Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Emaya Moss - Louisiana State University
Oxytocin is a peptide hormone produced by neurons in the supraoptic and paraventricular nuclei of the hypothalamus. These synthesizing neurons release oxytocin from the pituitary gland to the general blood circulation in response to physiological demands. Oxytocin induces the let down of milk from the mammary glands in mothers in response to suckling and auditory/visual cues expressed by the offspring. In addition to this well-known effect of oxytocin on the mammary glands, it is also released within the brain and foster a variety of social behaviors. Oxytocin promotes pair bonding, relationship attachment and heightens sexual arousal in humans. Furthermore, it aids in the expression of maternal behaviors such as pup retrieval in rodents. The biological activity of oxytocin is mediated by oxytocin receptors (OXTR) located on peripheral organs as well as in the brain. Oxytocin influences social behaviors by binding to OXTRs located in the brain regions known to regulate social behaviors, such as the prefrontal cortex, nucleus accumbens and amygdala, and reproductive behaviors, such as the olfactory bulb. In particular, OXTRs are present in the preoptic area (POA) where hormone-sensitive sexually dimorphic nuclei exist. The expression of OXTR is believed to be estrogen dependent. However, OXTR in the brain of female mice with their ovaries removed (ovariectomized) were similar to that of an intact female. The most notable differences existed in the medial preoptic area (Shauma). This indicates that not all the expression of OXTRs are estrogen dependent or sexually dimorphic. If sexually dimorphic behaviors are resulting from the sex difference in the neural circuits than ERa-OXTR neurons may be involved in the sex differences in behavior. This information will deeper our understanding of ERa-OXTR neurons in the brain which is an essential step to understanding the sex differences in oxytocin induced social behaviors. The proposed study will investigate and identify the locations of ERa expressing OXTR populations in the mice brain. Immunocytochemistry was performed on twelve, six female and six male OXTR-Venus heterozygous (+/-) mice ranging from the ages of six to eight months. An OXTR-Venus heterozygous (+/-) mouse is an OXTR-Venus mouse in which a part of the OXTR gene was replaced with Venus (a variant of the yellow fluorescent protein) cDNA (Yoshida). The brains were extracted and postfixed with 4% paraformaldehyde. For double-fluorescence imaging of Venus and immunocytochemistry of estrogen receptor α, the brain sections were processed with polyclonal anti-ERα antibody. This allows us to visually identify the populations of receptors under the fluorescence microscope. Slices (250 μm) containing the hypothalamic periventricular nucleus were collected using a vibrating microtome. The sections were then mounted and scanned to identify the regions of OXTR populations expressing ERa. Each region expressing ERa-OXTR neurons will be counted and mapped on the mouse brain atlas. The expected results are an enriched amount of clusters on Era-OXTR neurons receptors in the pre-optic area. Understanding sex differences in oxytocin-mediated, sex-specific social behavior will provide useful insight into sex-specific pharmacological interventions that treat sex typical psychiatric disorders, such as postpartum depression. Source Kaustubh Sharma,Ryan LeBlanc,Masudul Haque,Katsuhiko Nishimori,Madigan M. Reid,Ryoichi Teruyama Published: July 11, 2019https://doi.org/10.1371/journal.pone.0219784Sexually dimorphic oxytocin receptor-expressing neurons in the preoptic area of the mouse brain Yoshida M, Takayanagi Y, Inoue K, Kimura T, Young LJ, Onaka T, et al. Evidence that oxytocin exerts anxiolytic effects via oxytocin receptor expressed in serotonergic neurons in mice. J Neurosci. 2009;29(7):2259–71. pmid:19228979.
Funder Acknowledgement(s): The Louis Stokes Louisiana Alliance for Minority Participation (LS-Lamp)
Faculty Advisor: Ryoichi Teruyama, firstname.lastname@example.org
Role: I am instrumental in the data analysis portion of the project. I will aid in scanning the slides. I will be responsible for identifying the cluster via a fluorescence microscope and mapping each of ERa-OXTR neuron populations on the mouse brain atlas.