Browsing by Subject "Amygdaloid body"
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- ItemIs the lateral septum's inhibitory influence on the amygdala mediated by GABA-ergic neurons?(2004) Austin, Mason; Thomas, EarlPrevious studies suggest that the lateral septum and amygdala are critical in the production and regulation of anxiety. The lateral septum may express its anxiolytic properties by directly inhibiting the activity of the amygdala. The present study examines whether this connection is primarily mediated by GABA-ergic neurons. Rats were fully sedated and an acute recording electrode was placed in the central nucleus of the amygdala; the lateral septum was stimulated during recording. Picrotoxin was injected intraperitoneally and recording was repeated. The interaction effect of picrotoxin and stimulation support the conclusion that GABA does play a central role in this connection.
- ItemOxytocin Receptor Plasticity Following a Hormone-Simulated Pregnancy in Syrian Hamsters: Implications for Postpartum Mood Disorders(2018) Benedetto, Lauren E.; Been, LauraDespite 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 Results indicate an increase in oxytocin receptor density in the raphe nuclei among hormone-withdrawn animals as compared to controls, suggesting that the region could be implicated in the etiology of anxiety-like behavior during the postpartum period.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as measured by the Open Field Test and increased anxiety-like behavior as measured by the Elevated Plus Maze in hormone-withdrawn animals.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.
- ItemPostpartum oxytocin receptor plasticity in Syrian hamsters: Implications for the treatment of peripartum mood disorders(2018) Heaton, Elizabeth C.; Been, LauraPeripartum 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.
- ItemThe Neurobiological Etiology of Postpartum Depression: The Role of Oxytocin in the Hypothalamus and the Amygdala(2017) Bodie, Clio; Been, LauraIn 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.
- ItemThe Neurobiological Mechanisms of Postpartum Depression: The Role of Oxytocin in the Hypothalamus and Amygdala(2017) Amaral, Claudia F.; Been, LauraAlthough 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.