Research Interests: My research program is divided into two main themes: 1. Control of GnRH neuronal function by steroid hormones and afferent neuronal input (CIHR), and 2. Central and peripheral signals controlling neuronal cell types expressing neuropeptides linked to the regulation of energy homeostasis (CIHR). We also have received grants from NSERC on circadian regulation of hypothalamic neuropeptides. My long-term goal is to understand how the hypothalamus is able to achieve its diverse, but highly integrated control of basic physiological processes. All of the research projects initiated in my laboratory, or through collaborations with other research labs at the University of Toronto will help to define the molecular mechanisms involved in the neuroendocrine events initiated at the level of the hypothalamus through the analysis of specific cell models.
Keywords: Neuroendocrinology, reproductive biology, gonadotropin-releasing hormones, steroids, melatonin, neuropeptide Y, kisspeptin, neurotensin, proopiomelanocortin, ghrelin, proglucagon-derived peptides, feeding peptides, energy homeostasis, circadian rhythm, receptors, hypothalamus, hormones, insulin, leptin, estrogen, ciliary neurotropic factor, neuronal cell culture, molecular biology, transcription, signal transduction, cell biology.
Detailed Description: My research program currently has three major directions, which are described in more detail below.
Overview of Dr. Belsham’s Research Program:
The main focus of my laboratory is to understand, at the molecular level, how the hypothalamus achieves its diverse physiological functions. The neuroendocrine hypothalamus consists of a complex array of distinct neuronal phenotypes, each expressing a specific complement of neuropeptides, neurotransmitters and receptors. Many of our vital needs, such as those for growth, reproduction, nutrition, sleep, and stress responses, depend on hormonal balance or homeostasis, which is controlled by both external and internal stimuli or signals at the hypothalamic level.
A) Regulation of GnRH Neurons and Afferent Control Mechanisms:
In order to begin to dissect the molecular signals responsible for the release of specific peptides from individual hypothalamic neurons, my laboratory has focussed on the peptide that controls reproduction, gonadotropin-releasing hormone or GnRH. A large number of neuromodulators have been implicated in the control of reproductive function, as they have been found to regulate GnRH synthesis and secretion. My research program studies many aspects of GnRH function, and how afferent neurons affect the GnRH neurons. We also study the direct regulation of these afferent neurons, such as kisspeptin, neuropeptide Y, and gonadotropin inhibitory hormone, by steroids and other peripheral signals.
B) Generation and Characterization of Hypothalamic Cell Models:
We therefore analyze the direct actions of neuromodulators on individual GnRH neurons; the transcriptional mechanisms dictating the neurogenesis of individual hypothalamic neurons; and the development of specific immortalized hypothalamic neuronal cell models in order to understand the molecular mechanisms involved in interneuron communication and signaling. To address this last point, my laboratory has recently generated a number of cell models representing other specific cell types from the hypothalamus. These models have been used by many labs worldwide to understand how hypothalamic neurons function. These models include embryonic- and adult-derived cell models from the mouse and rat, and represent the many cell types found in the hypothalamus and hippocampus.
C) Analysis of the Neuropeptides involved in Energy Homeostasis:
We have a strong track record of neuroendocrine research, and have also expanded our research program to include the study of neuropeptides involved in both reproduction and energy homeostasis. Currently half of my research efforts are directed towards studies related to the function of the GnRH and afferent neurons, such as kisspeptin, neuropeptide Y and gonadotropin inhibitory hormone, and the other half has extended our research program to include studies of many of the neuropeptide-expressing neurons involved in energy homeostasis. These include neuropeptide Y, neurotensin, brain ghrelin, corticotropin-releasing hormone, and proopiomelanocortin. We are currently analyzing the changes in gene expression and signal transduction events after exposure to key peripheral signals such as insulin, ghrelin, glucose, leptin, and estrogen. We also study the mechanisms involved in neuroinflammatory signal transduction induced by exposure of neurons to excess nutrients, such as saturated fatty acids and high glucose. Importantly, there is also a direct relationship between nutritional status and reproduction, therefore my research program is poised to utilize all the information gained to provide insight into the complex nature of integrated neuroendocrine control of basic physiology.
Brain Slice, Neurons, Pancreas Cells,
Procedures: Elisa, gene expression analysis, immunohistochemistry, immunocytochemistry, in vivo hypothalamus immunocytochemistry, microarrays, molecular and cellular biology techniques, proteomics, qRT-PCR, retroviral and lentiviral transfections, RIA, RT-PCR, signal transduction characterization, siRNA, stereotaxic brain surgery, western blot.
Analytical Balances, Benchtop Centrifuge, Blotting Apparatus, Confocal Microscope, Culture Hood, Culture Incubators, Cryostat, Departmental Beta and Gamma Counters, Dissecting Microscope, Fluorescence Microscope, Fresh Tissue Sectioning systems, Gel Apparatus, Low and high speed centrifuge, Low and Ultralow Freezers, Microwave Oven, Mini Vortexer, Plate reader, ProBlot Hybridization Oven, Real-Time/Thermocycler. Setups for Electropherosis, Stirrer/Hot Plate, Water baths
Leigh Wellhauser – Post-doctoral Fellow
Alice Treen - MSc student
Dean Tran - MSc student
Biran Wong - MSc student
Wendy Ye - Undergraduate student
Vicky Luo - Undergraduate student
Ernesto Ramos - Undergraduate student
Iris Bian - Undergraduate student
Stephanie Kim - Undergraduate Student
Makram Aljghami - Undergraduate student
Lance Zhang - Undergraduate student
Jennifer Chalmers – Technician
Within the Department of Physiology: