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Biomedical subjects

C L McLaughlin

Publications and source records attributed to C L McLaughlin.

At least 55 records · Page 3Linked to original sources
PubMed1983

Food intake response to modulation of secretion of cholecystokinin in Zucker rats.

Exogenous administration of cholecystokinin (CCK) decreases food intake and elicits satiety behaviors. In the present experiments, feeding behaviors of Zucker obese and lean rats were measured in response to treatments that influence endogenous secretion of CCK from the duodenum. Secretion of CCK was increased by administration of phenylalanine, a stimulant of CCK release, and of trypsin inhibitor, which binds to trypsin, a negative-feedback signal for CCK release. Both of these treatments decreased the size of the first meal after a 6-h fast and average daily meal size and increased meal frequency. Administration of trypsin, proported to decrease secretion of CCK, increased average daily meal size and decreased meal frequency. Pancrease, a pancreatic enzyme concentrate, also hypothesized to act as a negative-feedback signal for CCK release, elicited feeding behaviors similar to those of trypsin. Thus the effects of these compounds on the feeding behavior of Zucker obese and lean rats may be related to their effects on CCK secretion. The feeding behaviors of obese rats were affected less than those of lean rats by exogenous administration of CCK, but in these experiments were affected more than in lean rats by modulation of endogenous release of CCK.

Animals↗
PubMed1983

Preferred flavors and performance of weanling pigs.

To characterize the flavor preferences of weanling pigs, a T-maze test was designed and validated. After having sampled feed from one side, containing flavor, and the other side, containing no flavor, pigs were allowed to select feed from either side of the T-maze five times. The frequency of selecting the flavored feed and the percentage of total feed eaten in 20 s/run were used to establish degree of preference for flavors. A total of 129 flavors or flavor combinations was tested in 248 trials, with some flavors tested at several concentrations. At least four flavors were tested in each of eight major flavor groups; the frequency distribution of preference did not differ among groups. Five specific flavors, highly preferred by the pigs in the T-maze tests, were selected for sustained preference tests for two 5-d periods. In the tests, a preference was shown for three of the five flavors. Two flavors were then tested for effects on performance using three groups of 10 pigs for 5 wk after weaning. The feed intakes and body weight gains were increased during the first week in both groups fed flavored feed compared with those of the control group. In a growth trial with 1,219 pigs, one of the two flavors increased feed intake and improved weight gain during the first week after weaning. Thus, although pigs did not appear to prefer flavors in any one of the groups tested, they did prefer specific flavors, which, when added to feed, improved feed intake and weight gain during the critical first week after weaning.

Animals↗
PubMed1983

Performance and carcass quality of swine injected daily with bacterially-synthesized human growth hormone.

In this study, growth rate, feed intake, feed efficiency and carcass quality were measured in pigs (24 barrows and 24 gilts, initial body weight = 23.0 +/- 4 kg) administered 0, .015, .030 or .060 mg/kg/day bacterially produced human growth hormone (hGH) until slaughter weight of 90 kg. Administration of hGH on the first treatment day resulted in a dose-dependent peak in serum concentration after 2 hrs and concentrations gradually returned to baseline by 22 hrs after treatment. Measurement of glucose, insulin and glucagon on the first and last days of treatment showed variable effects of treatment. In pigs treated with .015 mg/kg/day hGH average daily weight gain (.89 vs .82 kg, p less than .05) and feed intake (4.59 vs 4.25 kg, p less than .006) were increased, while feed efficiencies were not different among groups. The carcass data did not show consistent differences to indicate a hGH growth response. It is concluded that hGH may be effective in pigs for improving growth rate and at doses lower than those shown effective for porcine GH.

Animals↗
PubMed1982

Decreased pancreatic exocrine response to cholecystokinin in Zucker obese rats.

Cholecystokinin (CCK), one of the peptides secreted by the gastrointestinal tract during a meal, stimulates release of enzymes into pancreatic juice and is a trophic hormone for the pancreas. Administration of CCK also decreases food intake, and obese rats have been shown to have a higher threshold than lean rats for this apparent effect on satiety. In this study experiments were designed to compare the sensitivity of obese and lean rats to the effects of CCK octapeptide (CCK-8) on pancreatic structure and exocrine function. In both growing and adult Zucker rats DNA content of the pancreas from obese rats was decreased compared with that from lean rats [2.42 +/- 0.21 vs. 3.07 +/- 0.18 mg (P less than 0.01) and 2.46 +/- 0.25 vs. 3.01 +/- 0.19 mg (P less than 0.05), respectively], and in adult obese rats this was accompanied by decreased pancreas size on both absolute weight and percent of body weight bases. In adult obese Bar Harbor mice, although DNA content of the pancreas was also decreased [1.70 +/- 0.10 vs. 2.41 +/- 0.11 mg (P less than 0.01)], pancreas weight was not different (0.30 +/- 0.01 vs. 0.32 +/- 0.01 g). In young rats growth of the pancreas was stimulated by 2 micrograms/kg CCK-8 administered subcutaneously or 100 mg/kg of a trypsin inhibitor administered orally twice daily for 2 wk. Although both treatments increased weight and DNA and protein content of the pancreas, the increases in DNA and protein content were smaller in obese than lean rats, indicating a decreased responsiveness to both trophic agents. Administration of CCK-8 stimulated smaller increases in pancreatic juice volume and amylase release in obese compared with lean rats, indicating decreased pancreatic exocrine function in response to CCK. In adults the CCK-8 dose-response curve for amylase release from dispersed pancreatic acini of obese rats was similar to that of lean rats, indicating normal sensitivity in vitro. Thus, in obese rats and mice DNA content of the pancreas is decreased when compared with that of lean rats and mice, and this is accompanied by decreased in vivo responses to CCK in obese rats.

Animals↗
PubMed1982

Role of peptides from gastrointestinal cells in food intake regulation.

Many peptides are contained in specific cells distributed throughout the gastrointestinal tract. Some are known to be released by the presence of specific components of food and to affect specific gastrointestinal functions related to digestion and absorption of nutrients. For many of the more recently identified peptides, however, stimuli for release and physiological functions are unknown. Improved radioimmunoassay techniques have allowed measurement of serum concentration changes of peptides that act via endocrine but not neurocrine or paracrine modes of action. Peptides that may play a role in the control of food intake include cholecystokinin (CCK), bombesin (BBS) and pancreatic polypeptide (PP) as possible satiety components and opiates as possible hunger components. All four have been found in the brain as well as in the gastrointestinal tract. Systemic administration of each has been shown to affect food intake, but whether doses used produced changes that normally occur during a meal awaits further development of radioimmunological assays. In the obese, the decreased sensitivities to, or decreased concentrations of the satiety components CCK, BBS and PP and the increased concentrations of the hunger component, B-endorphin, may contribute to the imbalance of food intake and energy expenditure, which leads to the accumulation of adipose tissue.

Animals↗
PubMed1982

Effects of monensin fed to replacement dairy heifers during the growing and gestation period upon growth, reproduction, and subsequent lactation.

Sixty Holstein heifers initially weighing 196 kg were assigned by weight to treatments of 0, 200, and 600 mg of monensin. These treatments were fed daily until calving to determine effects of monensin on growth rate, feed consumption, feed efficiency, reproductive performance, and subsequent lactation. Throughout the feeding period the control (0 mg) heifers received sufficient feed to allow a calculated growth rate of .68 kg/day. Monensin treatment groups were fed the same amount of the identical ration over the 448-day experiment. Daily gain, feed intake, and feed efficiency for the 0, 200, and 600 mg treatments were .60, .69, .69 kg, 7.47, 7.46, 7.43 kg, and 12.41, 10.81, 10.81. Although days on trial to first estrus were not different among treatment groups, heifers fed monensin at 200 and 600 mg/day conceived 38 and 34 days sooner than 0 mg heifers. Percent conception, number of calves born, calf birth weight, and calving difficulty were not affected by treatment. Milk production was measured for 120 days subsequent to the experimental feeding of monensin. During this period heifers were fed a common ration ad libitum. Milk production of 17.1, 16.9, and 17.0 kg/day for 0, 200, and 600 mg was not affected by prior treatment.

Animals↗
PubMed1981

Effects of starvation and obesity on somatostatin, insulin, and glucagon release from an isolated perfused organ system.

We have studied the effects of starvation and of obesity on somatostatin, insulin, and glucagon release from an isolated perfused organ system in fed and 3- and 5-day fasted Holtzman rats and in obese (fa/fa) and lean (Fa/?) Zucker rats. Fasting for 3 days significantly decreased basal (-71%) and amino acid-stimulated (-62%) somatostatin output. After 5 days of starvation, there was a significant increase over the 3-day level in somatostatin output stimulated by amino acid plus glucose (+540%) and by amino acids plus tolbutamide (+238%). Three and five days of starvation severely depressed insulin output while having no statistically significant effects on glucagon secretion. Somatostatin output from obese Zucker rats was significantly greater than that from lean controls in response to amino acids (41.2 +/- 13.2 vs. 16.3 +/- 10.3 ng/25 min, P less than 0.05). Insulin output was greatly increased from obese compared to lean Zucker rats, whereas there were no statistically significant differences in glucagon output. These data show that fasting decreases and obesity increases both somatostatin and insulin release. They suggest that altered stimulation by nutrients was primarily responsible for changes in somatostatin and insulin release observed in starving and obese rats.

Amino Acids↗
PubMed1979

Cannabinols and feeding in sheep.

Marijuana, long used for the euphoria which results, recently has been found to stimulate hunger in humans but in several laboratory animals cannabinoids decrease food intake. Sheep, relatively more sensitive to chemicals that affect food intake, were injected IV with the d-and l-isomers of tetrahydrocannabinol and with a 9-aza-cannabinol) 9-AC) (8-(1,2-dimethylheptyl)-5,5-dimethyl-5H-[1]benzopyranol[3,4]pyridin-10-01, HCL) and feeding behavior was monitored. In the first 30 min, food intake was increased by the l-isomer and by 9-AC but not affected by d-delta 9-THC. After 24 h, feed intake was decreased by at least one dose of d-and l-delta 9-THC and 9-AC. The l-but not d-isomer was active at very low doses compared with doses used in many laboratory animals.

Animals↗