Browsing by Subject "Oxytocin"

Now showing 1 - 7 of 7
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    Oxytocin Receptor Plasticity Following a Hormone-Simulated Pregnancy in Syrian Hamsters: Implications for Postpartum Mood Disorders
    (2018) Benedetto, Lauren E.; Been, Laura
    Despite the fact that approximately 15‒20% of women develop postpartum depression and/or anxiety, and that the resulting outcomes for both the mother and her child are negative, the underlying neurobiological mechanisms of the disorders remain poorly understood. Previous research suggests that ovarian hormone fluctuations as well as changes in oxytocin signaling that occur at parturition and in the postpartum likely play a role in the etiology of these disorders. Given the increase in oxytocin-producing neurons in the paraventricular nucleus (PVN) of the hypothalamus following a hormone simulated pregnancy, Experiment 1 sought to examine oxytocin receptor levels in PVN efferents, particularly in the medial amygdala (MeA), nucleus accumbens (NAc), bed nucleus of the stria terminalis (BNST), and raphe nuclei. Results indicate an increase in oxytocin receptor density in the raphe nuclei among hormone-withdrawn animals as compared to controls, suggesting that the region could be implicated in the etiology of anxiety-like behavior during the postpartum period. Unexpectedly, behavioral results indicate reduced non-specific locomotor ability as measured by the Open Field Test and increased anxiety-like behavior as measured by the Elevated Plus Maze in hormone-withdrawn animals. Experiment 2 sought to explore whether neurodegeneration was responsible for the decreased oxytocin-producing neurons found in hormone-sustained animals. Unexpectedly, cell death is visible in hormone-withdrawn and not hormone-sustained animals, suggesting that some neuroplasticity may be taking place. Overall, these two experiments add to our understanding of the brain and behavior following hormone-simulated pregnancy in hamsters, which may inform our understanding the postpartum period in humans.
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    Plasticity of Oxytocin Receptors in the Postpartum Period Using a Hamster Model
    (2018) Taveras, Shantal; Been, Laura
    The deleterious consequences of postpartum depression and anxiety (PPD) on the mother-child dyad has greatly incentivized more research in the neurobiological mechanisms during the peripartum period. Several studies have stipulated that neurobiological and hormonal components may lead to the etiology of PPD. However, a greater understanding of the complexities of PPD will not unfold until knowledge on the typical patterns of puerperium is prioritized. In the current study, we simulated pregnancy in a hamster model to investigate changes in oxytocin receptor density in the efferents of the paraventricular nucleus (PVN). For the four regions of interest, we predicted a decrease in oxytocin receptors density for the estrogen-withdrawn hamsters within the postpartum period. The raphe nucleus (RN) was the only region of interest that attained statistical significance. Contrary to our hypothesis, the estrogen-withdrawn group exhibited a significant increase of oxytocin receptors compared to the control group in this region. Utilizing an open field test and elevated plus maze, we also expected to observe less anxiety-like behaviors from the estrogen-withdrawn group. However, our results did not reveal any statistical significance for anxiety-like behaviors. Following previous results, this study also investigated the overall neurodegeneration within the PVN, specifically an increase of cell-death in the estrogen-sustained group. After qualitative analysis, we visualized greater fluoro-jade staining, a measure of neurodegeneration, within the estrogen-withdrawn group. By gaining greater comprehension of the estrogen and oxytocin pathway, it will lead to a greater understanding of the typical postpartum period and, thereby, the intricacies involved in the peripartum period.
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    Postpartum Oxytocin Receptor Plasticity And Anxiety-Like Behavior in Syrian Hamsters: The Potential Role of the Dorsal Raphe Nuclei
    (2018) Levine, Taylor; Been, Laura
    The postpartum period is a time of high vulnerability for females to develop depression. Not only does postpartum depression significantly hinders the motivation and enjoyment that a mother feels in her new role, but also the development of the offspring, doubling the impact of this unique affective disorder. Oxytocin, a hormone involved in birth, maternal behavior, depression, and anxiety may help to untangle the link between postpartum hormonal levels and the occurrence of postpartum depression. The present study examined oxytocin receptor plasticity in efferents of the paraventricular nucleus, the main source of central oxytocin, in an animal model following a hormone-simulated pregnancy. Estrogen-withdrawn females exhibited a significantly greater density of oxytocin receptors in the dorsal raphe nuclei and there were no significant differences in receptor density between hormonal treatment groups in other efferents examined. Estrogen-withdrawn females also displayed higher levels of anxiety-like behavior than estrogen-sustained animals in the Elevated Plus Maze. Ultimately, the present study aimed to understand the role of oxytocin signaling in postpartum mood disturbances and how oxytocin may meet the demand as a novel, targeted treatment for postpartum depression.
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    Postpartum oxytocin receptor plasticity in Syrian hamsters: Implications for the treatment of peripartum mood disorders
    (2018) Heaton, Elizabeth C.; Been, Laura
    Peripartum mood disorders, if left untreated, result in negative outcomes for both the mother and child. Despite these severe consequences, the neurobiology of peripartum mood disorders is not well understood. The present study aims to build upon previous research investigating the role of oxytocin in neuroplastic and behavioral changes during the peripartum period. Past work found a significant increase in oxytocin-immunoreactive neurons in the PVN as a result of hormone withdrawal in a hormone-simulated pregnancy model conducted in Syrian hamsters. Using the same model, we studied post-synaptic plasticity: specifically, we assessed which PVN efferents, if any, experienced changes in oxytocin receptor expression using receptor autoradiography. The regions of interest in this study were medial amygdala (MA), nucleus accumbens (NA), bed nucleus of the stria terminalis (BNST), and the raphe nuclei as each of these four areas are heavily involved in the production of maternal behavior. There was a significant increase in OTR density in the dorsal raphe in the hormone withdrawn group as compared to oil control. Changes in OTR density in the dorsal RN, which regulates serotonergic activity and anxiety- and depression-related behavior in humans and rodents, may play a role in the development or sustainment of peripartum mood disorders.
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    The Neurobiological Etiology of Postpartum Depression: The Role of Oxytocin in the Hypothalamus and the Amygdala
    (2017) Bodie, Clio; Been, Laura
    In the current study, we simulated the hormonal conditions of pregnancy and a postpartum period in a Syrian hamster model in order to better understand the neurobiological etiology of postpartum depression (PPD). PPD is a distinct subtype of major depressive disorder, which develops in new mothers during the first few weeks after delivery. It is a prevalent disorder and has incredibly harmful effects on both the mother and her infant, but not much is understood about its etiology, which makes treatment difficult. We hypothesized that after estrogen withdrawal produced a PPD-like state, subjects would show behavioral indicators of anhedonia through the Sucrose Preference Test. We also expected to find decreased levels of oxytocin producing cells in the paraventricular nucleus of the hypothalamus (PVN) and the medial amygdala of animals that experienced hormone withdrawal, which we believed might contribute to the development of PPD. We did not find any significant differences in the behavioral measures testing anhedonia. Our neurobiological findings were the opposite of what we hypothesized- we found significantly higher quantities of oxytocin producing neurons in the PVN of hamsters that experienced hormone withdrawal. These findings may indicate that oxytocin contributes to dysregulation of the HPA axis in the postpartum or that oxytocin fluctuations within the postpartum period affect PPD. Future research should further explore the role of oxytocin in the hypothalamus and amygdala, as it appears to be associated with PPD.
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    The Neurobiological Mechanisms of Postpartum Depression: Observing Oxytocin’s Role in the Paraventricular Nucleus of the Hypothalamus Using a Hamster Model
    (2017) Lee, Rachel H.; Been, Laura
    Postpartum depression is a condition that affects new mothers’ cognition and behavior, as well as her ability to raise the child. It affects up to 15% of women who give birth and has a wide variety of symptoms. Despite its prevalence and severity, though, the neurobiological mechanisms underlying the condition remain understudied. During pregnancy and postpartum, dramatic hormone changes occur and may play a key role in the neurobiological and behavioral aspects in postpartum depression – of note is the rise in ovarian hormones followed by their sudden drop after giving birth. Current research also suggests that the dysregulation of the hormone oxytocin (OXT), which is synthesized in the paraventricular nucleus of the hypothalamus (PVH) and medial amygdala (MA), underlies the onset of postpartum depression. We modeled the postpartum hormonal changes in a hamster model, and specifically looked for changes in OXT-producing neurons in the PVH and MA using an immunohistochemical reaction. During behavioral testing, we hypothesized that hormone withdrawn animals would show a decreased preference for sugar water, and during immunohistochemistry, we hypothesized that this same group would show a significantly lower count of OXT cells, while control animals would show a significantly higher count. Interestingly, results showed the opposite of what we predicted – hormone withdrawn animals had a significantly higher count of OXT cells and vice versa. These results contain implications for potential fluctuations of OXT levels within the postpartum period itself.
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    The Neurobiological Mechanisms of Postpartum Depression: The Role of Oxytocin in the Hypothalamus and Amygdala
    (2017) Amaral, Claudia F.; Been, Laura
    Although postpartum depression has a prevalence of approximately 15% and can result in negative outcomes for both the mother and her child, its underlying neurobiological mechanisms remain mostly unknown. Previous research suggests that ovarian hormone fluctuations that occur during the postpartum period could underlie depressive symptoms in postpartum depression. Studies have also suggested that changes in oxytocin signaling could also play a role in the etiology of this disorder. The present study adapts the ovarian withdrawal model of postpartum depression to a Syrian hamster animal model in order to study the neurobiological mechanisms of postpartum depression. Its aim is to test whether hormone withdrawal during the postpartum period results in changes in oxytocin signaling between the paraventricular nucleus and the medial amygdala. It is hypothesized that these neurobiological changes could be implicated in depressive-like behavior during the postpartum period.