Adolescence Predatory Risk Alters Social Behaviors and Cognitive Ability and Central Oxytocin and Vasopressin Expression in Adult Brandt's Voles.

INTRODUCTION: Stress during adolescence causes long-term behavioral changes in adulthood. We previously found that adolescent exposure to predatory risk augments adolescent social contact and adult parental behavior in Brandt's voles (Lasiopodomys brandtii). METHODS: Here, we determined whether this experience alters sexual behavior, pair-bond formation, and recognition ability as well as basal HPA axis activity, central oxytocin (OT), and arginine-vasopressin (AVP) expression in adulthood. RESULTS: In the social interaction test, repeated cat odor (CO) exposure enhanced the frequency of lordosis by female voles toward an unfamiliar opposite-sex conspecific. CO voles preferred to engage with their partners after 48-h cohabitation whereas the control groups did not, which may reflect stable pair bonds in the CO treatment group. Furthermore, adolescent exposure to CO inhibited novel object recognition and place recognition ability, while it influenced social recognition only among adult males. No effect of adolescent CO exposure was observed for basal HPA axis activity, showing a habituation effect. Finally, we found that CO exposure increased OT and decreased AVP expression in the hypothalamus, including the paraventricular nucleus and anterior hypothalamus. The levels of OT in the medial amygdala were lower, and AVP in the lateral septum was higher in CO voles compared with the control. CONCLUSION: These findings demonstrate that adolescent exposure to predator risk promotes adult reproductive behavior of Brandt's voles. Deficits in recognition ability may necessitate alterations in reproductive strategies to enhance inclusive fitness. OT and AVP systems may play a modulatory role in the alteration of social behaviors elicited by adolescent predatory risk.

Interspecific differences in sociability, social novelty preference, anxiety- and depression-like behaviors between Brandt's voles and C57BL/6J mice.

The three-chamber test has been widely used to investigate social approach/novelty preference in rodents. Most studies have used the briefly familiar and unfamiliar individuals as stimuli to examine social recognition; however, little is known about the effects of long-term familiar peers in this paradigm. In the present study, we made a slight modification to it: the first phase measured preference for a cage-mate (not a novel individual) over an identical wire cage without an individual stimulus; the later phase measured preference for a novel individual placed in the previous empty wire cage compared to the cage-mate (not the briefly familiar individual). The present study aimed to compare differences in sociability and social recognition between Brandt's voles (Lasiopodomys brandtii) and C57BL/6J mice using this modified three-chamber test. The levels of anxiety-, depression-, and anhedonia-like behaviors were also examined in both species. We found that Brandt's voles preferred the cage-mate over the empty cage in phase 1 and showed a preference for the novel individual in phase 2. In C57BL/6J mice, males showed no preference for familiar peers in phase 1, whereas females failed to show a preference for the novel individual in phase 2, showing a sex-specific difference. Furthermore, Brandt's voles displayed higher levels of locomotor activity and sociability as well as lower levels of anxiety-, depression-, and anhedonia-like behaviors than C57BL/6J mice. Interestingly, sociability and social approach correlated with depression-like behavior, whereas social novelty preference correlated with anhedonia-like behavior. Together, these data indicate that Brandt's voles and C57BL/6J mice show significant differences in sociability, social recognition, and levels of anxiety- and depression-like behaviors. Furthermore, Brandt's voles are more suitable for the study of selective social relationships.

Postpartum maternal exposure to predator odor alters offspring antipredator behavior, basal HPA axis activity and immunoglobulin levels in adult Brandt's voles.

Predation risk can program offspring behavior, physiology, and fitness through maternal effect, but most studies have mainly focused on this effect during pregnancy; little is known about the effect of postpartum predation risk on offspring's phenotype. Here, we compared the antipredator behaviors of adult offspring (approximately 90 days old) produced by female Brandt's voles (Lasiopodomys brandtii) exposed to one of three treatments: cat odor (CO), rabbit odor (RO), and distilled water (DW) for 60 min daily from postpartum day 1-18. Basal levels of plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT), hypothalamic corticotrophin releasing hormone (CRH), as well as spleen immunoglobulins (IgA, IgM, and IgG) were also measured. Our data showed that the offspring of CO-exposed mothers displayed less head-out behavior to acute 15-min CO exposure, and female offspring showed more freezing behavior. CO offspring showed significantly lower basal ACTH and CORT levels than the RO and DW offspring. Additionally, female but not male CO offspring had higher hypothalamic CRH expression and spleen IgG levels than controls, showing a sex-specific effect. These findings demonstrate that postpartum maternal predator risk exposure promotes a passive-avoidant response to these cues in adult offspring, showing a cross-generational maternal effect of postpartum predation risk. Further, these changes may be associated with alterations in the hypothalamic-pituitary-adrenal axis and immune function.

Effects of wheat flour particle size on flour physicochemical properties and steamed bread quality.

In this study, differently sized particles of wheat flour (from 52.36 µm to 108.89 µm) were obtained by adjusting the distance between the rolls (0.02, 0.04, 0.06, 0.08, and 0.1 mm) of a heart mill. Results showed that reducing the particle size significantly increased the damaged starch (DS) content. Uniaxial tensile measurement of dough showed that reducing the particle size of wheat flour can effectively increase the maximum tensile resistance, but the extensibility reaches the maximum in samples at medium particle diameter (78 and 66 µm). Additionally, the ratio of dynamic moduli (G″/G') decreased with a reducing particle size. The results of disulfide bond content, gluten microstructure, showed that finer flour granulation can strengthen the gluten network. The steamed bread (SB) making test showed that SB made from wheat flour of a smaller particle size had a significantly smaller specific volume than that made from a larger particle size. The texture profile analysis showed that with a decrease of wheat flour particle size, the hardness, chewiness of SB increased, the resilience decreased, and there was no significant difference in adhesiveness. Overall, the quality of SB made flour of medium particles (78 µm) is better.

Effects of vacuum degree, mixing speed, and water amount on the moisture distribution and rheological properties of wheat flour dough.

Effects of vacuum degrees (0.00, 0.02, 0.04, 0.06, 0.08 MPa) on water distribution state, tensile properties, stress relaxation properties, and viscoelasticity of dough, as well as the effects of mixing speed (50, 70, 90 rpm/min) and water content (40%, 45%, 50%) under optimum vacuum degree were studied. The results showed that the proper vacuum degree (0.06 MPa) could promote the full contact between flour and water and improved the water-holding capacity of the dough. Meanwhile, the dough had stronger tensile strength, the best viscoelasticity and the ability to recover from external deformation more quickly. Under the vacuum of 0.06 MPa, with the increasing of mixing speed, the response to the external force of dough increased first and then decreased. Adding more water reduced the strength of dough, weakened the response to external forces, and led to a significant decrease in tensile resistance and tensile area of the dough, as well as a decrease in viscoelasticity (p < 0.05). The proper vacuum mixing allowed the preparation of dough to require more water and less energy. PRACTICAL APPLICATION: In the processing of wheat flour products, vacuum mixing is considered to be beneficial to the quality of noodles and breads. As the intermediate of these products, the dough is of great significance for the monitoring of its rheological characteristics. In this study, a moderate vacuum degree led to a significant improvement in the rheological properties of the dough, and the processing performance was the best. Under the optimal vacuum degree, the influence of mixing speed and water amount cannot be ignored. Vacuum mixing is an efficient dough preparation method, which can produce certain economic benefits.

Effects of wheat flour particle size on physicochemical properties and quality of noodles.

The effect of particle size on the physicochemical and noodle quality of wheat flours was investigated. Granular wheat flour was ground by adjusting the distance between the rolls (0.02, 0.04, 0.06, 0.08, and 0.1 mm) of the flour mill to obtain wheat flour in five different particle sizes. The results showed that milling intensity significantly reduced the particle size and increased the damaged starch content and sedimentation value, but there were no significant differences in protein or ash contents. The reduction of wheat flour particle size significantly decreased the peak viscosity, trough viscosity, final viscosity, breakdown, and setback of the blends, while there were no significant differences in pasting temperature. Stress relaxation characteristics indicated that as the particle size of wheat flour decreased, dough hardness increased. The noodles made from wheat flour with a smaller particle size had a higher water absorption rate and cooking loss rate. Textural profile analysis parameters showed that as the particle size of wheat flour decreased, the hardness, chewiness, recovery, and adhesiveness of noodles showed increasing trends, and there was no significant difference in elasticity. In summary, it is found that the quality of the noodles made by sample C (D50 : 78.47 µm) is better.

Ultrafine grinding of wheat flour: Effect of flour/starch granule profiles and particle size distribution on falling number and pasting properties.

In the present paper, the properties of different ultrafine flour samples, including particle size distribution, damaged starch content, falling number, and pasting properties, were examined. The results indicated that the particle size decreased significantly after jet milling, as the rotation speed and grinding time increased, and the damaged starch content significantly increased as the size of the flour/starch decreased; this is in contrast to the significant decrease in falling number. Significant differences in pasting temperature were observed between straight-grade flour (68.6°C) and five ultrafine flour samples (from 86.3 to 87.9°C). We also observed significant increases in peak viscosity, trough, breakdown viscosity, final viscosity, and setback as the flour particle size decreased from 43.07 µm to 25.81 µm (D50). The same parameters significantly decreased as the flour particle size decreased from 25.81 µm to 10.15 µm (D50). Correlation analysis identified a significant negative correlation between flour particle size (D50) and damaged starch content and pasting temperature, while a significant positive correlation was found with the falling number values. The results of this work may have an important impact on the quality of processed foods.