Body composition and behaviour in adult rats are influenced by maternal diet, maternal age and high-fat feeding

Fetal exposure to maternal undernutrition has lifelong consequences for physiological and metabolic function. Maternal low-protein diet is associated with an age-related phenotype in rats, characterised by a period of resistance to development of obesity in early adulthood, giving way to an obesity-prone, insulin-resistant state in later adulthood. Offspring of rats fed a control (18 % casein) or low-protein (9 % casein; LP) diet in pregnancy were challenged with a high-fat diet at 9 months of age. To assess whether other maternal factors modulated the programming effects of nutrition, offspring were studied from young (2–4 months old) and older (6–9 months old) mothers. Weight gain with a high-fat diet was attenuated in male offspring of older mothers fed LP (interaction of maternal age and diet; P = 0·011) and adipose tissue deposition was lower with LP feeding in both males and females (P < 0·05). Although the resistance to weight gain and adiposity was partially explained by lower energy intake in offspring of LP mothers (P < 0·001 males only), it was apparent that energy expenditure must be influenced by maternal diet and age. Assessment of locomotor activity indicated that energy expenditure associated with physical activity was unlikely to explain resistance to weight gain, but showed that offspring of older mothers were more anxious than thoseof younger mothers, with more rearing observed in a novel environment and on the elevated plus-maze. The data showed that in addition to maternal undernutrition, greater maternal age may influence development and long-term body composition in the rat

Food Deprivation, Body Weight Loss and Anxiety-Related Behavior in Rats

In behavioral studies, food deprivation protocols are routinely used to initiate or maintain motivational states that are required in a particular test situation. However, there is limited evidence as to when food deprivation compromises animal welfare. This study investigated the effects of different lengths of food deprivation periods and restricted (fixed-time) feeding on body weight loss as well as anxiety-related and motivated behavior in 5–6 month old male and female Wistar rats. The observed body weight loss was not influenced by sex and ranged between 4% (16 h deprivation) to approximately 9% (fixed-time feeding). Despite significant body weight loss in all groups, the motivation to eat under the aversive test conditions of the modified open field test increased only after 48 h of food deprivation. Long-lasting effects on anxiety as measured in the elevated plus maze test 24 h after refeeding have not been observed, although fixed-time feeding could possibly lead to a lasting anxiogenic effect in female rats. Overall, female rats showed a more anxiolytic profile in both tests when compared to male rats. Despite these sex differences, results suggest that food deprivation is not always paralleled by an increased motivation to feed in a conflict situation. This is an important finding as it highlights the need for tailored pilot experiments to evaluate the impact of food deprivation protocols on animals in regard to the principles of the 3Rs introduced by Russell and Burch. View Full-Tex

The impact of cafeteria feeding during lactation in the rat on novel object discrimination in the offspring

There is increasing evidence that hyperenergetic diets impact on memory in rodents. However, it is largely unknown how diets, such as a cafeteria diet (CD), that mimic a Western diet act on learning and memory, in particular when fed during early stages of development. Here, we fed lactating dams a cafeteria diet and exposed both male and female offspring to a novel object discrimination (NOD) task, a two-trial test of recognition memory in which rats exposed to two identical objects during a training/familiarisation trial can discriminate a novel from a familiar object during the subsequent choice trial. The choice trial was performed following inter-trial interval (ITI) delays of up to 4 h. Maternal diet did not impact on exploration of the objects by either sex during the familiarisation trial. Control males discriminated the novel from the familiar object indicating intact memory with an ITI of 1h, but not 2 or 4h. CD delayed this natural forgetting in male rats such that discrimination was also evident after a 2h ITI. In contrast, control females exhibited discrimination following both 1 and 2h ITIs, but CD impaired performance. In summary, the present study shows that maternal exposure to CD programmes NOD in the adult. In better performing females dietary programming interferes with NOD whereas NOD was improved in males after lactational CD feeding

Dopamine D1-like receptor signalling in the hippocampus and amygdala modulates the acquisition of contextual fear conditioning

RATIONALE: Dopamine D1-like receptor signalling is involved in contextual fear conditioning, but the brain regions involved and its role in other contextual fear memory processes remain unclear. OBJECTIVES: The objective of this study was to investigate (1) the effects of SCH 23390, a dopamine D1/D5 receptor antagonist, on contextual fear memory encoding, retrieval and reconsolidation, and (2) if the effects of SCH 23390 on conditioning involve the dorsal hippocampus (DH) and/or basolateral amygdala (BLA). METHODS: Rats were used to examine the effects of systemically administering SCH 23390 on the acquisition, consolidation, retrieval and reconsolidation of contextual fear memory, and on locomotor activity and shock sensitivity. We also determined the effects of MK-801, an NMDA receptor antagonist, on contextual fear memory reconsolidation. The effects of infusing SCH 23390 locally into DH or BLA on contextual fear conditioning and locomotor activity were also examined. RESULTS: Systemic administration of SCH 23390 impaired contextual fear conditioning but had no effects on fear memory consolidation, retrieval or reconsolidation. MK-801 was found to impair reconsolidation, suggesting that the behavioural parameters used allowed for the pharmacological disruption of memory reconsolidation. The effects of SCH 23390 on conditioning were unlikely the result of any lasting drug effects on locomotor activity at memory test or any acute drug effects on shock sensitivity during conditioning. SCH 23390 infused into either DH or BLA impaired contextual fear conditioning and decreased locomotor activity. CONCLUSIONS: These findings suggest that dopamine D1-like receptor signalling in DH and BLA contributes to the acquisition of contextual fear memory

Exposure to a maternal cafeteria diet changes open-field behaviour in the developing offspring

The early postnatal period is a sensitive period in rodents as behavioural systems are developing and maturing during this time. However, little is currently known about the behavioural effects of feeding a hyper-energetic cafeteria diet (CD) during the lactational period when offspring behaviour is tested during early adolescence. To this end, 23 days old offspring from dams (Wistar) fed on CD during lactation were tested in either the open-field or the elevated plus-maze for exploration and anxiety-related behaviour. On postnatal day 9, maternal behaviour and non-maternal behaviour of the dam was assessed. It was hypothesized that lactational CD feeding would reduce anxiety in the offspring. CD-fed dams had a higher energy intake, due to an overconsumption of sugars and fats. When offspring from these dams were exposed to the open field after weaning, their locomotor activity was increased. They entered the more aversive inner zone of the open-field after a shorter latency, made more entries into and spent more time in the inner zone. Anxiety-related behaviour was not affected upon exposure to the elevated plus maze, suggesting anxiolysis in the open-field only. Increased maternal licking/grooming behaviour could possibly contribute to the anxiolytic phenotype as observed in the offspring from the CD group. In conclusion, we demonstrate that lactational overfeeding impacts on the development of behaviour in the early adolescent rat

Concept Study of a fast VTOL-UAV Technology-Demonstrator for MUM-T

The Manned Unmanned Teaming (MUM-T) of rotorcraft offers the potential to increase the effectivity and survivability of the combined tactical unit. Currently, commercially available Unmanned Aerial Vehicles (UAVs) with Vertical Take-Off and Landing (VTOL) capability are not specifically designed for fast forward flight and would slow down the entire tactical unit. This study presents the first results of the development of a technology-demonstrator with a maximum airspeed of at least 180 kt. The investigation of different VTOL-UAV concepts, the selection of a thrust-compound configuration and the first details of the predesign are described. Furthermore, the flight performance is analyzed with focus on maximum airspeed, power, endurance and range. The results show, that the proposed design of the VTOL-UAV is expected to fulfill the requirements

Early postnatal exposure to a cafeteria diet interferes with recency and spatial memory, but not open field habituation in adolescent rats

The cafeteria diet (CD), an experimental diet that mimics the obesogenic Western diet, can impair memory in adult rats. However, the suckling period is also particularly susceptible to diet‐induced behavioural modification. Here, following exposure to CD feeding during lactation, 24‐ to 26‐day‐old offspring were tested to determine maternal dietary effects on either open field habituation, object location (OL) learning or on recency learning. Whereas no impact on habituation learning could be demonstrated, both OL and recency memory were impaired. In controls (C), OL memory was shown both after a 5 min (p < .05) or 60 min (p < .001) inter‐trial interval (ITI). After the 60 min ITI, the difference between C and CD was significant (p < .05). Learning did not occur in the CD group at any time point and was not observed after the 24hr ITI in in either group. Whereas control rats demonstrated intact recency memory (p < .00001), no learning occurred in the CD group. Both groups differed significantly in their exploration ratios (p < .01). This study suggests a detrimental effect of exposure to an unhealthy Western diet during lactation, on cognitive functions in adolescent rats. These results could have implications for human cognition in the context of obesity epidemic

The impact of early postnatal environmental enrichment on maternal care and offspring behaviour following weaning

The early postnatal period is a sensitive period in rodents as behavioural systems are developing and maturing during this time. However, relatively little information is available about the impact of environmental enrichment on offspring behaviour if enrichment is implemented only during this period. Here, environmental enrichment was provided from postnatal day 1 until weaning. On post-natal day 9, maternal behaviour and nonmaternal behaviour of the dam was observed. Nursing time in the enriched group was reduced but dams showed more non-maternal appetitive behaviours. Offspring were exposed to either the open field or the elevated plus maze (EPM) after weaning. In the open field, rats from the enriched group approached the more aversive inner zone of the open field later than control rats. Offspring from the enriched group made fewer entries into the inner zone and spent less time in this part of the arena. Enrichment had no impact on behaviour in the EPM. The present study provides evidence that postnatal enrichment can interfere with maternal behaviour in rats and can possibly lead to increased anxiety in the offspring. The findings suggest that enrichment procedures can have potentially unintended effects, interfering with the development of emotional behaviours in rats

The impact of cafeteria diet feeding on physiology and anxiety-related behaviour in male and female Sprague-Dawley rats of different ages

There is emerging experimental evidence that hyper-energetic diets not only cause obesity but also impact on behaviour in rodents. A hyper-energetic comfort diet/cafeteria diet (CD) fed during early development programmes anxiety-related behaviour in adult age, but little is known how an obesogenic CD impacts on behaviour when fed at a later age. To this end we fed CD to Sprague-Dawley rats of both sexes at either 6 weeks or 12 months old, for a period of 6 weeks. Anxiety-related behaviour was assessed in the elevated plus maze (EPM) and the open field (OF). A glucose tolerance test was performed and metabolic indices, body weight and fat were measured. CD-fed young adult females, but not males, had a higher energy intake, due to an overconsumption of carbohydrates and fats. Only in adult CD-fed rats of both sexes did this overconsumption led to increased weight gain. Protein intake was reduced in all CD groups. Fat mass (subcutaneous, perirenal, gonadal) increased in most CD groups, whereas brown fat increased only in adults. Triacyglycerol, free fatty acid and total cholesterol concentrations increased predominantly in adult CD-fed rats. Glucose tolerance was only impaired in adult males. CD-fed adult males showed fewer entries into the aversive open arms and groomed more on the EPM, whereas adult females spent more time on these arms. In the OF, CD-fed females of both ages visited the inner zone more frequently and travelled a longer distance. The behavioural data suggests anxiolysis in CD-fed females and signs of increased anxiety in adult males. In conclusion, this study demonstrates that feeding CD leads to both obesity and behavioural changes in rats. Overall, these effects were more pronounced in older rats, with the behavioural effects being particularly gender dependent