Estrogen- and experience- dependent Fos expression in locus coeruleus in adult female mice following exposure to pup calls Open Access

Gumaste, Ankita Anand (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/z029p577h?locale=en
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Abstract

A key aspect to studying maternal behavior is understanding the mechanisms governing a mother's heightened response to infant sensory cues when compared to non-mothers. Previous literature has focused on the motivational mechanisms behind this enhanced response, however sensory changes following parturition contribute as well. In part, increased detection of infant cues by mothers evidently results from neural plasticity within a number of sensory systems following parturition. Two of the main factors that may contribute to heightened response to infant cues in mothers include experience with offspring and changes in the female's hormonal environment. Immediately before parturition, plasma estradiol levels reach a peak in mothers and may play a role not only in eliciting maternal behavior, but also in the processing of salient auditory stimuli. Estradiol may serve to prime neuromodulatory systems that facilitate brain plasticity including in the auditory system. This concept is of particular interest, as norepinephrine plays a role in both maternal behavior and acoustic sensitivity to salient stimuli. Here, we examine the effects of estradiol and maternal experience on Fos expression in the locus coeruleus, the sole source of norepinephrine to the forebrain, in adult virgin ovariectomized CBA/CaJ female mice following exposure to pup calls. We examined these effects using cohorts of animals with manipulated levels of maternal experience and estradiol levels. Following exposure to a pup call stimulus, we measured Fos protein expression in the locus coeruleus. Our results suggest that animals with elevated levels of estradiol and maternal experience have greater Fos expression in the locus coeruleus following exposure to pup calls when compared with animals lacking estradiol but with maternal experience. Additionally, animals with maternal experience but lacking estradiol have less Fos expression in the locus coeruleus following exposure to pup calls when compared with animals lacking estradiol and without maternal experience. This study suggests that elevated levels of estradiol in animals with pup experience enhances the processing of salient infant auditory cues. Additionally, the findings suggest that pup calls may be salient, perhaps for different reasons, for both animals with pup experience as well as those without pup experience.

Table of Contents

Table of Contents

Introduction..........................................................................1 Materials and Methods............................................................8 Results...............................................................................13 Discussion..........................................................................15 Table 1...............................................................................21 Table 2...............................................................................22 Figure 1.............................................................................23 Figure 2.............................................................................24 Figure 3.............................................................................25 Figure 4.............................................................................26 Figure 5.............................................................................27 Figure 6.............................................................................28 Figure 7.............................................................................29 References.........................................................................30

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