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Access Type

Open Access Thesis

Document Type


Degree Program

Neuroscience & Behavior

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



Postpartum depression is a serious psychiatric condition that has deleterious effects on the mother and poses a risk for the mother-infant relationship and ultimately the infant’s development.

Maternal anhedonia and social communication deficits are two major clinical features central to postpartum depression that likely contribute to deficits in parenting. The present study used Wistar-Kyoto (WKY) mother rats, an animal model of depression which we have developed to examine the postpartum disorder, to investigate the relationship between maternal anhedonia, social communication deficits and parenting disturbances. Rats produce ultrasonic vocalizations (USVs) in different social contexts, and USVs are becoming an increasingly valuable assay for behavioral phenotyping. Alterations of the ultrasound patterns have been reported in several models of neuropsychiatric disorders, including those associated with communicative/social deficits, and can also provide reliable insight into the affective state of the mother rat during social interactions with her litter. In the first study, WKY and control Sprague-Dawley (SD) postpartum females were examined for their affective responses to social cues from pups, as measured by their ultrasonic vocalizations (USVs) during a 30-minute maternal behavior test following 20 minutes of mother-litter separation. Total number of calls, acoustic frequency and duration of calls, and individual USV profiles were analyzed in conjunction with maternal behavior. Both WKY and SD mothers predominantly produced ~50 kHz USVs when interacting with the pups in the maternal behavior test. WKY mothers emitted more trill-type USVs as is compared with SD mothers. Similarly, WKY mothers exhibited substantial disturbances in theirmaternal behavior. A second experiment evaluated the therapeutic efficacy of adenosine A2A receptor antagonism as a novel treatment strategy for postpartum depression. Emerging evidence indicates that the neuromodulator adenosine, particularly through actions on adenosine A2A receptors, modulates behavioral functions associated with the mesocorticolimbic DA system, including cognitive and motivational processes. Results indicate that acute MSX-3 administration did not attenuate the parenting disturbances of WKY or affect the USV emissions of either strain.

Taken together, these results provide evidence for the presence of maternal USVs during motherlitter interactions, and further suggest that variations in USVs produced by mothers during social interaction with their pups may function as an index of their affect. Rat USVs may be used to study the neurobiological mechanisms underlying maternal affect in animal models of postpartum disorders.