Oxytocin (OT) and arginine-vasopressin (AVP) act on OT receptors and not AVP V1a receptors to enhance social recognition in adult Syrian hamsters (Mesocricetus auratus)

Social recognition is a fundamental requirement for all forms of social relationships. A majority of studies investigating the neural mechanisms underlying social recognition in rodents have investigated relatively neutral social stimuli such as juveniles or ovariectomized females over short time intervals (e.g., 2 h). The present study developed a new testing model to study social recognition among adult males using a potent social stimulus. Flank gland odors are used extensively in social communication in Syrian hamsters and convey important information such as dominance status. We found that the recognition of flank gland odors after a 3 min exposure lasted for at least 24 h, substantially longer than the recognition of other social cues in rats and mice. Intracerebroventricular injections of OT and AVP prolonged the recognition of flank gland odor for up to 48 h. Selective OTR but not V1aR agonists, mimicked these enhancing effects of OT and AVP. Similarly, selective OTR but not V1aR antagonists blocked recognition of the odors after 20 min. In contrast, the recognition of non-social stimuli was not blocked by either the OTR or the V1aR antagonists. Our findings suggest both OT and AVP enhance social recognition via acting on OTRs and not V1aRs and that the recognition enhancing effects of OT and AVP are limited to social stimuli.     

Perinatal effects of exposure to PCBs on social preferences in young adult and middle-aged offspring mice

In social species, social interactions between conspecifics constitute a fundamental component to establish relations, provide best chances to reproduce, and even improve survival rates. In this study, a three-chambered social approach test was used to estimate the level of sociability and level of preference for social novelty in both male and female young adult (postnatal day (PND) 50) and middle-aged (PND 330) offspring mice (n = 10 per group) that were perinatally exposed to a mixture of six polychlorinated biphenyls (PCBs), 28, 52, 101, 138, 153, and 180, at environmentally low doses (10 and 1000 ng/kg b.w. for dams during gestation and lactation), a profile that closely mimics human exposure to contaminated fish. Our results showed that PCBs bidirectionally modulated social preferences in offspring mice, and the effects were sex and age dependent. However, increased levels of social interactions were rather frequently detected in both assays of the three-chambered test. Reduced social interaction was only induced in 1000 ng/kg PCB-exposed middle-aged males, which exhibited similar preferences to social and non-social stimuli when compared to middle-aged controls. Furthermore, results showed that plasma levels of both corticosterone and acetylcholinesterase activity were higher in all PCB-exposed middle-aged males and females than in their control counterparts. In summary, although the effects of PCBs were only of moderate magnitude, our results suggest that a PCB mixture can act as an endocrine disruptor in offspring mice, disturbing the formation of normal social habits.     

Protective effect of oxytocin on ovarian ischemia-reperfusion injury in rats

Oxytocin (OT), a neurohypophysial nonapeptide, plays dual role as a neurotransmitter/neuromodulator and a hormone. It has also well known protective properties against ischemia/reperfusion organ damage. This study investigated the effect of OT on experimentally induced ovarian torsion/de-torsion ischemia/reperfusion (I/R) injury in rats. Sprague-Dawley rats were assigned to five treatment groups (n = 7/group): Group 1, sham-operated; Group 2, torsion; Group 3, 80 IU/kg of OT administration 30 min prior to torsion; Group 4, torsion/de-torsion; and Group 5, torsion followed by 80 IU/kg of OT administration 30 min prior to de-torsion. OT administration significantly decreased the tissue malondialdehyde (MDA) levels in both the torsion and OT group (Group 3), and torsion/de-torsion OT group (Group 5) in comparison with the torsion-only group (Group 2) and torsion/de-torsion group (Group 4). Histopathological finding scores including follicular degeneration, edema, hemorrhage, vascular congestion, and infiltration by inflammatory cells were found to be significantly decreased in the torsion and OT group (Group 3), and torsion/de-torsion OT group (Group 5) when compared with the torsion-only group (Group 2) and torsion/de-torsion group (Group 4). In conclusion, these results, verified with histopathologic evaluation and biochemical assays, suggest a probable protective role for OT in ischemia and I/R injury in rat ovaries.     

Testosterone may increase selective attention to threat in young male macaques

Animal studies indicate that sex hormones have widespread effects on the brain, cognition and emotion, but findings in humans are inconsistent. Well-controlled studies in nonhuman primates are crucial to resolve these discrepancies. In this study, we examined the effects of testosterone (T) on emotion in male rhesus monkeys. Six young adult males were tested on two emotional tasks during three hormonal conditions in a crossover design: when intact at baseline and when pharmacologically hypogonadal with add-back of T or placebo. The emotional tasks were the Approach–Avoidance task, which tested behavioral responses to three categories of objects (familiar, novel, and negative) and a Social Playback task which tested behavioral responses to scenes of unfamiliar conspecifics engaged in three types of social activities (neutral, positive, or negative). Following a 4-week baseline period, monkeys were treated with Depot Lupron, 200 μg/kg before being randomly assigned to one of two treatment groups: Depot Lupron + Testosterone Enanthate (TE, 20 mg/kg) or Depot Lupron + oil vehicle. In each treatment group, monkeys received one injection of Lupron and one injection of TE or one injection of Lupron and one injection of oil at the onset of a 4-week testing period, before crossing over to the alternate treatment for an additional 4 weeks of testing. TE treatment had no effect on behavioral measures in the Approach–Avoidance task. For the Social Playback task, however, TE significantly increased watching time of video clips which depicted fights between unfamiliar conspecifics. The enhancing effect of T on watching time for negative social scenes is consistent with human data suggesting that T decreases aversion or facilitates approach to threatening social stimuli. Further studies are needed to understand the mechanisms by which T may mediate responsiveness to social threat in male primates.     

The effects of prenatal PCBs on adult social behavior in rats

Endocrine disrupting chemical (EDC) exposures during critical periods of development may influence neuronal development and the manifestation of sexually dimorphic sociability and social novelty behaviors in adulthood. In this study, we assessed the effects of gestational exposure to PCBs on the social behavior of males and females later in adulthood. A weakly estrogenic PCB mixture, Aroclor 1221 (A1221, 0.5 or 1 mg/kg) was administered to pregnant Sprague–Dawley rat dams. Both a positive control (estradiol benzoate; EB, 50 μg/kg) and negative control (dimethylsulfoxide; DMSO in sesame oil vehicle) were similarly administered to separate sets of dams. The sexes responded differently in two tasks essential to sociality. Using a three-chamber apparatus that contained a caged, same-sex, gonadectomized stimulus animal and an empty stimulus cage, we found that both sexes showed a strong preference for affiliating with a stimulus animal (vs. an empty cage), an effect that was much more pronounced in the males. In the second task, a novel and a familiar stimulus animal were caged at opposite ends of the same apparatus. Females displayed a higher degree of novelty preference than the males. During both tests, females had significantly higher social approach behaviors while male engaged in significantly more interactive behaviors with the conspecific. Of particular interest, males born of dams that received prenatal A1221 (0.5 mg/kg) exhibited an overall decrease in nose-to-nose investigations. These behavioral data suggest that the males are more sensitive to A1221 treatment than are females. In addition to behavioral analysis, serum corticosterone was measured. Females born of dams treated with A1221 (0.5 mg/kg) had significantly higher concentrations of corticosterone than the DMSO female group; males were unaffected. Females also had significantly higher corticosterone concentrations than did males. Overall, our results suggest that the effects of gestational exposure to PCBs on adult social behavior are relatively limited within this particular paradigm.     

Oxytocin inhibits pentylentetrazol-induced seizures in the rat

We aimed to reveal the anti-convulsant effects of oxytocin (OT) in pentylenetetrazol (PTZ)-induced seizures in rats. Thirty rats were randomly divided into 5 equal groups. Using stereotaxy, we implanted electroencephologram (EEG) electrodes in the left nucleus of the posterior thalamus. After 2 days, the first and second groups were used as the control and PTZ (35 mg/kg) groups, respectively. We administered 40, 80 and 160 nmol/kg OT + 35 mg/kg PTZ to the rats, constituting the third, fourth, and fifth groups, respectively, for 5 days. At the end of 5 days, we recorded EEGs via bipolar EEG electrodes. After 12 h, all groups except the first received 70 mg/kg PTZ and we determined the dose–response ratio. Racine's Convulsion Scale was used to evaluate seizures. The spike–wave complex percentage in the EEG was determined as 0% for the first group, 38.6% ± 7.2 for the second group, 36.4% ± 5.6 for the third group, 4.3% ± 1.8 for the fifth group and 4.1% ± 1.1 for the fifth group. The fourth and fifth groups had significantly decreased spike–wave complex percentages compared to the second group (p < 0.0001). OT may prevent PTZ-induced epilepsy on an EEG. OT may also be considered for use in the treatment of epilepsy in the future.     

Combining oxytocin administration and positive emotion inductions: Examining social perception and analytical performance

Intranasal administration of the hypothalamic neuropeptide oxytocin (OT) has, in some studies, been associated with positive effects on social perception and cognition. Similarly, positive emotion inductions can improve a range of perceptual and performance-based behaviors. In this exploratory study, we examined how OT administration and positive emotion inductions interact in their associations with social and analytical performance. Participants (N = 124) were randomly assigned to receive an intranasal spray of OT (40 IU) or placebo and then viewed one of three videos designed to engender one of the following emotion states: social warmth, pride, or an affectively neutral state. Following the emotion induction, participants completed social perception and analytical tasks. There were no significant main effects of OT condition on social perception tasks, failing to replicate prior research, or on analytical performance. Further, OT condition and positive emotion inductions did not interact with each other in their associations with social perception performance. However, OT condition and positive emotion manipulations did significantly interact in their associations with analytical performance. Specifically, combining positive emotion inductions with OT administration was associated with worse analytical performance, with the pride induction no longer benefiting performance and the warmth induction resulting in worse performance. In sum, we found little evidence for main or interactive effects of OT on social perception but preliminary evidence that OT administration may impair analytical performance when paired with positive emotion inductions.     

A functional MRI study on how oxytocin affects decision making in social dilemmas: Cooperate as long as it pays off,aggress only when you think you can win

We investigate if the neuropeptide oxytocin (OT), known to moderate social behaviour, influences strategic decision making in social dilemmas by facilitating the integration of incentives and social cues. Participants (N = 29) played two economic games with different incentive structures in the fMRI scanner after receiving OT or placebo (following a double blind, within-subject design). Pictures of angry or neutral faces (the social cues) were displayed alongside the game matrices. Consistent with a priori hypotheses based on the modulatory role of OT in mesolimbic dopaminergic brain regions, the results indicate that, compared to placebo, OT significantly increases the activation of the nucleus accumbens during an assurance (coordination) game that rewards mutual cooperation. This increases appetitive motivation so that cooperative behaviour is facilitated for risk averse individuals. OT also significantly attenuates the amygdala, thereby reducing the orienting response to social cues. The corresponding change in behaviour is only apparent in the chicken (or anti-coordination) game, where aggression is incentivized but fatal if the partner also aggresses. Because of this ambiguity, decision making can be improved by additional information, and OT steers decisions in the chicken game in accordance with the valence of the facial cue: aggress when face is neutral; retreat when it is angry. Through its combined influence on amygdala and nucleus accumbens, OT improves the selection of a cooperative or aggressive strategy in function of the best match between the incentives of the game and the social cues present in the decision environment.     

The sexual preference of female rats is influenced by males' adolescent social stress history and social status

Ongoing development of brain systems for social behaviour renders these systems susceptible to the influence of stressors in adolescence. We previously found that adult male rats that underwent social instability stress (SS) in mid-adolescence had decreased sexual performance compared with control males (CTL). Here, we test the hypotheses that SS in adolescence decreases the “attractiveness” of male rats as sexual partners compared with CTL rats and that dominance status is a protective factor against the effects of SS. The main prediction was that females would spend more time with CTL males than SS males, and that this bias would be greater for submissive than for dominant rats. Among dominant pairs (n = 16), females preferred SS males, spending more time with and visiting more often SS than CTL males (each pair tested 5 ×), and SS males had shorter latencies to ejaculation, shorter inter-ejaculation intervals, and made more ejaculations compared with CTL males. Among submissive pairs (n = 16), females spent more time with, visited more often, and displayed more paracopulatory behaviour with CTL than with SS males, and differences in sexual performance between SS and CTL males were modest and in the opposite direction from that in dominant pairs. The heightened motivation of SS males relative to CTL males for natural rewards may have attenuated differences in sexual performance in a paced mating context. In sum, the experience of stress in adolescence leads to long-lasting changes in males that are perceptible to females, are moderated by social status, and influence sexual behaviour.     

Effects of short- and long-term changes in spatial density on the social behavior of captive chimpanzees (Pan troglodytes)

The constraints of captivity may often require non-human primates to experience restrictions in space for both long- and short-term periods of time. The tension-reduction model predicts that great apes should increase affiliative behaviors and decrease aggressive behaviors as a coping strategy. The conflict avoidance model, however, predicts that great apes should decrease all social interactions (affiliative and aggressive) as a coping strategy. The purpose of this study was to test the conflict-avoidance and tension-reduction models by examining the effects of both short-term (1–2 days) and long-term (6 months) changes in spatial density on social behavior in 23 adult captive chimpanzees (6 males, 17 females) housed at the Primate Foundation of Arizona. Affiliative (i.e., social groom, social play) and agonistic (i.e., charging display, attack) were assessed using scan-sampling techniques while subjects were rotated from high-density to low-density conditions for varying lengths of time. Results of short-term increases in spatial density (crowding) supported the conflict-avoidance strategy for females, through reduced levels of aggressive (F_1,16 = 17.11, p = 0.001) and affiliative (F_1,16 = 21.13, p < 0.001) behaviors. Males, however, supported the tension-reduction model during short-term high-density by decreasing aggression (F_1,5 = 10.53, p = 0.02) while increasing affiliation (F_1,5 = 9.10, p = 0.03). Females partially supported the tension-reduction model during long-term high-density by increasing affiliative behaviors (F_1,16 = 14.19, p = 0.002) compared to short-term high-density levels, while rates of aggression remained low. Finally, males supported the tension-reduction by reducing aggression (F_1,5 = 7.668, p = 0.04) and increasing affiliation (F_1,5 = 6.08, p = 0.05) during long-term high-density. Results confirm that chimpanzees use different strategies during short-term versus long-term increases in spatial density and that these strategies may be influenced by individual sex. However, sample sizes are small and additional research on male chimpanzees is needed.     

Effects of developmental exposure to bisphenol A on spatial navigational learning and memory in rats: A CLARITY-BPA study

Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of a wide variety of items. Previous studies suggest BPA exposure may result in neuro-disruptive effects; however, data are inconsistent across animal and human studies. As part of the Consortium Linking Academic and Regulatory Insights on BPA Toxicity (CLARITY-BPA), we sought to determine whether female and male rats developmentally exposed to BPA demonstrated later spatial navigational learning and memory deficits. Pregnant NCTR Sprague–Dawley rats were orally dosed from gestational day 6 to parturition, and offspring were directly orally dosed until weaning (postnatal day 21). Treatment groups included a vehicle control, three BPA doses (2.5 μg/kg body weight (bw)/day—[2.5], 25 μg/kg bw/day—[25], and 2500 μg/kg bw/day—[2500]) and a 0.5 μg/kg/day ethinyl estradiol (EE)-reference estrogen dose. At adulthood, 1/sex/litter was tested for seven days in the Barnes maze. The 2500 BPA group sniffed more incorrect holes on day 7 than those in the control, 2.5 BPA, and EE groups. The 2500 BPA females were less likely than control females to locate the escape box in the allotted time (p value = 0.04). Although 2.5 BPA females exhibited a prolonged latency, the effect did not reach significance (p value = 0.06), whereas 2.5 BPA males showed improved latency compared to control males (p value = 0.04), although the significance of this result is uncertain. No differences in serum testosterone concentration were detected in any male or female treatment groups. Current findings suggest developmental exposure of rats to BPA may disrupt aspects of spatial navigational learning and memory.     

Salivary vasopressin increases following intranasal oxytocin administration

Extant research has documented the effects of intranasal administration of oxytocin (OT), and to a lesser degree Arginine Vasopressin (AVP) – two structurally-related neuropeptides – on brain and behaviour, yet the effects of exogenous manipulation of one on circulating levels of the other remain unknown. Studies have shown that OT administration impacts the peripheral levels of numerous hormones; however, whether OT administration also increases AVP concentrations has not been explored. Utilizing a double-blind placebo-controlled within-subject design, ten male and female subjects provided ten saliva samples over four consecutive hours: at baseline and nine times following OT administration. Results indicate that salivary AVP increased in the first hour following OT manipulation (OT condition: mean AVP = 2.17 pg/ml, SE = 28, placebo condition: mean AVP = 1.42 pg/ml, SE = .18) but returned to baseline levels at the next assessment (80 min) and remained low for the remaining period. Similar to OT, AVP showed high degree of individual stability and baseline levels of AVP correlated with AVP concentrations at the first and second post-administration hours regardless of drug condition (Pearson r = .85–.93). Validity of salivary AVP ELISA measurement was verified by demonstrating individual stability of salivary AVP over a six-month period (r = .70, p < .000) as well correlation with plasma levels over the same period (r = .32, p = .037) in a sample of 45 young adults who did not participate in the current study. Overall, findings suggest a potential crosstalk between OT and AVP and indicate that baseline levels of the two neuropeptides may shape the degree to which these systems respond to exogenous manipulation.     

Placental antiangiogenic prolactin fragments are increased in human and rat maternal diabetes

Introduction/objectivesThe role of the placenta in diabetic mothers on fetal development and programming is unknown. Prolactin (PRL) produced by decidual endometrial cells may have an impact. Although full-length PRL is angiogenic, the processed form by bone morphogenetic protein-1 (BMP-1) and/or cathepsin D (CTSD) is antiangiogenic.The objectives were to investigate the involvement of decidual PRL and its antiangiogenic fragments in placentas from type-1 diabetic women (T1D) and from pregnant diabetic rats with lower offspring weights than controls.MethodsPRL, BMP-1, and CTSD gene expressions and PRL protein level were assessed in T1D placentas (n = 8) at delivery and compared to controls (n = 5). Wistar rats received, at day 7 of pregnancy, streptozotocin (STZ) (n = 5) or nicotinamide (NCT) plus STZ (n = 9) or vehicle (n = 9). Placental whole-genome gene expression and PRL western blots were performed at birth.ResultsIn human placentas, PRL (p < 0.05) and BMP-1 (p < 0.01) gene expressions were increased with a higher amount of cleaved PRL (p < 0.05) in T1D than controls. In rats, diabetes was more pronounced in STZ than in NCT–STZ group with intra-uterine growth restriction. Decidual prolactin-related protein (Dprp) (p < 0.01) and Bmp-1 (p < 0.001) genes were up-regulated in both diabetic groups, with an increased cleaved PRL amount in the STZ (p < 0.05) and NCT–STZ (p < 0.05) groups compared to controls. No difference in CTSD gene expression was observed in rats or women.ConclusionsAlterations in the levels of the PRL family are associated with maternal diabetes in both rats and T1D women suggesting that placental changes in these hormones impact on fetal development.     

Exogenous testosterone decreases men's personal distance in a social threat context

BackgroundTestosterone can motivate human approach and avoidance behavior. Specifically, the conscious recognition of and implicit reaction to angry facial expressions is influenced by testosterone. The study tested whether exogenous testosterone modulates the personal distance (PD) humans prefer in a social threat context.Methods82 healthy male participants underwent either transdermal testosterone (testosterone group) or placebo application (placebo group). Each participant performed a computerized stop-distance task before (T1) and 3.5 h after (T2) treatment, during which they indicated how closely they would approach a human, animal or virtual character with varying emotional expression.ResultsMen's PD towards humans and animals varied as a function of their emotional expression. In the testosterone group, a pre-post comparison indicated that the administration of 50 mg testosterone was associated with a small but significant reduction of men's PD towards aggressive individuals. Men in the placebo group did not change the initially chosen PD after placebo application independent of the condition. However comparing the testosterone and placebo group after testosterone administration did not reveal significant differences. While the behavioral effect was small and only observed as within-group effect it was repeatedly and selectively shown for men's PD choices towards an angry woman, angry man and angry dog in the testosterone group. In line with the literature, our findings in young men support the influential role of exogenous testosterone on male's approach behavior during social confrontations.     

Impact of social stress during gestation and environmental enrichment during lactation on the maternal behavior of sows

The impact of a social stress in gestation and an enriched pen in lactation on components of sow maternal behavior was studied in a 2 × 2 factorial experiment. At breeding, 41 sows were assigned to a social mixing stress treatment (T) during mid-gestation or a control group (C). During lactation, half of the T and C sows were housed in straw enriched pens (E) (1.57 m × 4.10 m) and the others in standard farrowing crates (S) (0.68 m × 2.10 m). The mixing stress consisted in introducing each T sow to the home pen of two unfamiliar sows twice for 1 week, from d 39 to 45 and 59 to 65 of gestation. Aggressive behavior was observed and lesion scores were taken to confirm that a social stress occurred. During lactation, the responses of sows to a simulated piglet crush test on d 3 and an isolated piglet playback test on d 21 were observed. Postural budgets of sows were automatically detected using accelerometers on d 5 and 19 of lactation. Sow-initiated social contacts with the piglets were observed continuously from video recordings on d 6 and 20 of lactation. Data were analyzed with a mixed models procedure. The social stress treatment had an impact on the response of sows to isolated piglet vocalizations with T sows showing longer latencies to respond vocally than C sows (P = 0.035). In early lactation, T sows spent more time lying ventrally than C sows (P = 0.007). Furthermore, the social stress had an impact on the space use in the enriched housing, with T sows spending less time in the nesting straw area of the pen than C sows (P = 0.018). Housing also impacted maternal behavior with E sows tending to spend more time lying ventrally than S sows in late lactation (P = 0.067) and tending to have more social contacts with their piglets than S sows in early lactation (P = 0.058). In conclusion, the social stress during gestation had a slight negative impact on sow maternal behavior, and while an enriched farrowing pen allowed for more opportunities to express maternal behavior, it did not counteract the negative effects of gestation stress.     

Mixing at the beginning of fattening moderates social buffering in beef bulls

Cattle establish strong preferential associations early in their life that determine the cohesiveness within a group and can diminish fear responses (i.e. social buffering). Mixing beef bulls at the beginning of fattening may lead to less cohesiveness. Moreover, mixing beef bulls induces aggressive interactions, especially when the bulls are of similar weights. This study was aimed at evaluating the cohesiveness and fear responses of 64 bulls that were either mixed versus unmixed and of homogeneous vs. heterogeneous body weights (2 × 2 factorial design, four groups of four bulls each per treatment). Social cohesiveness was assessed during food competition and a social separation test. Fear responses were observed during the social separation test and pre-slaughter handling. During food competition, unmixed bulls exchanged more non-agonistic interactions (P < 0.05) and were more tolerant with each other than mixed bulls (time spent eating: P < 0.05). Unmixed bulls displayed less fear responses during physical separation (elimination: P < 0.05; startle: P < 0.01) and were less stressed by pre-slaughter handling (blood cortisol: P < 0.05). Very few effects could be attributed to the homogeneity of weights within groups. It is concluded that mixing bulls at the beginning of fattening reduces the strength of positive social relationships and renders social buffering less effective during subsequent fattening. We recommend maintaining familiar bulls together throughout fattening in order to preserve cohesiveness within groups and for animals to benefit from social buffering during stressful situations.     

Carnosine ameliorates cognitive deficits in streptozotocin-induced diabetic rats: Possible involved mechanisms

Diabetic patients are at increased risk to develop cognitive deficit and senile dementia. This study was planned to assess the benefits of chronic carnosine administration on prevention of learning and memory deterioration in streptozotocin (STZ)-diabetic rats and to explore some of the involved mechanisms. Rats were divided into 5 groups: i.e., control, carnosine100-treated control, diabetic, and carnosine-treated diabetics (50 and 100 mg/kg). Carnosine was injected i.p. at doses of 50 or 100 mg/kg for 7 weeks, started 1 week after induction of diabetes using streptozotocin. Treatment of diabetic rats with carnosine at a dose of 100 mg/kg at the end of the study lowered serum glucose, improved spatial recognition memory in Y maze, improved retention and recall in elevated plus maze, and prevented reduction of step-through latency in passive avoidance task. Furthermore, carnosine at a dose of 100 mg/kg reduced hippocampal acetylcholinesterase (AChE) activity, lowered lipid peroxidation, and improved superoxide dismutase (SOD) activity and non-enzymatic antioxidant defense element glutathione (GSH), but not activity of catalase. Meanwhile, hippocampal level of nuclear factor-kappaB (NF-κB), tumor necrosis factor α (TNF-α), and glial fibrillary acidic protein (GFAP) decreased and level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) increased upon treatment of diabetic group with carnosine at a dose of 100 mg/kg. Taken together, chronic carnosine treatment could ameliorate learning and memory disturbances in STZ-diabetic rats through intonation of NF-κB/Nrf2/HO-1 signaling cascade, attenuation of astrogliosis, possible improvement of cholinergic function, and amelioration of oxidative stress and neuroinflammation.     

Dietary preference for methionine sources in weaned pigs

The objective of the current study was to investigate the preference of weaned pigs given the choice of diets supplemented with dl-methionine (DLM) or liquid dl-methionine hydroxy analog-free acid (MHA-FA). A basal diet (BD) was formulated to contain 2.5 g methionine (Met) per kilogram of diet. The experimental diets included: (1) BD, (2) BD + 1 g DLM/kg, (3) BD + 2 g DLM/kg, (4) BD + 1.13 g MHA-FA/kg, (5) BD + 1.52 g MHA-FA/kg, (6) BD + 2.25 g MHA-FA/kg and (7) BD + 3.05 g MHA-FA/kg. Sixty weaned mixed-sex pigs were allotted to 5 treatment groups with 12 pig replicates per treatment in a randomized complete block design. During a 35-day experimental period, pigs in treatment group 1 received the BD whereas pigs in the other 4 treatment groups were allowed to choose between a pair of diets with either added 1 g DLM/kg in combination with either 1.13 or 1.52 g MHA-FA/kg or 2 g DLM/kg in combination with 2.25 or 3.05 g MHA-FA/kg, respectively. Pigs were housed in individual pens and had free access to feed and water. Daily feed intake (FI) was used as an indicator of diet preference. Cumulatively, pigs showed a preference (% of total FI) for the diet added with 1 g/kg DLM at 74% (P<0.05) in group 2, and 65% in group 3. Irrespective of the level of MHA-FA supplementation (2.25 or 3.05 g/kg), a preference for the diet supplemented with 2 g DLM/kg was 84% (P<0.05) in groups 4 and 5. During the entire period, pigs consistently (P<0.05) consumed more and preferred the diets supplemented with DLM more than the diets supplemented with MHA-FA in groups 2, 4 and 5. The preference for diets supplemented with DLM was more pronounced at higher Met supplementation levels. Feeding pigs a pair of diets supplemented with DLM or MHA-FA improved (P<0.05) the final body weight, daily weight gain, and FCR. The performance of pigs among the Met-supplemented groups was not different. In conclusion, when given a choice pigs preferred the diets supplemented with DLM more than the diets supplemented with liquid MHA-FA.     

The phytoestrogen ferutinin improves sexual behavior in ovariectomized rats

The present study was designed to examine the effect of ferutinin chronic administration on sexual behavior of ovariectomized non-estrogen-primed rats. Starting from 3 weeks after ovariectomy, female rats were orally treated with ferutinin at the doses of 0.2 and 0.5 mg/kg, daily for 4 weeks. Ferutinin's effect was compared with that of estradiol benzoate, subcutaneously injected at the dose of 1.5 μg/rat twice a week. Animals were tested for sexual motivation, receptivity and proceptivity after 1, 2 and 3 weeks of treatment and for paced mating behavior after 4 weeks of treatment. Before each experimental test, they received progesterone injection (500 μg/rat).Both dosages of ferutinin significantly increased the receptive behavior in a time-dependent manner, as well as estradiol benzoate did. Also proceptive behaviors increased in ferutinin-treated animals in comparison with control ones. During the partner preference test ferutinin was able to induce a significant preference for a sexually active male over a sexually receptive female. Moreover, ferutinin restored a normal paced mating behavior, which had been suppressed by ovariectomy. These results show that ferutinin exerts an estrogenic activity in ovariectomized non-estrogen-primed female rats.