Biomedical subjects

D M Denbow

Publications and source records attributed to D M Denbow.

114 records · Page 7Linked to original sources

PubMedDate not supplied

Eating, drinking and temperature responses to intracerebroventricular cholecystokinin in the chick.

The central effect of cholecystokinin-octapeptide (CCK), SQ 19,844 or sincalide, on the intake of food and water and on colonic temperature (Tc) was investigated using the broiler cockerel. Four-week old chicks were maintained in a thermoneutral environment of 23-24 degrees C. After food was removed for a 24 hr interval, CCK was infused in a volume of 10.0 microliters into the lateral cerebral ventricle (ICV) in doses ranging from 10-150 ng. Although lower doses of CCK had no effect on food intake, 100 or 150 ng of CCK significantly reduced consumption of food in a dose-dependent manner; water drinking was significantly decreased by 100 ng of CCK. In addition, CCK at doses of 100 and 150 ng prevented the slow rise in Tc observed following infusions of control CSF. This latter effect appeared to be a result of feeding activity associated with caloric intake and the heat increment in the control birds rather than a specific thermoregulatory effect. Overall, our results suggest that CCK may comprise a part of the central mechanism underlying the neural control of short term satiety in an avian species similar to that proposed for the mammal.

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PubMedDate not supplied

Feeding, drinking and temperature responses to intracerebroventricular beta-endorphin in the domestic fowl.

Four experiments were conducted to evaluate the effect of beta-endorphin (beta-END) on feeding, drinking and colonic temperature in rapidly growing (Rock-Cornish; RC) and slow growing (Single-Comb White Leghorn; SCWL) stocks of chickens. In the first experiment RC cockerels were injected intracerebroventricularly (ICV) with 0, 1.5, 3.0 and 6.0 micrograms of beta-END. In the second experiment RC cockerels were injected ICV with 0.5, 1.0 and 2.0 micrograms of beta-END. Experiments 3 and 4 were conducted identically to Experiment 1 and 2, respectively, except SCWL were used. Administration of beta-END at levels between 1.5 and 6.0 micrograms produced a significant curvilinear increase in feeding in both RC and SCWL chicks. In RC chicks, feeding was significantly elevated at 45 min and from 90 through 240 min postinjection, whereas in SCWL chicks feeding was increased from 90 through 300 min postinjection. Water intake was depressed in RC and SCWL from 60 through 90 min and from 30 through 60 min postinjection, respectively. Significant increases in water occurred at 180 and 300 min postinjection in SCWL. beta-END also induced a significant hyperthermia in RC and SCWL from 30 through 240 min and from 15 through 180 min postinjection, respectively. At low levels of beta-END, i.e., 0, 0.5, 1.0 and 2.0 micrograms, feeding, drinking and body temperature were significantly increased in both stocks. Feeding in RC chicks was stimulated in a linear fashion from 180 through 300 postinjection while feeding in SCWL was stimulated in a curvilinear manner from 180 through 240 min postinjection.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMedDate not supplied

Food intake, gastric secretion, and motility as affected by avian pancreatic polypeptide administered centrally in chickens.

The effects of intracerebroventricular (ICV) injections of avian pancreatic polypeptide (APP) on food intake, gizzard motility, gastric secretion volume, pH, and pepsin concentration was investigated using 16-20-week-old Single-Comb White Leghorn hens. Birds were stereotaxically cannulated in the right lateral ventricle. In addition, a strain gauge was attached to the gizzard to measure motility and a polyethylene cannula was implanted into the caudoventral margin of the proventriculus to collect glandular secretions. All birds were fasted for 18 hr prior to the injection of APP. In Experiment 1 food was made available immediately following the injection of APP while in Experiment 2 food was withheld for an additional one hr post-injection. The ICV injection of APP significantly increased food intake but had no significant effect on gizzard motility, gastric secretion volume, pH, or pepsin concentration in birds given access to food immediately after injection. In birds which remained fasted after injection, pepsin concentration was decreased by APP injection, but gizzard motility, gastric secretion volume, and pH were not affected. Because ICV injections of APP significantly increased food intake and, in fasted birds, decreased pepsin concentration, it appears that APP is involved in the central nervous system control of food intake and pepsin secretion in the domestic fowl.

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PubMedDate not supplied

Centrally and peripherally administered bombesin decreases food intake in turkeys.

The effects of intracerebroventricular (ICV) and intravenous injections of bombesin (BBS) on food intake were investigated in turkeys. Adult turkey hens were injected ICV with 50 to 1000 ng of BBS. In addition, the effect of pretreatment with the BBS antagonist [d-Arg1, D-Phe5, D-Trp7,9, Leu11]-substance P was investigated. To determine if BBS also had a peripheral site of action, 0.5 to 8 micrograms/kg body weight of BBS was injected IV into turkey poults. The ICV and IV injections of BBS decreased food and water intake in a dose-dependent manner. The most efficacious doses when injected ICV for decreasing food and water intake were 1000 and 500 ng, respectively, whereas 8 micrograms/kg was most efficacious in decreasing food intake when administered IV. The satiating effect of ICV-injected BBS could be attenuated with pretreatment with the BBS antagonist. The results of these studies suggest that BBS acts to decrease food and water intake in both the periphery and the central nervous systems of turkeys.

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PubMedDate not supplied

Differential cardiovascular effects of pharmacological agents in chickens selected for high and low body weight.

This study was conducted to investigate whether there are differences in the autonomic nervous system function of chickens from lines selected for high (HWS) or low body weight (LWS). The cardiovascular response to various pharmacological agents was used as an indicator of autonomic nervous system response. Ten individuals from each line and sex were used in the study. Catheters were introduced into the left brachial artery and vein and connected to a MP100-BIOPAC system to record blood pressure and heart rate (HR). Chickens were injected with phenylephrine, atropine, propranolol, and tetraethylammonium chloride (TEAC). The LWS birds exhibited a greater increase in mean arterial blood pressure (MABP) and a lesser increase in HR than the HWS birds following atropine. The response to atropine showed a line and sex interaction in which male birds had a greater increase in HR than females and LWS females had a lower increase in HR than the HWS females. Injection of phenylephrine following pretreatment with atropine caused a baroreceptor reflex in which males showed a greater decrease in HR than females. In response to the beta-adrenergic receptor blocker propranolol, females displayed a greater decrease in MABP than males and LWS birds had a greater decrease in HR than HWS birds. In response to the autonomic ganglionic blocker TEAC, MABP and HR decreased equally in both lines. The percentage of adrenal and sympathetic impact on regulation of HR showed that LWS females required greater adrenal activity than those from the other subclasses. Although changes in HR and MABP ratios in response to phenylephrine were different between lines, these responses were not different when phenylephrine was given following atropine. This pattern of response suggested that HWS birds had greater parasympathetic nervous system activity in order to maintain cardiovascular function. These results demonstrate that selection for HWS or LWS has resulted in greater parasympathetic and sympathetic nervous system tone in birds from the HWS and LWS birds, respectively, and suggest that differences between the lines could be at the level of the chromaffin tissue in the adrenal gland.

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PubMedDate not supplied

Intracerebroventricular injection of fusaric acid attenuates the anorexia by glucagon-like peptide-1 in the neonatal chick.

It is known that central injection of glucagon-like peptide-1 (GLP-1) suppresses feeding in rats and chicks, but the systems for GLP-1 are still open with special reference to the chick. The present study was done to determine whether a noradrenergic mechanism contributes to the anorexigenic effect of GLP-1 on the neonatal chick. Central administration of norepinephrine (NE) suppressed food intake with narcolepsy as GLP-1 in chicks. However, in spite of that dopamine (DA) did not affect food intake, coadministration of inhibitor of dopamine-beta-hydroxylase (DBH), fusaric acid (FA), attenuated the suppressive effect of GLP-1 on feeding behavior. It is suggested that there may be the interactive relationships between GLP-1 and noradrenergic system in the neonatal chick.

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