Perinatal high-fat diet impairs pup retrieval and induces sex-specific changes in ultrasonic vocalization characteristics of rat pups.

Rodent pups emit ultrasonic vocalizations (USVs) to solicit maternal behavior, promoting their survival. Conversely, maternal behaviors affect the expression of pup USVs. We previously demonstrated that a maternal diet high in saturated fat (HFD) alters maternal behavior and is associated with early maturation of pups and their stress physiology. Here, we assessed the developmental profiles of pup USVs using quantitative and qualitative measures on postnatal days (PND)7 and 13. Quantitative measures included call counts, duration, and frequency, while qualitative measures examined calls' sonographic structures. HFD offspring lacked the typical decrease in USV numbers with age observed among control offspring. They also had shorter calls at PND7 compared to control and HFD offspring at PND13. HFD female offspring showed a greater number of one-frequency-sweep calls, while male pups showed a greater number of two-frequency-sweep calls compared to control offspring. Concomitantly, HFD dams showed impaired pup retrieval on PND7. The data suggest that fewer USVs of shorter duration in HFD offspring may alter dam solicitation and thus impair maternal pup retrieval. This study highlights the impacts of perinatal HFD exposure on the dyadic reciprocal interaction between dam and pups, which may set the stage for long-lasting effects on offspring physiology and behavior.

Abuaish S ，Tse EK ，McGowan PO 《-》

Effects of prenatal ethanol exposure on acoustic characteristics of ultrasonic vocalizations in rat pups.

Rat pups produce ultrasonic vocalizations (USVs) on isolation from their dam. Ultrasonic vocalization is a sensitive tool for evaluating social behavior between pups and their dam. Prenatal ethanol-exposure leads to a reduction in USVs and have the potential of inducing difficulties in social behavior between pups and their dam. However, effects of prenatal ethanol-exposure on the acoustic characteristics of USVs remain unclear. In this study, we recorded USVs produced by rat pups that were prenatally exposed to ethanol and examined their acoustic characteristics. Ethanol was administered to 13 pregnant rats in three stages by gradually increasing concentrations between gestational days (GDs) 8-20. From GDs 14-20, ethanol-containing tap water at concentrations of 30% and 15% (v/v) was administered to the high- and low-ethanol groups, respectively. Tap water without ethanol was given to the control group. On postnatal days (PNDs) 4, 8, 12, and 16, individual newly-born pups were isolated from their dam and littermates and USVs produced by them were recorded for 5 min. The number of USVs in the high-ethanol group was greater than that in both low-ethanol and control groups on PND 12. The mean, minimum, and maximum fundamental frequencies of USVs were elevated in the high-ethanol group compared with that in both low-ethanol and control groups. Higher amplitudes of USVs were produced by male pups in the high-ethanol group than in those in both low-ethanol and control groups on PND 12. These results suggest that prenatal ethanol exposure changed emotionality and accordingly, the high-ethanol group produced more USVs as distress calls.

Shahrier MA ，Wada H 《-》

Perinatal high fat diet induces early activation of endocrine stress responsivity and anxiety-like behavior in neonates.

The maternal environment has a profound effect on the development of offspring, including responses to stress mediated by the hypothalamic-pituitary-adrenal (HPA) axis. In rodents, perinatal high fat diet (HFD) has been shown to program the HPA axis in a manner that persists throughout adulthood, however the effects of perinatal HFD on stress-related behaviors and physiology in neonates are limited. The first two weeks of life in rodents are known as the stress hyporesponsive period, during which animals do not respond to stressors that are otherwise known to elicit behavioral and physiological responses in mature animals. As neonates emerge from the hyporesponsive period, the maturing neural systems mediating the HPA axis leads to the suppression of ultrasonic vocalizations (USVs) and movement in the presence of threatening stimuli, such as male adult rat odor. In this study, we investigated the effects of perinatal HFD exposure, spanning the maternal pregestation, gestation and lactation period, on stress-related behaviors and physiology in neonatal rat offspring throughout the stress hyporesponsive period. During the stress hyporesponsive period, postnatal day (PND) 7, HFD pups had higher corticosterone levels in response to the presence of male odor, produced fewer USVs, and had an increase in basal corticotropin releasing hormone (Crh) transcript levels in the paraventricular nucleus of the hypothalamus. As pup emerged from the stress hyporesponsive period, PND 13, HFD offspring exhibited higher adrenocorticotropic hormone (ACTH) levels in response to male odor, increased anxiety-like behaviors as shown by increased USVs and immobility, and lower glucocorticoid receptor (Nr3c1) transcript abundance in the ventral hippocampus. These results indicate an alteration in the typical physiological and behavioral responses to stress during the hyporesponsive period of the HPA axis as a function of perinatal HFD exposure, which involves changes in the regulation of key genes mediating the HPA axis.

Abuaish S ，Spinieli RL ，McGowan PO 《-》

Maternal high-fat diet increases independent feeding in pre-weanling rat pups.

In laboratory settings, the adult offspring of rodent dams that are maintained on high-fat diet (HFD) before conception and/or during pregnancy/lactation display an increased incidence of obese phenotypic markers, including increased body weight and adiposity, reduced leptin sensitivity, and impaired glucose tolerance. In rat pups raised by dams consuming HFD, these obese markers emerge during the first postnatal week. Since the week-old offspring of HFD dams consume excess amounts of milk during experimental tests of independent feeding (i.e., intake away from the dam), we hypothesized that maternal diet affects suckling and/or independent ingestion by pups in the home-cage environment. In the present study, this hypothesis was tested by conducting detailed analyses of ingestive behaviors expressed by pups in the home cage. Pups raised by dams consuming HFD displayed an earlier onset of independent feeding and more amounts of calorie intake from solid food during the third postnatal week compared to pups raised by dams consuming regular chow, with no diet-related differences in suckling behavior. Independent ingestion by pups in both diet groups was most frequently observed after nursing, with offspring of HFD dams engaged more frequently in post-nursing independent feeding episodes compared to offspring of chow-fed dams, particularly when the prior nursing episode was nutritive (i.e., including milk receipt by pups). We conclude that early-life exposure to HFD enhances the facilitative effect of nutritive suckling on independent feeding in pups, promoting increased caloric intake from solid food in the home-cage environment.

Kojima S ，Catavero C ，Rinaman L 《-》

Postnatal rearing environment alters pup cues for caregiver-offspring interactions.

Lapp HE ，Salazar M ，Champagne FA 《-》