Selection on vocal output affects laryngeal morphology in rats.

Although laryngeal morphology often reflects adaptations for vocalization, the structural consequences of selection for particular aspects of vocal behavior remain poorly understood. In this study, we investigated the effects of increased ultrasonic calling in pups on the adult larynx morphology in selectively bred rat lines. Laryngeal morphology was assessed using multiple techniques: mineralized cartilage volumes were compared in 3D-models derived from microCT scans, internal structure was compared using clearing and staining procedures combined with microscopy, cellular structure was compared using histology and microscopy, and element composition was assessed with scanning energy dispersive X-ray spectroscopy.

Selection on ultrasonic call rate in neonatal rats affects low frequency, but not ultrasonic, vocalizations in adults.

In this experiment, we studied a rodent model selected over 57 generations for high or low rates of ultrasonic vocalizations (USVs) during maternal separation as pups. We investigated the influence of this breeding on the adult animals' subsequent vocal output, comparing acoustic variables across developmental stages. We hypothesized that selection on pup USV rate would impact adult USV production without affecting lower frequency calls.

Neonatal lipopolysaccharide treatment alters hippocampal neuroinflammation, microglia morphology and anxiety-like behavior in rats selectively bred for an infantile trait.

Disruptions in homeostasis, such as the induction of inflammation, occurring during the neonatal period of development often produce changes in the brain, physiology, and behavior that persist through the life span. This study investigated the potential effects that an immune challenge delivered during neonatal development would have on anxiety behavior and stress reactivity later in life within a selectively-bred strain of rat. The rats have been bred for multiple generations to display either high or low anxiety-like phenotypic behavior.

Effects of neonatal fluoxetine exposure on behavior across development in rats selectively bred for an infantile affective trait.

Infants born to women with depressive symptoms are at higher risk for insecure attachment and behavioral problems. Thus current medical practice is to continue psychotropic medication of pregnant women with depression despite concerns about its behavioral teratology. There are few animal studies focused on long-term behavioral effects of prenatal antidepressant exposure; in addition, studies have not looked at individual differences in baseline affective state as a source of response variability.

Communal nesting exerts epigenetic influences on affective and social behaviors in rats selectively bred for an infantile trait.

Communal nesting (CN) is a mouse model of early social enrichment during pregnancy and lactation. In this study, a rat model of CN was developed to determine if CN exerts an epigenetic effect in rats selectively bred for an infantile affective trait (high and low rates of ultrasonic distress calls). High and Low offspring from CN groups were compared to standard reared (SN) offspring on five measures of social and affective behavior at three critical ages.

Comparison of two rodent models of maternal separation on juvenile social behavior.

Early childhood deprivation is associated with an increased risk of attachment disorders and psychopathology. The neural consequences of exposure to stress early in life have used two major rodent models to provide important tools for translational research. Although both models have been termed maternal separation (MS), the paradigms differ in ways that clearly shift the focus of stress between maternal and offspring units.

Effects of gestational allopregnanolone administration in rats bred for high affective behavior.

The anxiolytic neurosteroid allopregnanolone (3alpha-hydroxy-5alpha-pregnan-20-one or 3alpha,5alpha-THP) has been proposed to play a developmental role in emergent neural regulation of affective behavior. This experiment examined whether allopregnanolone administered during the last week of gestation in rats would alter neonatal and adult offspring behaviors in the selectively-bred High vocalizing line, who have low levels of allopregnanolone and high levels of anxious/depressive behaviors. Dams were injected twice a day with the neurosteroid or vehicle, or handled as controls, and were tested on the elevated plus maze just before parturition.

Olfactory association learning and brain-derived neurotrophic factor in an animal model of early deprivation.

Animal models can serve to explore neural mechanisms underlying the effects of stressful early experiences on behaviors supporting attachment. Neonatal rats primarily use olfaction for attachment, and Brain-Derived Neurotrophic Factor (BDNF) may be a key transcription target in olfactory association learning. In this experiment, neonatal male and female rats were isolated individually for 3 hr daily in the first week of life while their dams were left with partial litters (Early Deprivation, ED) or remained undisturbed (Control).

A laboratory exercise for a college-level, introductory neuroscience course demonstrating effects of housing environment on anxiety and psychostimulant sensitivity.

In this paper we describe a lab exercise developed for the Introduction to Neuroscience course at Williams College. One of a series of five labs, this exercise demonstrated several key principles of behavioral neuroscience. In this lab, students explored the effects of post-weaning housing environment on anxiety-like behavior and psychostimulant sensitivity in rodents.

The effects of selective breeding for infant ultrasonic vocalizations on play behavior in juvenile rats.

For over 25 generations, two lines of rats (High and Low USV lines) have been selectively bred for extreme rates of infantile (45 kHz) ultrasonic vocalizations (USV) in response to maternal separation at postnatal day (P)10. High and low line juveniles (P30-P40) were socially isolated and allowed to play in same-sex sibling pairs for 10 min per day over three days. Measures of play were nape contacts and pinning.

Age-dependent effects of gestational and lactational iron deficiency on anxiety behavior in rats.

Gestational iron deficiency (ID) has been linked to alterations in GABA neurotransmission, but whether these neuronal changes are mirrored in altered anxiety behavior in rats is not known. In this experiment, two tests of GABA-related affective behaviors in rats, ultrasonic vocalizations (USVs) and elevated plus maze (EPM) were used to investigate the consequences of maternal ID. Female rats were randomly assigned to one of three diet groups: low iron (10-20 ppm Fe), recommended (standard) iron control (60 ppm Fe) or lab chow (250 ppm Fe) control.

Behavioral effects of toluene in rats selectively bred for infantile vocalization rate.

Glue sniffing is epidemic among children living in poverty in Latin America. Previous research has shown that abused inhalants such as toluene share pharmacological properties with anxiolytic drugs, and that personality factors such as degree of anxiety have been proposed to modulate the effects of these drugs. To study this interaction in an animal model, rats selectively bred for high (High) or low (Low) rates of distress calls after maternal separation (ultrasonic vocalizations, USVs) were used to investigate toluene's acute and long-term effects on two measures of anxiety behavior.

Differences in affective behaviors and hippocampal allopregnanolone levels in adult rats of lines selectively bred for infantile vocalizations.

Allopregnanolone, 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-THP), a progesterone metabolite, is an endogenous neurosteroid mediating affective behaviors via its positive modulation of GABA(A) receptors. In order to better understand the role of this neurosteroid in individual differences in affective behavior, we used an animal model based on selective breeding for an infantile affective trait, ultrasonic vocalizations (USV). Adult male and female (in either proestrus or diestrus) rats that had been bred for low (low line) or high (high line) rates of USV after maternal separation were tested in a series of affective behavioral tests: open field, emergence, social interaction, defensive freezing, and the Porsolt forced swim task.

Sexually dimorphic effects of postnatal allopregnanolone on the development of anxiety behavior after early deprivation.

Stress early in life exerts persistent detrimental effects on brain development. In this experiment, a rodent model of child neglect, early deprivation (ED), was used to investigate the role of the neurosteroid allopregnanolone [AlloP; 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP)] in the development of anxiety behavior. Subjects were either undisturbed controls or ED: separated individually for 6 h per day from postnatal day (PN) 2 to 6.

Early deprivation alters the vocalization behavior of neonates directing maternal attention in a rat model of child neglect.

Animal models of child neglect (known as maternal separation or early deprivation) have suggested a causal link to subsequent depression and/or anxiety in children. In this experiment, the acoustical features of the ultrasonic calls emitted by a rat pup when separated from its dam were analyzed as well as the maternal behavior when the dam was allowed to retrieve the pup. Bout structure and harmonic double shifts did differ between controls and "neglected" pups, as did maternal attention.

Neonatal social isolation alters both maternal and pup behaviors in rats.

The development of emotional behavior is dependent on the early experiences of the infant and the quality of maternal care. In these experiments, the effects of social isolation during the preweaning period on both pup behavior and maternal responsivity were examined. In the first study, the number of ultrasonic vocalizations (USVs) emitted after brief maternal separation was measured in neonatal rats with differing histories of social isolation.

Postnatal stress of early weaning exacerbates behavioral outcome in prenatal alcohol-exposed juvenile rats.

Some of the behavioral deficits caused by prenatal or postnatal alcohol exposure have been demonstrated to be ameliorated by environmental manipulations such as handling or environmental enrichment. This experiment, in contrast, investigated whether behavioral deficits due to prenatal alcohol exposure could be exacerbated by a stressful experience, early weaning. Pregnant dams were given either a liquid diet with 35% of the calories derived from alcohol, a liquid diet without alcohol to control for any effects of the liquid diet administration, or ad libitum food and water.

Social isolation stress during the third week of life has age-dependent effects on spatial learning in rats.

Despite extensive research on the relationship between acute stress and hippocampal function in adults, little is known about the short- and long-term effects of prolonged juvenile stress on learning, memory, and other hippocampal functions. This experiment investigated whether spatial learning would be altered in juvenile and adult rats previously exposed to a chronic stressor: 6 h of social isolation (SI) daily at 15-21 days of age. SI was found to increase circulating plasma levels of corticosterone (CORT) and allopregnanolone (3-alpha,5-alpha-pregnan-20-one; 3,5-THP) at 1 h after separation on the fourth day, indicating that the isolation was an effective stressor.