Behavioral and physiological effects of photoperiod-induced migratory state and leptin on a migratory bird, Zonotrichia albicollis: I. Anorectic effects of leptin administration

The hormone leptin is involved in the regulation of energy balance in mammals, mainly by reducing food intake and body adiposity and increasing energy expenditure. During energetically demanding periods, leptin’s action is often altered to facilitate fat deposition and maintain high rates of food intake. Despite the present controversy over the existence of an avian leptin, there is evidence that a leptin receptor exists in birds and its activation influences energy intake and metabolism. However, it is unknown whether the effects of the activation of leptin receptor on energy balance are modulated during migration. We manipulated photoperiod to induce migratory behavior in captive white-throated sparrows (Zonotrichia albicollis) and injected migratory and wintering sparrows with either murine leptin or PBS for 7 days. We measured food intake, changes in body composition and foraging behavior to test if leptin’s effects are altered during migratory state. Leptin decreased foraging behavior, food intake and fat mass in wintering sparrows, but had no effect on foraging behavior or food intake in migratory sparrows. Migratory sparrows injected with leptin maintained fat better than sparrows injected with PBS. Thus, sparrows’ responses to leptin changed with migratory state, possibly to aid in the increase and maintenance of rates of food intake and fat deposition. We also found that long-form leptin receptor and SOCS3 were expressed in tissues of sparrows, including the hypothalamus, but their expression did not change with migratory state. Further study of the leptin receptor system and other regulators of energy balance in migratory birds will increase our understanding of the physiological mechanisms that are responsible for their ability to complete energetically demanding journeys.     

Maternal high-fat diet in mice programs emotional behavior in adulthood

The maternal environment has a significant role in the normal development of the fetus and may have long-term impact on brain development including critical central pathways such as the gamma-aminobutyric acid (GABA), serotonergic and the neurotrophin systems. For example, maternal malnutrition plays an important role in programming many aspects of physiology and behavior including predisposition to mental-health related disorders such as anxiety. Here we investigated the effects of maternal high-fat diet or control diet for nine weeks (prior to gestation, gestation and lactation) on the adult offspring with respect to anxiety related behaviors as well as exploration and conditioned fear response. We found that offspring born to high-fat diet mothers showed increased anxiety-like behaviors, but intact conditioned fear response and exploratory behavior. In addition, brain-derived neurotrophic factor (BDNF) was significantly increased in the dorsal hippocampus, while GABA(A) alpha2 receptor subunit and 5-hydroxytryptamine 1A (5-HT1A) receptor showed increased levels in the ventral hippocampus. In summary, these findings suggest that maternal high-fat diet consumption during critical periods in the development of the fetus, might increase the risk of abnormal behaviors in adulthood related to anxiety.     

Online social networking and addiction--a review of the psychological literature

Social Networking Sites (SNSs) are virtual communities where users can create individual public profiles, interact with real-life friends, and meet other people based on shared interests. They are seen as a 'global consumer phenomenon' with an exponential rise in usage within the last few years. Anecdotal case study evidence suggests that 'addiction' to social networks on the Internet may be a potential mental health problem for some users. However, the contemporary scientific literature addressing the addictive qualities of social networks on the Internet is scarce. Therefore, this literature review is intended to provide empirical and conceptual insight into the emerging phenomenon of addiction to SNSs by: (1) outlining SNS usage patterns, (2) examining motivations for SNS usage, (3) examining personalities of SNS users, (4) examining negative consequences of SNS usage, (5) exploring potential SNS addiction, and (6) exploring SNS addiction specificity and comorbidity. The findings indicate that SNSs are predominantly used for social purposes, mostly related to the maintenance of established offline networks. Moreover, extraverts appear to use social networking sites for social enhancement, whereas introverts use it for social compensation, each of which appears to be related to greater usage, as does low conscientiousness and high narcissism. Negative correlates of SNS usage include the decrease in real life social community participation and academic achievement, as well as relationship problems, each of which may be indicative of potential addiction.     

Searching for Preclinical Models of Acute Decompensated Heart Failure: a Concise Narrative Overview and a Novel Swine Model

Cardiovascular Drugs and Therapy - Available animal models of acute heart failure (AHF) and their limitations are discussed herein. A novel and preclinically relevant porcine model of decompensated...