Dr. Michiru Hirasawa

Memorial University of Newfoundland
Researcher of the month: 
Sep 2004

Dr. Michiru Hirasawa is an assistant professor of neuroscience at Memorial University who has been remarkably successful in obtaining operating and equipment funding since she joined the Faculty of Medicine in 2003.

Dr. Hirasawa’s expertise is on synaptic physiology and her current research is on how neurons in the hypothalamus communicate in relation to control of appetite and energy expenditure. Last year she was awarded a CIHR annual operating grant of $54,810 over three years and a $52,659 equipment grant for her research on central control of energy homeostatis. She has also received CFI funding of $133,931 for cellular electrophysiology and photostimulation system for investigation of central mechanism of body weight control.

Most recently, Dr. Hirasawa was awarded a NSERC discovery grant of $147,550 over five years for investigations on synaptic activity from supraoptic nucleus neurons (SON) in the adult brain. SON neurons synthesize and secrete neuropeptides that are important for regulation of milk secretion, salt-water balance, etc. and synaptic remodeling is thought to be necessary during lactation or dehydration to meet the increased demand for neuropeptide release. It is largely unknown what causes the remodeling and Dr. Hirasawa will, by recording synaptic activity from SON neurons in brain slices (where original synaptic connectivity is preserved) investigate the mechanisms that initiate the remodeling.

As a PhD student in at the University of Tokyo, Japan, she worked on the hypothalamus in whole animals (rats). By recording electrical activity of neurons, she discovered that the ventromedial nucleus of the hypothalamus was involved in controlling heart rate, blood pressure and metabolism during sleep. She and her husband took up post-doctoral fellowships at the University of Calgary in Alberta and she continued her research on the hypothalamus using in vitro electrophysiological technique on brain slices with particular focus on synaptic transmission. Her research involved the supraoptic nucleus that controls hormone secretion that regulates the cardiovascular system and lactation.

Dr. Hirasawa is now trying to combine her research experience in these two nuclei and study the synaptic physiology and pathology in the key brain areas for control of appetite and energy expenditure. She is particularly interested the the brain circuits located in the hypothalamus that are important for controlling body weight.

The main difficulty in Dr. Hirasawa’s research is that neurons in these areas of the hypothalamus are not all the same. Neurons make different kinds of neurotransmitters and have different roles, and in the hypothalamus the diversity is especially huge. But she is confident that with the advance of knowledge and technology she will be able to identify the type of neuron being recorded, and by taking advantage of that plus the recording technique, study specific class of neurons.

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