Dietary preferences for feeds varying in threonine concentration by the piglet

Two choice feeding trials were carried out to investigate if weaned piglets prefer feeds varying in threonine (Thr) content. In exp 1, two control groups were fed either a 0.57% Thr (negative control) or a 0.67% Thr (positive control) feed. Two other groups had the choice from 2 feeds containing 0.57% or 0.62% Thr (Thr-choice 1) and 0.57% or 0.67% Thr (Thr-choice 2). In exp 2 the two control groups were fed either a 0.50% Thr (negative control) or a 0.62% Thr (positive control) feed and the Thr-choice groups had the choice from 2 feeds containing 0.50% or 0.56% (Thr-choice 1) and 0.50% or 0.62% Thr (Thr-choice 2), respectively. In exp 1, animals of the Thr-choice 1 showed a significant preference for the feed with the higher Thr content but in the Thr-choice 2, both feeds on offer were chosen at random. In exp 2 the preference for the higher Thr feeds in the Thr-choice groups 1 and 2 was on average 71% and 72%, respectively. In both experiments, the data of growth performance and plasma amino acid and urea pattern indicated a suboptimal Thr supply in the negative control and the Thr-choice 1 group. It is concluded that piglets are able to detect metabolic changes caused by a marginal Thr supply and that they change their feeding behaviour in order to overcome deficiency.     

Food preferences in the pigeon (Columba livia).

Pigeons offered a choice among several different types of seed presented separately in substantial quantities, show individual patterns of seed selection behavior which persist over prolonged periods. The relations among several different measures of selection were examined under a variety of presentation conditions and following experimental manipulations (food deprivation or trigeminal deafferentation) designed, respectively, to increase and decrease hunger. Different measures of selection were differentially affected by the manipulations, suggesting that they reflect the operation of different causal mechanisms. The results indicate that the pigeon's selection behavior is controlled by many of the same processes that normally control its quantitative intake.     

Perception and hedonic value of basic tastes in domestic ruminants

Taste is one of the five senses that give ruminants and other animals an awareness of their environment, especially for food selection. The sense of taste, which recognizes sweet, bitter, salty, sour and umami basic tastes, is often considered of paramount importance as it is the last sense in use before foods are swallowed. It thus plays a fundamental biological role in aiding animals to regulate intake of suitable food and reject unsuitable food. However, despite potentially relevant production and welfare issues, only a few studies have investigated how ruminants perceive and evaluate the basic tastes. Here we review current knowledge on tasting abilities and hedonic value of basic tastes in domestic ruminants via the analysis of both their anatomical and neurological structures and their behavioral preferences.Studies of the organization and functioning of the anatomical and neurological structures responsible for the perception of taste in ruminants have shown that sheep, cattle and goats all have lingual receptors for all five basic tastes. However, these studies have mainly focused on the sweet and bitter tastes. They have shown in particular that cows have fewer genes coding for the bitter receptors than other mammals, making them more tolerant to this taste. This pattern has been linked to the differences in the range of toxins and so potentially in the occurrence of bitterness encountered by different species in their environment, depending on the nature of their diet. Studies of ruminant feeding behavior have shown that the taste inducing the greatest consensus in preferences is the umami taste, with a high positive hedonic value. The bitter taste seems to have a rather negative hedonic value, the salty taste either a positive or a negative one depending on body needs, while the sweet taste seems to have a positive value in cattle and goats but not in sheep. Finally, the hedonic value of the sour taste is uncertain. Besides the hedonic value, the animal may assign a signal value to the tastes. In ruminants, the unanimous preference for the umami taste, the need dependent preference for the salty taste, and the reluctance of sheep to associate a positive reward with the bitter taste suggest that these tastes would signal the presence of proteins, minerals and toxins, respectively.     

Sex differences in behavioral taste responses to and ingestion of sucrose and NaCl solutions by rats

Sex differences in the ingestion of food and concentrated NaCl solutions by rats have been investigated for more than a quarter of a century, though the underlying mechanism(s) and the role of reproductive hormones remain the subject of debate. We hypothesized that sex differences in the ingestion of sucrose and NaCl solutions are attributable, in part, to sex differences in taste responses/taste perception. We employed short-access, 10-s tests along with 18-h, two-bottle preference tests to examine sex differences in sensitivity to and ingestion of sucrose and NaCl solutions. To evaluate the role of estrogen, we ovariectomized (OVX) female rats and then used an estrogen-replacement schedule that mimics the pattern of fluctuation of estrogen levels in intact female rats. We observed striking sex differences in the rate of licking NaCl mixed in a dilute sucrose solution. Compared to males, OVX rats with or without estrogen licked at higher rates to more concentrated NaCl solutions, suggesting that female rats are less sensitive to concentrated NaCl solutions. Although less pronounced, we also observed sex differences in the rate of licking to sucrose, particularly at lower concentrations. Compared to males, OVX rats with or without estrogen licked less, suggesting that female rats are less sensitive to lower concentrations of sucrose. Estrogen appeared to play, at most, a small role in mediating taste responses to specific concentrations of sucrose in these testing procedures. Nonetheless, sex differences in taste responses were clear, and it seems likely that such differences underlie, in part, observed differences in ingestion.     

Sweet and sour preferences in young children and adults: role of repeated exposure

We investigated the influence of repeated exposure to orangeades with added sucrose and different concentrations of citric acid, on the taste preferences of 6- to-11-year-old children and young adults. During an intervention study of 8 days, 59 children (9.2+/-0.9 years) and 46 young adults (22+/-2.0 years) received, each day, either an orangeade with a sweet taste, a sour taste, or no orangeade (control). Before (baseline) and after the intervention, preferences for a series of orangeades and yoghurt, which varied in balance of sweet and sour tastes, were measured by means of a rank-ordering procedure. The variation in balance of sweet and sour taste was established by adding different amounts of citric acid (orangeade: 0.009, 0.013, 0.020, 0.029, 0.043, and 0.065 M added citric acid; yoghurt: 0.027, 0.038, 0.056, 0.081, 0.12, and 0.17 M added citric acid) to a stock orangeade and yoghurt with 0.42 M sucrose. The sweet and sour tasting orangeade that were consumed during the intervention were equally preferred at baseline. After an 8-day exposure to the sweet orangeade, children's preferences for this orangeade (0.42 M sucrose) significantly increased (p<0.05). A similar trend was observed for the yoghurt with 0.42 M sucrose (p=0.09). An 8-day exposure to the sour orangeade did not have a significant effect on children's preference for this orangeade. The taste preferences of adults did not change after the intervention. The control group of children and adults did not show any change in preferences for sweet and sour tastes. Future research is needed to investigate whether the changed preferences for sweet taste are stable over time and how these changed taste preferences are related to a change in the consumption of sugar rich foods.     

Conditioned taste preferences in the rat induced by self-stimulation

Water-deprived rats with lateral hypothalamic electrodes were allowed to drink a novel tasting solution for 10 min, followed immediately by 15 min of intracranial self-stimulation. During a subsequent free-choice test with water, these rats exhibited a strong preference for the novel-tasting solution. Rats presented with either self-stimulation alone or the novel solution alone did not exhibit any such preference. The preference for the novel solution by the rats that experienced the pairing of this solution with self-stimulation was interpreted as a conditioned taste preference.     

Prenatal nicotine exposure transiently alters the lung mechanical response to hypoxia in young lambs

To test the hypothesis that fetal nicotine exposure alters the lung mechanical response to hypoxia (10% O(2)) 10 lambs were exposed during the last fetal trimester to a low dose nicotine (LN) and 10 to a moderate dose (MN) (maternal dose 0.5 and 1.5mg/(kgday) free base, respectively). There were 10 controls (C). At 12 days, minute ventilation increased significantly less in MN compared with LN but not with C. In contrast to C and LN, MN did not show anticipated increases in dynamic compliance, specific compliance and FRC or decrease in lung resistance but had signs of airway hyperreactivity during hypoxia. Nicotine exposure did not alter the cardiovascular response. These adverse effects decreased with advancing age. In summary, prenatal nicotine exposure alters the lung mechanical response to hypoxia. We speculate that prenatal nicotine-induced alterations of lung mechanics during hypoxia may contribute to an increased vulnerability to hypoxic stress during infancy.     

Feeding induced in cats by electrical stimulation of the brain stem

Summary Stimulation at 14 of 106 loci (Figs. 1 and 2) at which electrodes had been chronically implanted elicited immediate feeding in fully satiated, freely moving cats. Half of the effective points were in the lateral hypothalamus and thus agreed with expectations from extensive prior research on the neural organization of feeding behavior. The other points, however, were in the ventral tegmental area or at the ventrolateral boundary of the central gray. The distribution of all effective points could be explained as following a projection pathway from the globus pallidus. Exploration along 162 recording tracks in acute experiments on these same cats revealed no consistent differences in projection of evoked potentials which could distinguish stimulation at effective versus ineffective loci. Potentials of possible significance, however, were evoked in the paramedial nucleus reticularis of the medulla, the rostral pontine nuclei, the nucleus centralis superior of Bekterev, the lateral frontal cortex and the basal medial forebrain in the vicinity of the diagonal band of Broca.Supported by USPHS Grant B 1068. Dr. Wyrwicka held a fellowship from Foundations' Fund for Research in Psychiatry. The authors are indebted to Mr. Joseph Jones and Mrs. Frances Bignall for technical assistance.     

Feeding in sheep modified by intraventricular estradiol and progesterone

Estradiol benzoate given into the lateral cerebroventricle of castrate male sheep by single injections at the time of offering fresh food gave a biphasic response in the weight of food eaten in the next 30 min, with significant increases at doses of 10 and 20 μg but significant decreases at doses of 80 μg or above. Single intravenous injections of 20 to 160 μg estradiol benzoate depressed intake only from 30–60 min post injection at doses of 80 μg or more. When ventricular injections were given 1 hr after offering fresh food there was no significant effect at any of the doses tested. In two further experiments 1.88 or 1.25 mg progesterone given intraventricularly at the time of offering fresh food tended to block the intake stimulating effect of 10 or 20 μg estradiol benzoate, respectively.     

Flavor preferences conditioned by postingestive effects of nutrients in preweanling rats

The purpose of these experiments was to determine if preweanling rats, like adults, are capable of learning to associate an arbitrary flavor with the postingestive effects of nutrients, and then demonstrate a preference for that flavor after weaning. In Experiment 1, preweanlings were trained daily from postnatal day (P) 16 through P19 with intraoral (IO) infusions of a grape or cherry flavor (CS+) mixed with 20% glucose (US), and the opposite flavor (CS-) mixed with 0.05% saccharin. After weaning, rats were given a 4-h two-bottle choice between the CS+ and CS- flavors both presented in 0.05% saccharin. Rats preferred the flavor previously paired with glucose. In Experiment 2 using similar methods, rats learned to prefer a flavor (CS+G) paired with a glucose US over a flavor (CS+S) paired with a sweeter but less nutritive sucrose US, indicating involvement of postingestive reinforcement. In Experiment 3 preweanling rats with IO and intragastric (IG) catheters were trained with a CS+ flavor paired with IG nutrient infusion, and a CS- flavor paired with no IG infusion. These rats showed no flavor preference 3 days after weaning, but did significantly prefer the CS+ flavor over the CS- flavor 10 days after weaning. Together these experiments demonstrate that neural mechanisms for flavor-nutrient associations are developed before weaning, allowing young rats to learn associations between arbitrary flavors and nutritive consequences. Thus nutrient conditioning may be one way that early experience (such as flavors from the maternal diet transmitted in milk) influences later dietary preferences.     

Changes in brain cortical activity measured by EEG are related to individual exercise preferences

Exercise is well known to result in changes of brain cortical activity measured by EEG. The aim of this study was (1) to localise exercise induced changes in brain cortical activity using a distributed source localisation algorithm and (2) to show that the effects of exercise are linked to participants' physical exercise preferences.Electrocortical activity (5 min) and metabolical parameters (heart rate, lactate, peak oxygen uptake) of eleven recreational runners were recorded before and after incremental treadmill, arm crank and bicycle ergometry. Electroencephalographic activity was localised using standardised low resolution brain electromagnetic tomography (sLORETA).Results revealed an increase in frontal α activity immediately post exercise whereas increases after bike exercise were found to be localised in parietal regions. All three kinds of exercise resulted in an increase of β activity in Brodmann area 7. Fifteen and thirty minutes post exercise a specific activation pattern (decrease in frontal brain activity–increase in occipital regions) was noticeable for treadmill and bike but not arm crank exercise.We conclude that specific brain activation patterns are linked to different kinds of exercise and participants' physical exercise preferences.     

Responsiveness to methamphetamine in adulthood is altered by prenatal exposure in rats

Methamphetamine (MA) is a drug causing potent psychomotor activation. The aim of the present study was: (1) to assess the effect of prenatal and acute MA administration on behavior in adult male rats and (2) to find out if the prenatal exposure to MA increases sensitivity to acute MA application in adulthood.Behavior of adult male rats prenatally exposed to MA (5 mg/kg) or saline was tested in Open field (OF) and Elevated plus maze (EPM). Subcutaneously administered MA (1 mg/kg) or saline were used as challenge in adulthood, 30 min prior to testing.Our results showed that prenatal MA did not have an effect on baseline behavior in either of the tests. By contrast, acute MA increased overall psychomotor activity by increasing locomotion and exploratory behavior and decreasing comforting behavior. Moreover, adult rats prenatally exposed to MA exhibited increased sniffing and decreased rearing after acute MA dose in adulthood relative to prenatally saline-exposed rats. In addition, while acute MA application decreased anxiety in rats prenatally exposed to MA, rats prenatally exposed to saline were less sensitive to the anxiolytic effects of MA.Our results indicate that changes caused by prenatal exposure to psychostimulants may become apparent as different reactivity to drugs of abuse when an individual encounters them later in life. In addition, we found that the anxiolytic effect of acute MA (1 mg/kg) probably depends also on the reactivity to stress and the activity of hypothalamo-pituitary-adrenal axis.     

Swimming exercise ameliorates depression-like behaviors induced by prenatal exposure to glucocorticoids in rats

The spinal nucleus of the bulbocavernosus (SNB) in rodents is a neuromuscular system consisting of lumbar motoneurons and the perineal muscles they innervate, the bulbocavernosus and levator ani. This system is present prenatally in both males and females but degenerates postnatally in females because of the lack of perinatal androgens. Whether androgens act on the motoneurons or muscles in the SNB system to promote survival is a longstanding question. Evidence in rats suggests androgens act primarily on the muscles in development, given that the muscles express androgen receptor (AR) before the critical period of androgen-dependent cell rescue, whereas motoneurons develop AR after this period. We now report, based on a novel AR-reporter mouse model, that AR is expressed in the bulbocavernosus muscles of C57/BL6(J) mice as early as embryonic day 15, while, based on AR-immunocytochemistry, SNB motoneurons do not express AR until postnatal day 4. These results indicate that the ontogeny of AR expression in the mouse SNB system resembles that found in rats, suggesting that androgens may also act on perineal muscles in mice to rescue the SNB system.     

Swimming exercise ameliorates depression-like behaviors induced by prenatal exposure to glucocorticoids in rats

Prenatal exposure to glucocorticoids (GCs) leads to affective dysfunction in adulthood, which may be associated with the alterations in hypothalamic–pituitary–adrenal (HPA) axis. Physical exercise has been shown to ameliorate depressive symptoms. The objectives of present study were to investigate whether prenatal exposure to GCs induces depression-like behaviors in adult offspring rats, and determine whether swimming exercise alleviates the depression-like behaviors induced by this paradigm. Pregnant rats received dexamethasone (DEX) (0.1 mg/kg/day) in the last third of pregnancy or vehicle. DEX treatment reduced body weight in 1, 3, 6, 9-week old male offspring, and 3, 6, 9-week old female offspring. DEX treatment resulted in an elevated level of serum corticosterone in adult offspring (9 weeks). Female and male adult offspring rats exhibited decreased number of poking into holes and rearing and decreased central distance traveled in open field test (OFT), and reduced sucrose consumption, suggesting prenatal DEX exposure increase depression-like behaviors in the adult offspring rats. Four-week swimming exercise reduced serum corticosterone levels, and alleviated the depressive behavior by reversing the decreased number of poking into holes and rearing as well as decreased central distance traveled, and reversing the reduced sucrose consumption in male and female adult offspring. These findings suggested prenatal exposure to GCs increase the activity of HPA axis and depression-like behaviors of adult offsprings. Swimming exercise decreases HPA activity and ameliorates depression in rats exposed to DEX prenatally.     

The impairment of one-trial passive avoidance learning in chicks caused by prenatal aluminum exposure

Prenatal aluminum exposure may affect the development of the embryo and alter the capacity for learning and memory in adults. The chick embryo is a good experimental model to study the effect of prenatal toxin exposure on cognitive defects in offspring, because it eliminates maternal confounding variables. In the present study, we applied a one‐trial passive avoidance‐learning task in day‐old chicks to examine the effects of prenatal aluminum chloride injections (2, 20, and 200 mM in 200 µl per egg, daily over a period of 4 successive days) on memory consolidation. The data suggest that chicks injected with aluminum chloride (20 mM) daily from E12 to E15 had significantly impaired short‐term memory, intermediate‐term memory, and long‐term memory (LTM) after training (p < .05) but chicks injected with aluminum chloride (2 mM) had impaired LTM only. © 2011 Wiley Periodicals, Inc. Dev Psychobiol 54:133‐138, 2012.     

Sources of behavioral deviation modeled by early color preferences in quail. I. Behavioral synergism and systemic instability

Differences between population-typical norms of individual variability were studied in five genetic lines of Japanese quail (Coturnix coturnix japonica); two (BL and RL) were bidirectionally selected for early approach preference between blue and red stimuli, two (Hi and Lo) for high and low imprintabilities to the same stimuli, and the fifth (CL) was an unselected genetic control line. Selection resulted in reliably divergent extreme choice performances and imprintabilities and in progressively increasing choice variances in the BL x RL hybrids and the Hi imprintability line. Experimentation tested and rejected the hypotheses that correlated selection of synergistically acting but otherwise extraneous stimulus influences, social interaction effects, or phototactic and short-term learning effects may have been responsible for the observed large variance increases. An alternative interpretation is discussed, according to which directional selection relaxes the genetic buffering and the variance increases reflect the resulting developmental instability of the trait.This work was supported by Grant 5-R01-HD06770 from the National Institute of Child Health and Human Development, by Research Scientist Award 5-K05-MH20140 from the National Institute of Mental Health, and by The Menninger Clinic.     

舒林酸对丙戊酸孤独症动物模型大鼠氧化应激变化的影响

 目的:探讨舒林酸对孤独症发生过程中氧化应激变化的影响。方法: 利用丙戊酸（VPA）孤独症动物模型,检测经典Wnt信号通路特异性抑制剂舒林酸处理后经典Wnt信号通路及氧化应激标志物在孤独症模型大鼠前额叶皮质及海马脑区的表达变化。Western blotting法检测糖原合成激酶3β（GSK-3β）、β-catenin和4-羟基壬烯醛（4-HNE）表达,半定量RT-PCR法检测硫氧还蛋白（Trx）1和Trx2 mRNA表达。结果: 与对照组相比,在前额叶皮质及海马脑区VPA组GSK-3β蛋白表达减少,Trx1和Trx mRNA 表达减少,β-catenin与4-HNE的表达增加;而与VPA组相比,VPA与舒林酸同时处理组GSK-3β的表达显著增加,β-catenin和4-HNE的表达显著减少。结论: 舒林酸减少了孤独症发生过程中氧化应激的产生,提示经典Wnt信号通路上调导致氧化应激产生,进而导致孤独症易感性增加。     

Gender differences in behavioral changes elicited by prenatal methamphetamine exposure and application of the same drug in adulthood

The aim of the present study was to compare the response to sub‐chronic application of methamphetamine (MA) in adulthood in male and female rats prenatally exposed to the same drug. The spontaneous locomotor activity and exploratory behavior of adult male and female rats prenatally exposed to 5 mg/kg MA or saline (SAL) were tested in a Laboras apparatus (Metris B.V., Netherlands) for five consecutive days, 1 hr daily. MA 1 mg/kg or SAL were used as a challenge prior to testing. Our results showed that rats prenatally exposed to MA were more sensitive to sub‐chronic administration of MA in adulthood than prenatally SAL‐exposed rats. However, this sensitizing effect of prenatal MA exposure was manifested differently in males and females. In contrast, prenatal MA exposure decreased baseline locomotion in females. This study indicates that gender plays an important role in the sensitivity to MA during prenatal development and in adulthood. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 232–242, 2013     

丙戊酸孤独症大鼠脑中经典Wnt信号通路的变化

 目的：探讨经典Wnt信号通路在孤独症发病中的作用。方法：利用丙戊酸孤独症大鼠模型,检测经典Wnt信号通路信号分子在孤独症大鼠前额叶皮质及海马脑区的表达。Western blotting法检测糖原合成酶激酶 3β（glycogen synthase kinase 3β,GSK-3β）、磷酸化GSK-3β、β-catenin和磷酸化β-catenin表达,半定量RT-PCR法检测GSK-3β、β-catenin、c-Myc和cyclin D1 mRNA表达。结果：与对照组相比,在丙戊酸孤独症大鼠前额叶皮质及海马脑区,失活的GSK-3β磷酸化表达显著增加,抑制性的β-catenin磷酸化表达显著减少;GSK-3β mRNA表达减少,β-catenin mRNA表达增加,下游c-Myc和cyclin D1 mRNA表达增加。结论：前额叶皮质及海马中经典Wnt信号通路活性增加可能促进了机体对孤独症的易感性。