The hypothalamus is known to be important in the control of energy balance, including the regulation of body weight, food intake, and glucose homeostasis. The hypothalamic regulation of energy balance occurs through the actions of both classical neurotransmitters (such as norepinephrine, dopamine, and serotonin) and neuropeptides (including neuropeptide Y, galanin, enkephalin, growth hormone-releasing factor, somatostatin, beta-endorphin, and corticotropin-releasing factor). Signals from the periphery, such as nutrients and hormones, alter the activity of various neural pathways, and it is in the hypothalamus that this information is received, and then the appropriate effector systems involved in maintaining energy balance (e.g., appetite and insulin secretion) are activated. Alterations in hypothalamic activity (i.e., neurotransmitter synthesis and release) may play an important role mediating impairments in metabolic homeostasis (including obesity and impairments in glucose homeostasis). Experiments in the laboratory will examine the regulation of hypothalamic activity (e.g., neuropeptide gene expression) by peripheral nutrient and hormonal signals (e.g., glucose and insulin). Experiments are aimed at: 1) characterizing the alterations in hypothalamic activity associated with animal models of obesity and non-insulin dependent diabetes mellitus, and 2) examining whether these alterations may play a causative role in the development of these disorders.
Neuroendocrinology of Reproduction
Luteinizing hormone-releasing hormone (LHRH) is a neuropeptide that stimulates the release of luteinizing hormone and follicle stimulating hormone from the pituitary. LHRH is synthesized in the hypothalamus and LHRH release from nerve terminals in the median eminence is considered to play a primary role in the control of reproduction. There is abundant evidence that release of LHRH from the median eminence is influenced by numerous neurotransmitters, neuromodulators, and circulating hormones. However, relatively little is known about the factors important in the regulation of LHRH gene expression and LHRH synthesis.
Recent evidence suggests that regulation of LHRH gene expression is an important parameter in the regulation of reproduction and is important in the proper functioning of the hypothalamic-pituitary-gondal axis. Objectives of research in the laboratory include determining the factors important in the regulation of LHRH activity, and the physiological organization of the LHRH neurons in the hypothalamus . Experiments in rats will be aimed at 1) determining whether the synthesis of LHRH is tightly coupled to the release of LHRH, 2) identifying molecular markers of neuronal activity (e.g. immediate early gene products such as c-fos and c-jun) that can be used to study the regulation of LHRH synthetic activity, and 3) examining the physiological significance of localization of galanin (a neuropeptide that is co-released with LHRH from nerve terminals in the median eminence) in a sub-population of LHRH cells in the hypothalamus.
These experiments will provide insight into the regulation of LHRH neuronal activity, and the organization of the LHRH neuronal system that plays a crucial role in the regulation of reproductive function.
For a list of my publications, please refer to the following link and search for “Bergen HT”:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed
