HT (which does not pass the blood-brain barrier) or with saline. Accordingly, IV dexfenfluramine infusions (50 micrograms or 100 micrograms kg-1 min-1 over 15 min), which induces release of brain 5-HT, also led to dose-related reductions in food intake. In contrast, no anorectic effects were observed after IV infusions with the selective 5-HT reuptake inhibitor fluoxetine (100 micrograms kg-1 min-1 over 15 min), the selective 5-HT1A agonist 8-OH-DPAT (0.5 micrograms kg-1 min-1 over 15 min), or eltoprazine (4 or 8 micrograms kg-1 min-1 over 15 min), a mixed 5-HT1A/5HT1B receptor agonist. None of the 5-HT antagonists tested gave any increase in food consumption in this model. Interestingly, the non-selective 5-HT receptor antagonist methysergide (360 micrograms/kg IV) reduced food intake. This effect was most noticeable at 3 h after injection. The 5-HT3 receptor antagonist ondansetron (IV 10 micrograms kg-1 min-1 over 15 min) and the peripheral 5-HT2 receptor antagonist xylamidine (IV 100 micrograms kg-1 min-1 over 10 min) failed to modify food intake. These results provide evidence for central serotonergic involvement in the control of feeding. However, this control system differs markedly in goats and rodents. Dexfenfluramine, 5-HTP and eltoprazine administered at similar dose rates to those used in the food intake experiments induced some clinical signs including inhibition of forestomach contractions. These results, together with our earlier in vivo and in vitro observations, suggest that the inhibitory effects of serotonin receptor agonists on forestomach contractions are due to interactions with both peripheral and central serotonergic receptors. The change in smooth muscle tension, which leads to a change in the signals transmitted via vagal afferents to the central nervous system, appears not to modify feeding behaviour in dwarf goats.

Animals↗
PubMed1992

Changes in food intake and forestomach motility of dwarf goats by recombinant bovine cytokines (IL-1 beta, IL-2) and IFN-gamma.

The present study was carried out to investigate the effects of rboIL-1 beta, rboIL-2, and rboIFN-gamma on food intake and forestomach motility in conscious dwarf goats. The intravenous injection of rboIL-1 beta (1 micrograms kg-1) resulted in tachycardia and an immediate fever that reached peak values 45 and 180 min after injection. At 9 to 13 min after rboIL-1 beta administration, both frequency and amplitude of rumen contractions rapidly diminished, being minimal at 30 min; during the fever, all goats refused to eat. Compared with the fever induced by rboIL-1 beta, that caused by rboIFN-gamma (2 micrograms kg-1 IV) was delayed in onset. Although the biphasic fever after rboIFN-gamma was more pronounced than after rboIL-1 beta, the changes in forestomach motility, food intake, and heart rate were less than after rboIL-1 beta. No changes in rectal temperature, heart rate, forestomach motility, and food intake were observed after rboIL-2 (1 micrograms kg-1 IV) injection. These results strongly indicate that the effects of cytokines on body temperature can be dissociated from their effects on food intake. Furthermore, these data suggest a possible relationship between forestomach motility and food intake.

Animals↗