Breedlove Jordan Lab

Erich N. Ottem

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My research interests focus on excitatory glutamatergic signaling in the maintenance of the pre- and postsynaptic machinery at axo-dendritic contacts within the context of the field of neuroendocrinology. My previous research involved delineating the interaction of ovarian steroids with glutamatergic and GABAergic signaling in the generation of gonadotropin-releasing hormone surge generation.

Currently, I am exploring the mechanisms by which androgens maintain the dendritic arborization of the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) motoneurons. Androgens may preserve the dendritic arborization observed in adult male rats via increased glutamatergic input to these neurons and/or by maintaining postsynaptic density proteins required for both synaptic stability and for dendritic expansion. In adulthood, the peptide brain-derived neurotrophic factor (BDNF) is required for the ability of androgen to maintain dendritic arborization. In many neural systems throughout the central nervous system, BDNF coordinates with glutamatergic signaling to maintain the structure and functioning of the dendrite arbor, as well as maintaining postsynaptic specializations. Interestingly, potential sources of BDNF that may be involved in maintaining SNB motoneurons may originate from presynaptic neurons, as a retrograde signal from the target muscles, as an autocrine factor from the SNB motoneurons, or from neighboring neurons or glia. It is my goal to determine the specific mechanisms by which glutamate, BDNF, and androgens interact to preserve the sexually dimorphic structure of SNB motoneuron dendrites in male rats.

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In addition, I am continuing the work of Dr. D.A. Monks; (previously a postdoctoral fellow in the Breedlove-Jordan Lab). We are developing a transgenic mouse line that possesses a floxed androgen receptor (AR; using Cre/lox directed knockout methodology) with the goal of producing lines of tissue-specific knock-out transgenic mice that have AR- SNB motoneuron target muscles, as well as lines of transgenic mice that have AR- motoneurons. Using these mice, we hope to delineate the relative roles that SNB target muscles and SNB motoneurons themselves play in the androgen-dependent development and maintenance of the sexually dimorphic SNB motoneuron system.

Examples of Erich's current research

Education

  • Ph.D., 2004: University of Massachusetts, Amherst, 1998-2004 (Neuroscience and Behavior Program)
  • Thesis: Glutamatergic and GABAergic Regulation of Luteinizing Hormone-Releasing Hormone Neurons.
  • Advisor: Dr. Sandra L. Petersen
  • B.S., 1997 Tennessee Technological University (Biology)

Publications

  • Ottem, E.N., Godwin, J.G., Krishnan, S., and Petersen, S.L. (2004) Dual-Phenotype GABA/Glutamate Neurons in the Adult Preoptic Area: Sexual Dimorphism and Function. Journal of Neuroscience, 24: 8097-8105.
  • Ottem E.N., Zuloaga D.G., and Breedlove S.M. (2004) Brain Gender: prostaglandins have their say. Nature Neuroscience, 7: 570-572.
  • Petersen, S.L., Ottem, E.N., and Carpenter, C.D. (2003) Direct and indirect regulation of GnRH neurons by estradiol. Biology of Reproduction. 69: 1771-1778.
  • Ottem, E.N., Godwin, J.G. and Petersen, S.L. (2002) Glutamatergic signaling through the N-methyl-D-aspartate receptor directly activates medial subpopulations of luteinizing hormone-releasing hormone (LHRH) neurons, but does not appear to mediate the effects of estradiol on LHRH gene expression. Endocrinology, 143:4837-45.

Manuscripts in Preparation

  • Ottem E.N. and Petersen, S.L. 'Distribution of dual-phenotype GABA/Glutamate neurons in the forebrain of the rat.'
  • Krishnan, S., Ottem E.N. and Petersen, S.L. 'Sex difference in dual-phenotype GABA/Glutamate neurons are abolished by prenatal exposure to dioxin'

Published Abstracts

  • Ottem, E.N. and Petersen, S.L (2003) Terminals containing vesicular glutamate transporter 2 and vesicular GABA transporter make synaptic contacts with luteinizing hormone-releasing hormone neurons. Society for Neuroscience, New Orleans, LA.
  • Ottem, E.N., Godwin, J.G., and Petersen, S.L. (2002) Coexpression of vesicular glutamate transporter 2 and glutamic acid decarboxylase mRNAs in specific nuclei of the preoptic area. Society for Neuroscience, Orlando, FL
  • Ottem, E.N. and Petersen, S. L. (2001) Estrogen regulation of glutaminase mRNA expression in GABAergic neurons of the AVPV/MPN. Society for Neuroscience, San Diego, CA.
  • Ottem, E.N. and Petersen, S.L. (2000) NMDAR1 mRNA is preferentially expressed by a medial subpopulation of LHRH neurons in the preoptic area. Society for Neuroscience, New Orleans, LA.
  • Ottem, E.N. and Petersen, S.L. (1999) Estrogen regulation of NMDAR1 gene expression in GABAergic neurons of the AVPV/MPN. Gordon Research Conference: Excitatory Amino Acids. Plymouth, NH.

Contact

  • Office: (517) 432-1674
  • Home: (517) 202-7891
  • Email: ottem@msu.edu