The goal of the proposed research is to develop a new and unique animal of neuroendocrine function useful for the study of the biological basis of mate choice or sexual partner preference. We have chosen the domestic ram because they display a naturally occurring variation in partner preference, such that 4-6% of range-bred populations prefer male sexual partners (i.e. male-oriented (MO) rams) in contrast to the majority of rams which prefer female sexual partners (i.e. female-oriented rams (FO) rams). Moreover, rams are dependent on gonadal hormones to facilitate sexual behaviors, and a great deal known about their sexual development and neuroendocrinology. Preliminary experiments, using rams that were characterized according to their sexual partner performances revealed that in comparison to FO rams, MO rams exhibited significantly lower levels of aromatase activity in the preoptic area (POA) of the brain, an area which is essential for the control of male sexual behaviors. In addition, our results suggest that MO rams may exhibit deficits in testicular hormone secretion. Further characterization and development of this ram model will provide a novel experimental animal system useful for studies in mental health, neuroscience, sexual behavior, neuroendocrinology and developmental neurobiology. The experiments proposed in this application will furnish important information that is needed to formulate and test novel hypotheses about the biological basis of sexual orientation in higher mammals including humans. For this purpose, we will perform the following specific aims:
Specific Aim 1. To determine whether the expression MO sexual partner preference behavior is associated with altered function of the hypothalamic-pituitary-gonadal axis in rams.
Specific Aim 2. To determine whether male sheep that exhibit MO sexual partner preference behavior have associated morphological differences in the size and neurochemical content of specific preoptic-anterior hypothalamic nucleic in comparison to FO males.
Specific Aim 3. To determine MO sexual partner preference behavior can be artificially produced in genetic male sheep by providing male lamb fetuses of prenatal estrogen stimulation. When completed, this research will have characterized a new and unique animal model that will be useful for understanding the complex interactions between hormones, development, sensory processes, and behavior.

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Research Project (R01)
Project #
5R01RR014270-03
Application #
6529844
Study Section
National Center for Research Resources Initial Review Group (RIRG)
Program Officer
Grieder, Franziska B
Project Start
2000-09-15
Project End
2003-08-31
Budget Start
2002-09-01
Budget End
2003-08-31
Support Year
3
Fiscal Year
2002
Total Cost
$244,880
Indirect Cost
Name
Oregon Health and Science University
Department
Physiology
Type
Schools of Medicine
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Mirto, A J; Austin, K J; Uthlaut, V A et al. (2017) Fos Expression in the Olfactory Pathway of High- and Low-Sexually Performing Rams Exposed to Urine from Estrous or Ovariectomized Ewes. Appl Anim Behav Sci 186:22-28
Reddy, R C; Estill, C T; Meaker, M et al. (2014) Sex differences in expression of oestrogen receptor ? but not androgen receptor mRNAs in the foetal lamb brain. J Neuroendocrinol 26:321-8
Roselli, C E; Stormshak, F (2012) Ontogeny of cytochrome p450 aromatase mRNA expression in the developing sheep brain. J Neuroendocrinol 24:443-52
Alexander, Brenda M; Skinner, Donal C; Roselli, Charles E (2011) Wired on steroids: sexual differentiation of the brain and its role in the expression of sexual partner preferences. Front Endocrinol (Lausanne) 2:42
Roselli, Charles E; Reddy, Radhika C; Kaufman, Katherine R (2011) The development of male-oriented behavior in rams. Front Neuroendocrinol 32:164-9
Roselli, Charles E; Estill, Charles T; Stadelman, Henry L et al. (2011) Separate critical periods exist for testosterone-induced differentiation of the brain and genitals in sheep. Endocrinology 152:2409-15
Roselli, C E; Stormshak, F (2010) The ovine sexually dimorphic nucleus, aromatase, and sexual partner preferences in sheep. J Steroid Biochem Mol Biol 118:252-6
Roselli, C E; Estill, C T; Stadelman, H L et al. (2009) The volume of the ovine sexually dimorphic nucleus of the preoptic area is independent of adult testosterone concentrations. Brain Res 1249:113-7
Roselli, C E; Stormshak, F (2009) Prenatal programming of sexual partner preference: the ram model. J Neuroendocrinol 21:359-64
Roselli, Charles E; Stormshak, Fred (2009) The neurobiology of sexual partner preferences in rams. Horm Behav 55:611-20

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