Biology subjects

Been, L. E.

Publications and source records attributed to Been, L. E..

5 recordsLinked to original sources

bioRxiv2025

{triangleup}FOSB in the nucleus accumbens core is required for increased anxiety, but not decreased social motivation, following estrogen withdrawal in female mice

During pregnancy, estrogen levels rise dramatically, but quickly drop to prepartum levels following birth, and remain suppressed until ovulation resumes. This "postpartum estrogen withdrawal" state has been linked to changes in the brain and behavior in humans and rodents. Previous research has demonstrated that following a hormone-simulated pseudopregnancy (HSP), an experimental model of postpartum estrogen withdrawal, female mice show increased anxiety-like behaviors and decreased social motivation. Further, these behavioral changes occur concurrently with an increase in {Delta}FOSB, a transcription factor associated with stable long-term plasticity, in the nucleus accumbens core. To test whether this increase in {Delta}FOSB is required for these behavioral changes, we used a viral-mediated gene transfer approach to prevent {Delta}FOSB-mediated transcription in the NAcC during HSP and found that it reduced the high-anxiety behavioral phenotype in estrogen-withdrawn females. However, preventing {Delta}FOSB-mediated transcription had little effect on social motivation. Together, these results suggest that postpartum estrogen withdrawal increases {Delta}FOSB in the NAc core to impact anxiety-like behaviors, but not social motivation, following estrogen withdrawal.

neuroscience↗

bioRxiv2023

Long-Term Oral Tamoxifen Administration Decreases Brain Derived Neurotrophic Factor in the Hippocampus of Female Long-Evans Rats

Tamoxifen is a selective estrogen receptor modulator (SERM) that is commonly used as an adjuvant drug therapy for estrogen receptor-positive breast cancers. While this drug is effective at reducing the rate of cancer recurrence, many patients report unwanted cognitive and affective side effects such as brain fog, confusion, memory impairment, anxiety, and depression. Despite this, the impacts of chronic tamoxifen exposure on the brain are poorly understood, and rodent models of tamoxifen exposure do not replicate the chronic oral administration seen in patients. We therefore used long-term ad lib consumption of medicated food pellets in adult female rats to model chronic tamoxifen exposure in a clinically-relevant way. Gonadally-intact adult female Long-Evans Hooded rats consumed tamoxifen medicated food pellets for approximately 12 weeks while control animals received standard chow. At the conclusion of the experiment, animals were euthanized, and blood and brain samples were collected for analyses. Blood tamoxifen levels were measured using a novel ultra-performance liquid chromatography-tandem mass spectrometry assay, which found that this administration paradigm produced serum levels of tamoxifen similar to those in human patients. In the brain, brain derived neurotrophic factor (BDNF) was visualized in the hippocampus using immunohistochemistry and quantified using background-subtracted optical densitometry. Chronic oral tamoxifen treatment resulted in a decrease in BDNF expression across several regions of the hippocampus. Together, these findings provide a novel method of modeling and measuring chronic oral tamoxifen exposure, and suggest a putative mechanism by which tamoxifen may cause cognitive and behavioral changes reported by patients.

neuroscience↗

bioRxiv2022

Elevated estradiol during a hormone simulated pseudopregnancy decreases sleep and increases hypothalamic activation in female Syrian hamsters

Sleep disruptions are a common occurrence during the peripartum period. While physical and environmental factors associated with pregnancy and newborn care account for some sleep disruptions, there is evidence that peripartum fluctuations in estrogens may independently impact sleep. We therefore used a hormone-simulated pseudopregnancy in female Syrian hamsters to test the hypothesis that pregnancy-like increases in estradiol decrease sleep in the absence of other factors. Adult female Syrian hamsters were ovariectomized and given daily hormone injections that simulate estradiol levels during early pregnancy, late pregnancy, and the postpartum period. Home cage video recordings were captured at seven timepoints and videos were analyzed for actigraphy. During "late pregnancy," total sleep time and sleep efficiency were decreased in hormone-treated animals during the white light period compared to vehicle controls. During both "early pregnancy" and "late pregnancy," locomotion was increased in the white light period for hormone-treated animals; this change continued into the "postpartum period" for animals who continued to receive estradiol treatment, but not for animals who were withdrawn from estradiol. At the conclusion of the experiment, animals were euthanized and cFos expression was quantified in the ventral lateral preoptic area (VLPO) and lateral hypothalamus (LH). Animals who continued to receive high levels of estradiol during the "postpartum" period had significantly more cFos in the VLPO and LH than animals who were withdrawn from hormones or vehicle controls. Together, these data suggest that increased levels of estradiol during pregnancy are associated with sleep suppression which may be mediated by increased activation of hypothalamic nuclei.

neuroscience↗

bioRxiv2022

Postpartum estrogen withdrawal induces deficits in affective behaviors and increases ΔFosB in D1 and D2 neurons in the nucleus accumbens core in mice

In placental mammals, estradiol levels are chronically elevated during pregnancy, but quickly drop to prepartum levels following birth. This may produce an "estrogen withdrawal" state that has been linked to changes in affective states in humans and rodents during the postpartum period. The neural mechanisms underlying these affective changes, however, are understudied. We used a hormone-simulated pseudopregnancy (HSP), a model of postpartum estrogen withdrawal, in adult female C57BL/6 mice to test the impact of postpartum estrogen withdrawal on several behavioral measures of anxiety and motivation. We found that estrogen withdrawal following HSP increased anxiety-like behavior in the elevated plus maze, but not in the open field or marble burying tests. Although hormone treatment during HSP consistently increased sucrose consumption, sucrose preference was generally not impacted by hormone treatment or subsequent estrogen withdrawal. In the social motivation test, estrogen withdrawal decreased the amount of time spent in proximity to a social stimulus animal. These behavioral changes were accompanied by changes in the expression of {Delta}FosB, a transcription factor correlated with stable long-term plasticity, in the nucleus accumbens (NAc). Specifically, estrogen-withdrawn females had higher {Delta}FosB expression in the nucleus accumbens core. Using transgenic reporter mice, we found that this increase in {Delta}FosB occurred in both D1- and D2-expressing cells in the NAc core. Together, these results suggest that postpartum estrogen withdrawal impacts anxiety and motivation and increases {Delta}FosB in the NAc core.

neuroscience↗

bioRxiv2020

Estrogen withdrawal alters oxytocin signaling in the paraventricular hypothalamus and dorsal raphe nucleus to increase postpartum anxiety

BackgroundEstrogen increases dramatically during pregnancy, but quickly drops below pre-pregnancy levels at birth and remains suppressed during the postpartum period. Clinical and rodent work suggests that this postpartum drop in estrogen results in an "estrogen withdrawal" state that is related to changes in affect, mood, and behavior. Most studies examining the effect of estrogen withdrawal on the brain have focused solely on the hippocampus. MethodsWe used a hormone-simulated pseudopregnancy model in Syrian hamsters, a first for this species. Ovariectomized females were given daily injections to approximate hormone levels during gestation and then withdrawn from estrogen to simulate postpartum estrogen withdrawal. Subjects were tested for behavioral assays of anxiety and anhedonia during estrogen withdrawal. Following sacrifice, neuroplasticity in oxytocin-producing neurons in the paraventricular nucleus of the hypothalamus (PVH) and its efferent targets was measured. ResultsEstrogen-withdrawn females had increased anxiety-like behaviors in the elevated plus and open field, but did not differ from controls in sucrose preference. Furthermore, estrogen-withdrawn females had more oxytocin-immunoreactive cells and oxytocin mRNA in the PVH, as well as an increase in oxytocin receptor density in the dorsal raphe nucleus (DRN). Finally, blocking oxytocin receptors in the DRN during estrogen withdrawal prevented the high-anxiety behavioral phenotype in estrogen-withdrawn females. ConclusionsEstrogen withdrawal alters oxytocin signaling in the PVH and DRN to increase anxiety-like behavior during the postpartum period. More broadly, these experiments suggest Syrian hamsters as a novel organism in which to model the effects of postpartum estrogen withdrawal on the brain and anxiety-like behavior.

neuroscience↗