Effect of neuropeptide S receptor antagonists and partial agonists on palatable food consumption in the rat

Neuropeptide S (NPS) is the endogenous ligand for the previously orphan G-protein-coupled-receptor, now termed NPS receptor (NPSR). NPS has both anxiolytic and pro-arousal properties and decreases food intake. In this work we use a rat model of palatable food intake to test in vivo different analogs of human NPS developed in our laboratories and characterized in previous in vitro experiments as partial agonists ([Ala³]NPS and [Aib⁵]NPS), or antagonists ([d-Cys(^tBu)⁵]NPS and [^tBu-d-Gly⁵]NPS). Our results confirmed that intracerebroventricular (ICV) injection of NPS (1 nmol) decreases standard chow intake in food restricted rats as well as in freely feeding animals fed with standard or palatable food diets. [Aib⁵]NPS (30 and 60 nmol), like NPS, reduced palatable food intake, thus confirming in vivo its ability to activate NPSR. [Ala³]NPS (60 nmol) did not affect palatable food intake per se but blocked the anorectic effect of NPS, thus suggesting its ability to function as an antagonist in this model. Finally, [d-Cys(^tBu)⁵]NPS (20-60 nmol) and [^tBu-d-Gly⁵]NPS (10-30 nmol), described in previous in vitro studies as pure NPSR antagonists, did not affect palatable food intake when given alone, but fully blocked the anorectic effect of NPS. These results provide an important characterization of the pharmacological properties of these NPS analogs in vivo. Of particular relevance are the data showing that [d-Cys(^tBu)⁵]NPS and [^tBu-d-Gly⁵]NPS behave as pure antagonists at NPSR regulating food intake, indicating that these molecules are suitable tools for further investigation of the physiopharmacology of the NPS/NPSR system.     

Early weaning programs rats to have a dietary preference for fat and palatable foods in adulthood

The objective of this work was to study the effect of early weaning on alimentary preference for the macronutrients protein, carbohydrate and fat in adult rats. Male Wistar rat pups were weaned by separation from the mother at 15 (D15) or 30 (D30) days old. Body weight and food intake were measured every 30 days until pups were 150 days old. At 110 days of age, the alimentary preference was evaluated for 1 h on 3 consecutive days. At 120 days of age, the palatable diet test was conducted during 3 consecutive 24-h periods. Body weight and food intake were not altered, but early weaning in rats induced an alimentary preference to fat and hyperphagia of a palatable diet. In conclusion, early weaning, although did not modify body weight or basal food intake, promoted an increased preference for palatable and fatty foods. This demonstrates that early weaning is not capable of promoting perceptible alterations of alimentary behavior under normal laboratory conditions. However, in the presence of a stimulating factor such as a choice of nutrients or a palatable diet, a possible latent effect on dietary preferences may become apparent. Over the long term, this preference for foods with high caloric density can lead to obesity and metabolic perturbations.     

Dopamine Signaling in the Suprachiasmatic Nucleus Enables Weight Gain Associated with Hedonic Feeding

1. Download : Download high-res image (240KB)
2. Download : Download full-size image

     

Orexins在雌性大鼠条件性蔗糖摄取中的作用研究

目的:探讨Orexins在雌性大鼠的摄取蔗糖的操作反应行为的作用,以及在线索诱导下恢复寻找蔗糖行为中的作用。方法:将雌性SD大鼠分为限制进食组和自由进食组,以固定比率和累进比率训练大鼠自己摄取蔗糖颗粒。通过Ox R1受体拮抗剂SB-334867预处理,观察SB-334867对大鼠按固定比率摄取蔗糖行为和在线索诱导下恢复寻找蔗糖行为的影响。结果:限制进食的大鼠表现出按压有效杠杆次数和获取蔗糖颗粒数显著增多(P0.05),按压无效杠杆次数稍微增多。SB-334867可显著减少限制进食大鼠按压有效杠杆次数(P0.05)。与对照组相比,SB-334867在消退期间可显著增加按压有效杠杆的次数(P0.05);在恢复期间,限制进食大鼠按压有效杠杆的次数显著增多(P0.05)。结论:Orexins系统在大鼠条件刺激诱导摄取蔗糖中可能存在性别差异。     

Nutritional effects of supplementary diets on brood development,biological activities and honey production of Apis mellifera L

The present research work was conducted to assess the impact of nutrient-enriched diet on the physiological activities and subsequently honey yield. Eighteen colonies of Apis mellifera L. were selected from Dera Ismail Khan region, KPK, Pakistan, during the winter and summer seasons, 2019–2020. Five pollen supplement diets were prepared and provided to screen out the palatable one to be fed as pollen alternative nutrition to bee bread. Results of diet consumption regarding mean data for consumption rate displayed that soybean flour enriched artificial diet was maximally consumed (74.34 g) by honey bees per week. Minimum consumption was observed for grinded groundnut enriched diet (64.62 g) which was relatively lesser than the other tested artificial diets. Results of area of worker brood disclosed that soybean flour fortified diet (1489.27 cm²/colony) statistically noteworthy than the other artificial diets whereas control (463.51 cm²/colony) was least effective. Highest bee strength (10.00 bee frames/colony) was noted in the bee colonies fed with soybean flour fortified diet, date paste (8.0 bee frames/colony) was the next effective one, among the tested pollen replacement diets whereas relatively least (5 bee frames/colony) was noticed in case of grinded groundnut. Highest body weight (12.41 g) of neonate bees was noted in case of soybean enriched diet while lowermost (5.31 g) was noted in control bees. Results of wax cell built up and foraging efficiency were also superior in artificial diets than respective control bees. Hence, artificial diets especially soybean-enriched pollen alternative diet can boost up the physiology of honey bee leading to increased honey yield and profit.     

Effects of cessation of grazing on leaf‐level photosynthesis of Periploca laevigata

Abstract. The impact of grazing pressure on gas exchange of Periploca laevigata was studied in relation to its nutritional status. P. laevigata, a woody and highly palatable shrub, is an important forage species in the dry season in Cabo de Gata Natural Park (Almeria, SE Spain) where this study was carried out. Seasonal and diurnal courses of net photosynthesis, transpiration and stomatal conductance were measured in the field. In addition, soil and plant nutrient status were measured as potential factors influencing leaf photosynthetic levels. Early in the growing season, ungrazed P. laevigata had higher photosynthetic activity than grazed plants suggesting that the defoliated plants were still recovering from herbivore damage in the previous summer. Later in the growing season grazed P. laevigata had higher photosynthetic activity than ungrazed plants, suggesting higher metabolic activity and a possible investment in chemical defences. Concentrations of P and N in the soil were higher in the grazed area. The nutrient concentration of the leaves of P. laevigata was similar in grazed and ungrazed plants.     

Contrasting effects of herbivory on plant size and reproductive performance in two populations of the Critically Endangered species,Euphorbia clivicola R. A. Dyer

Euphorbia clivicola R.A. Dyer is a Critically Endangered Northern Province endemic confined to two populations that have declined drastically over the last decade. One population is protected within a Nature Reserve, while the other occurs in a peri-urban area. In order to determine the causes of the population declines, herbivory damage to plants in both the protected and urban populations was quantified and the effects of herbivory on various aspects of the population biology were assessed. Mountain reedbuck are believed to have been responsible for the herbivory in the protected population. Herbivory on the above-ground branches probably caused the small sizes of protected plants. These were on average less than half the size of urban plants. Herbivory caused a reduction in the number of flowers and fruit produced per protected plant and may have prevented the maturation of flowers into fruit, thereby reducing the total regenerative output of the population. An eight-year absence of fire had resulted in the build-up of a dense moribund grass layer. The selection of E. clivicola plants by mountain reedbuck may therefore have been due to their relatively high nutritional value and accessibility in the thick moribund grass layer. Fencing off the population to prevent entry of herbivores, and implementing a more suitable fire management programme is recommended, as is the adoption of a new IUCN status for the species of Critically Endangered (CR A1).     

Competitive interactions between palatable and unpalatable grasses native to a temperate semi-arid grassland of Argentina

The argument that selective grazing leads to competitive replacement of palatable grasses by unpalatable grasses is based upon the assumption that the competitive ability of the palatable species is higher than the one of unpalatable species in the absence of grazing. In order to test this hypothesis we have compared the competitive ability of Stipa clarazii (palatable) and S. trichotoma (unpalatable) under field conditions, and S. clarazii and S. gynerioides (unpalatable) under greenhouse conditions. The three species are native to a temperate semi-arid grassland of central Argentina. In the field experiment, plants of both species were grown either independently or in pairs (palatable + unpalatable), protected from grazing. Shoot and seed production were measured at the end of the growing seasons of 1993, 1994 and 1995. In the greenhouse experiment, plants of both species were grown in pots, either in monoculture or in mixture, under conditions of high and low water and mineral nutrient availability. Total biomass and seed production were measured at the end of the experimental period. In both experiments the presence of the unpalatable species did not affect (P < 0.05) the productive responses of the palatable species. On the contrary, the presence of the palatable species significantly reduced (P < 0.05) the productive responses of the unpalatable species. Our results support the assumption, on which most interpretations of floristic changes induced by grazing are based, that the competitive ability of palatable grasses is higher than the one of unpalatable grasses in the absence of grazing.