An ecologically relevant guinea pig model of fetal behavior

Abstract

The laboratory guinea pig, Cavia porcellus, shares with humans many similarities during pregnancy and prenatal development, including precocial offspring and social dependence. These similarities suggest the guinea pig as a promising model of fetal behavioral development as well. Using innovative methods of behavioral acclimation, fetal offspring of female IAF hairless guinea pigs time mated to NIH multi-colored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To insure that the ultrasound procedure did not cause significant stress, salivary cortisol was collected both before and after each observation. Measures of fetal spontaneous movement and behavioral state were quantified from video recordings from week 3 through the last week before birth. Results from prenatal quantification of Interlimb Movement Synchrony and state organization reveal guinea pig fetal development to be strikingly similar to that previously reported for other rodents and preterm human infants. Salivary cortisol readings taken before and after sonography did not differ at any observation time point. These results suggest this model holds translational promise for studying the prenatal mechanisms of neurobehavioral development, including those that may result from adverse events. Because the guinea pig is a highly social mammal with a wide range of socially oriented vocalizations, this model may also have utility for studying the prenatal origins and trajectories of developmental disabilities with social-emotional components, such as autism.

Developmental pathways of motor dysfunction

“…Recently a new longitudinal model for developmental psychobiological investigation was developed, using species relevant behavioral acclimation and a hairless strain of guinea pig (Bellinger, Lucas & Kleven, ). For this model heterozygous fetal offspring of female IAF hairless guinea pigs (Charles River, Kingston, NY) were time mated to NIH multi‐colored Hartley males (Elm Hill Labs, Chelmsford, MA) and observed longitudinally without restraint.…”

“…Observations of fetal behavior for these cross‐sectional studies included a measure of spontaneous movement known as Interlimb Movement Synchrony. Interlimb Movement Synchrony quantifies the degree of temporal association between a limb pair (e.g., right and left forelimbs), and has been shown to be a sensitive developmental measure of spontaneous movement in the fetal rat (Kleven, Lane, & Robinson, ), mouse (Kleven, Joshi, Voogd, & Ronca, ; Kleven & Ronca, ), guinea pig (Bellinger, Lucas, & Kleven, ), and even preterm human infants (Key et al, ). Interlimb Movement Synchrony is scored from video playback and quantified by 0.1 s intervals in a range from 0.0 to 0.5 s. After standardization by movement rates, the resulting profiles depict relative rates of synchronous movement.…”

“…One mammalian model using chronically instrumented sheep is already extensively implemented in longitudinal studies (Berger, Kyriakides, & Cooke, ; Karlsson, Arnardóttir, Robinson, & Blumberg, ; Nathanielsz et al, ; Robinson, Wong, Robertson, Nathanielsz, & Smotherman, ), but may be limited in use for the study of Developmental Pathways due to the size and cost of the species. Recent advances in ultrasound technology, however, have made possible the addition of longitudinal study with smaller mammals such as guinea pigs (Bellinger, Lucas, & Kleven, ; Cohen et al, ; van Kan, de Vries, Luchinger, Mulder, & Taverne, ).…”

“…To confirm that the ultrasound and handling procedures did not cause significant stress, salivary cortisol was collected both before and after each observation. Salivary cortisol readings did not differ at any observation time point (Bellinger, Lucas, & Kleven, ). Due to the small litter size of the IAF guinea pig (2–3 pups) fetal offspring that have been observed with prenatal ultrasound are easily identified at birth.…”

“…Microgenetic designs, particularly at time points of rapid change, may be necessary (Siegler & Chen, 1998). For example, recent quantification of the patterns of movement in fetal guinea pigs has identified early organization of behavioral states almost from the inception of movement (Bellinger, Lucas, & Kleven, ). These changes take place rapidly, perhaps over a period of only 1 day (van Kan et al, ).…”