Tomonori Nakanishi

Suppression of food intake induced by corticotropin-releasing factor family in neonatal chicks.

Corticotropin-releasing factor (CRF), urocortin and urotensin I share amino acid sequences, and they inhibit food intake in mammals. CRF plays a potent role in decreasing food intake in avian species, but the effects of urocortin and urotensin I have not been investigated. Therefore, the effect of these three peptides on food intake in the neonatal chick was compared. In Experiment 1, birds were injected intracerebroventricularly (i.c.v.) with either 0, 0.01, 0.1 or 1 microg of urocortin following a 3-h fast, and food intake was measured for 2 h post-injection. Food intake was suppressed in a dose-dependent manner. Using a similar design in Experiment 2, the effect of urotensin I was investigated. Urotensin I appeared to suppress food intake in neonatal chicks more than urocortin did. In Experiment 3, the efficacy of CRF, urocortin and urotensin I was directly compared using one dose, 0.1 microg. The results indicated that the suppressive effect on food intake was strongest for CRF followed by urotensin I, then urocortin. These results suggest that the structure of receptors for the CRF family in chicks may be somewhat different than in mammals.

Effect of Garcinia cambogia extract on serum leptin and insulin in mice.

In this study we examined the effects of 3.3% Garcinia cambogia extract on 10% sucrose loading in mice for 4 weeks. Treatment was found to have no effect on body weight, fat pad weight or serum glucose level. On the other hand, serum total cholesterol, triglycerides, NEFA were observed. Levels of serum insulin and leptin, as well as the leptin/WAT ratio, were lower in the treated mice than in the control. These findings suggested that G. cambogia extract efficiently improved glucose metabolism and displayed leptin-like activity.

Effect of central administration of prolactin-releasing peptide on feeding in chicks

Prolactin-releasing peptide (PrRP) is one of the inhibitory factors in feeding regulation of mammals. However, no information is available for avian species. The present study was done to clarify the effect of intracerebroventricular (ICV) injection of PrRP on feeding in chicks. Firstly, we found that ICV injection of PrRP (94-1500 pmol) significantly increased food intake in chicks. The result was completely different from those obtained in mammals. The orexigenic effect of PrRP was significantly weaker than that of neuropeptide Y (NPY), a potent orexigenic peptide, on an equimolar basis. The orexigenic effect of NPY was further enhanced with coinjection of PrRP. These results suggest the existence of a novel orexigenic mechanism in the chick brain, which might differ from NPY-involved feeding regulatory pathway. In addition, ICV injection of PrRP significantly decreased the rectal temperature, but the effect was weaker than that of NPY, suggesting that PrRP may inhibit energy expenditure in chicks. Taken together, we showed here that PrRP may be involved in the regulation of both feeding behavior and energy metabolism in the chick brain.

Interaction of corticotropin-releasing factor and glucagon-like peptide-1 on behaviors in chicks.

Both corticortropin-releasing factor (CRF) and glucagon-like peptide-1 (GLP-1) inhibit food intake of chicks, but they also produce other behaviors. The present experiments were undertaken to clarify the interaction of CRF and GLP-1 regarding their anorectic actions as well as other behaviors. In Experiment 1, birds were injected intracerebroventricularly (i.c.v.), following a 3-h fast, with either saline, 0.1 microg of CRF, 0.1 microg of CRF+0.1 microg of GLP-1 or 0.1 microg of CRF+1 microg of GLP-1, and food intake was measured for 2 h. The injection of CRF decreased food intake, and CRF injected with GLP-1 suppressed food intake for up to 2 h. Birds were treated similarly in Experiment 2 in which the doses of CRF and GLP-1 were reversed. GLP-1 strongly suppressed food intake, and this effect was augmented by coadministration of CRF. In Experiment 3, the behaviors of chicks injected with saline, CRF (0.1 microg), GLP-1 (0.1 microg) or CRF (0.1 microg)+GLP-1 (0.1 microg) were monitored for the numbers of steps, vocalization and locomotion. Chicks were excited, moved more and vocalized loudly following injection of CRF, whereas an opposite response was seen with GLP-1. The behaviors were intermediate following the coinjection of the two peptides. In conclusion, CRF and GLP-1 interact in the chick brain, but the response depends on the behavior being measured.

Dietary conjugated linoleic acid reduces cerebral prostaglandin E2 in mice

Abstract Conjugated linoleic acids (CLA) are naturally occurring fatty acids that have been recognized to modify prostaglandin (PG) production in specific tissues. So far, no relationship between PG production and CLA has been reported in the brain. Thus, the effects of CLA on cerebral prostaglandin E 2 (PGE 2 ) levels and cyclooxygenase (COX)-1 and COX-2 mRNA expression in mice were determined in the present study. Mice given the diet with or without 3% CLA at the age of 9 weeks were mated, reproduced and lactated. Offspring mice given each diet until 25 days and 8 weeks of age were sacrificed and their brains removed. Production of PGE 2 was reduced while COX mRNA was quantitatively increased by CLA supplementation. These results imply that brain PGE 2 production can be reduced by dietary CLA without inhibition of COX gene expression in mice.

Ghrelin Activates Behavior of Neonatal Chicks in a Short Period of Post-Intracerebroventricular Injection

Abstract Saito, E., Takagi, T., Nakanishi, T., Sashihara, K. and Furuse, M. 2002. Ghrelin activates behavior of neonatal chicks in a short period of post-intracerebroventricular injection. J. Appl. Anim. Res., 22: 33–41. Ghrelin, a novel growth hormone (GH)-releasing peptide with an acylated side chain, is the endogenous ligand for the GH secretagogue receptor. Intracerebroventricular (ICV) injection of ghrelin stimulates GH secretion and feeding of rats, but ghrelin inhibited feeding of neonatal chicks. It was also confirmed that ghrelin induced sleep-like behavior later than 30 minutes post-administration in neonatal chicks. However, exciting behavior was observed in a short period (less than 30 min) in previous reports. Thus, we further investigated the behavioral changes in neonatal chicks by ICV administration of ghrelin within a short period. Chicks were divided into two groups and administered ICV saline or 2μg of ghrelin and the numbers of step and vocalization were monitored. Just after behavioral test, the amount of monoamines of chick hypothalamus was determined by high performance liquid chromatography. Central ghrelin enhanced the numbers of step and kept the numbers of vocalization, but no significant difference in the amount of monoamines was detected. In conclusion, central ghrelin activates chick behavior in a short period without modification of hypothalamic monoamine contents.

Effect of Orally Administered Conjugated Linoleic Acids on Behaviors and Tissue Fatty Acid Compositions in Mice

Abstract Nakanishi, T., Ohgushi, A., Yamashita, T., Sashihara, K., Takagi, T., Dobashi, E., Kamegai, T., Kasai, M., Yoshimatsu, T. and Furuse, M. 2001. Effect of orally administered conjugated linoleic acids on behaviors and tissue fatty acid compositions in mice. J. Appl. Anim. Res., 20: 157–170. To compare the influences of the oral administration of conjugated linoleic acids (CLA) on behaviors and fatty acid composition of some tissues with those of linoleic acid, (LA) and docosahexaenoic acid (DHA), mice (8-week old) were orally administered with oils containing high levels of CLA DHA or LA for 4 weeks (6 days per week, 0.2 ml per day). Control, group was administered with saline. Behavioral tests such as locomotor activity swim test elevated plus maze lest and biting test, were done on the commencement of the study (0 week) and 2 and 4 weeks after treatments. No significant changes were observed in, all the parameters. Oral. CLA increased the liver weight and reduced the epididymal, white adipose tissue weight. The ratio of arachidonic acid to total, fatty acids was significantly increased by LA and decreased, by CLA compared with the control, especially in the liver. Small amounts of CLA were detected in the brain of mice administered with CLA or LA groups, but, not detected, in mice of the control and DHA groups. The level of DHA in the brain was not altered by DHA administration. It is concluded that oral administration of CLA influenced some tissues but not behaviours of mice at least after growth.

Dietary CLA and DHA modify skin properties in mice

This study investigated the influence of PUFA on the properties of mouse skin. Mice (3 wk old) were given free access to oils high in linoleic acid, CLA, or DHA for 4 wk. At the end of the experiment, their skins were compared by both biochemical and histological methods. No significant differences in lipid and collagen contents were detected among treatments, although the FA composition in the skin was altered depending upon the FA composition of the supplemented oils. Electron microscopy revealed that the subcutaneous tissue layers in the CLA and DHA groups were significantly thinner than that in the high linoleic acid group, whereas no differences in the thickness of dermis layers were observed among the three groups. These results suggest that skin properties in mice are readily modified by dietary FA sources within 4 wk of dietary oil supplementation.

Modification of skin composition by conjugated linoleic acid alone or with combination of other fatty acids in mice.

The effects of conjugated linoleic acid (CLA), gamma-linolenic acid (GLA), linoleic acid (LA), and their combinations, on skin composition in mice were investigated. Mice (8 weeks old) were orally administered with either LA, GLA, CLA, LA + GLA, LA + CLA, or CLA + GLA for 4 weeks. Then, the skin was analysed for triacylglycerol content, fatty acid composition and collagen content. Additionally, thicknesses of the dermis layer and subcutaneous tissue layer, and the size and number of adipocytes were measured histologically. The skin fatty acid composition was modified depending upon the fatty acid composition of supplemented oils. In each oil-alone group, skin triacylglycerol content was the highest in LA, followed by GLA and CLA treatments. Combinations with CLA had a similar triacylglycerol content compared with the CLA-alone group. No significant changes in collagen content were observed among any treatments. The effects on subcutaneous thickness were similar to the results obtained in the triacylglycerol contents, where groups supplemented with CLA alone or other fatty acids had significantly thinner subcutaneous tissue compared with the LA-alone group. However, no significant difference was detected in the thickness of the dermis layers. The number of adipocytes was highest in the LA + GLA group and tended to be reduced by CLA with or without the other fatty acids. These results suggest that CLA alone or in combination with other fatty acids strongly modifies skin composition in mice.

Alpha-helical CRF9–41, Blocks Stress- and CRF-induced Behavior Changes in Chicks

Abstract Zhang, R., Ohgushi, A., Takagi, T., Nakanishi, T., Saito, E.-S., Yoshimatsu, T., Denbow, D.M. and Furuse, M. 2002. Alpha-helical CRF9–41, blocks stress- and CRF-induced behavior changes in chicks. J. Appl. Anim. Res., 22: 169–176. Three experiments were conducted, to test the role of the brain corticotropin-releasing factor (CRF) system in mediating stress-induced behaviors and regulating food intake by using CRF receptor antagonists (α-helical CRF9–41 and astressin) in chicks. In Experiment 1, birds were intracerebro-ventricularly (i.c.v.) injected with 10 fig of a-helical CRF9–41 or saline and placed individually into an acrylic glass recording chamber 20 min post-injection and automatically monitored by an audio analysis application for 60 seconds. The number of distress vocalizations (DVs) induced by isolation was significantly suppressed by α-helical CRF9–41 compared to the control group. Chicks were similarly treated with astressin in doses of 0, 5 and 10 fig in Experiment 2, but no significant difference of DVs was observed. In Experiment 3, after a 3h fast, birds were i.c.v. injected with either saline, 0.1 μg of CRF, 0.1 μg of CRF + 5 μg of α-helical CRF9–41 or 0.1 μg of CRF + 10 μg of α-helical CRF9–41 and food intake was measured for 2h. CRF suppressed food intake and α-helical CRF9–41 partially blocked such effect. The results suggested that 1) α-helical CRF9–41 attenuated the behavior changes induced by isolation and exogenous CRF; 2) CRF receptors in avian species may be somewhat different from that in mammals.