Efficacy of alphas1-casein hydrolysate on stress-related symptoms in women.

OBJECTIVE: To examine the effects of alpha (s1)-casein hydrolysate on females with stress-related symptoms. DESIGN: Double-blind, randomized, crossover, placebo-controlled trial. SETTING: The alpha (s1)-casein hydrolysate was manufactured by INGREDIA (Arras, France) and the placebo was manufactured by DIETAROMA (Bourg, France). Study was designed and performed at PROCLAIM (Rennes, France), and the statistical analyses were performed by D Desor (Nancy, France). SUBJECTS: A total of 63 female volunteers suffering from at least one disorder that may be related to stress such as anxiety, sleep problems and general fatigue. INTERVENTIONS: A total of 63 volunteers participated in a double-blind, randomized, crossover, placebo-controlled study. Subjects were randomly allocated to receive either tablets containing alpha (s1)-casein hydrolysate or placebo at the dose of 150 mg/day for 30 days. After a 3 weeks washout period, they were crossed over for a new 30-day period of tablets intake. The outcome measure was a questionnaire including 44 items of symptoms that may be related stress in which the severity of each sign was evaluated using a 10-degree scale. These measures were studied repeatedly at the day of 0, 15 and 30 after the start of each interventional period. RESULTS: The 30-day treatment by alpha (s1)-casein hydrolysate in females with stress-related symptoms reduced their symptoms, particularly in digestion (P<0.01), cardiovascular (P<0.05), intellectual (P<0.01), emotional (P<0.05) and social problems (P<0.05). CONCLUSION: This study showed that a 30-day ingestion of alpha (s1)-casein hydrolysate decreased the stress-related symptoms in females suggesting that this product may be used as an effective functional ingredient alleviating such symptoms. SPONSORSHIP: This study was partially supported by the INGREDIA of France and Neurobiology Research Program from the Korea Ministry of Science and Technology (2004-01757) of Korea.

Long-term effects of early diazepam exposure on social differentiation in adult male rats subjected to the diving-for-food situation.

The present study was designed to investigate the consequences of a chronic diazepam (DZ) exposure (10 mg/kg/day) during the first 3 weeks of life on social behavior of adult male rats measured in a situation of restricted access to food, the diving-for-food model. The treatment had no long-term effects on the acquisition of social roles related to feeding. However, DZ-exposed rats were less efficient than controls in carrying food from the feeder to the cage during the 1st session but were able to adapt and improve their performances during the 2nd one. In the home cage, DZ-exposed rats were more aggressive toward conspecifics than controls and compensated for their deficit of food by stealing it from the others. These results suggest that an early DZ exposure has long-term consequences on social behavior of rats, possibly reflecting a reduction of the level of emotionality.

Behavioral evaluation of visceral pain in a rat model of colonic inflammation.

A new rat model was established up to evaluate the antinociceptive effect of compounds in visceral pain. The test consisted in measuring the performance of rats in an aversive light stimulus avoidance experimental device. Rats with TNBS-induced colitis had a lower number of total active lever pressings and did not discriminate the active lever from the inactive one. Morphine (1 mg/kg, s.c.) and CI-977 (0.001 mg/kg, s.c.) treatment restored the level of pressing activity of animals and their ability to discriminate the active lever from the inactive one. Naloxone treatment antagonized the improvement of performance produced by morphine. The results obtained indicate that this behavioral paradigm may be used to evaluate the antinociceptive potential of compounds.

Long-term consequences of neonatal exposure to diazepam on cerebral glucose utilization, learning, memory and anxiety.

The long-term consequences of neonatal exposure to diazepam (DZP) on behavioral abilities and local cerebral glucose utilization (LCGU) in 12 brain regions involved in the control of memory and anxiety were studied in adult rats. Rat pups received a daily subcutaneous injection of 10 mg/kg DZP or of the dissolution vehicle from postnatal day (P) 2 to 21. Learning and memory were tested in P60-P70 rats over 5 consecutive days in a T maze and an eight-arm maze while anxiety and reaction to novelty were tested in a two-compartment box with a two-step staircase on the enriched side. LCGU was measured in the P60 rat by the quantitative autoradiographic [14C]deoxyglucose method. In the T maze, when performed without delay between the two trials, the rate of alternation was significantly lower in DZP- than in vehicle-exposed rats on the first 2 days of testing and similar in both groups on days 3-5. In the procedure with a 30 s intertrial delay, the rate of alternation was similar in DZP- and vehicle-treated rats on all days of testing. In the eight-arm maze, DZP-treated rats were more active, i.e., entered more arms per minute than control animals. The number of arms entered before the first error was lower on day 1 and higher on day 3 in DZP- compared to vehicle-exposed rats. In the two-compartment box, DZP-treated rats crossed more often and spent more time than controls on the lower step of the staircase while control rats made more rearings and spent more time than DZP-exposed rats in the well protected corner of the box. LCGU were decreased by early DZP exposure in six regions which were mammillary body, septum, visual and prefrontal cortices, dorsomedian caudate nucleus and mediodorsal thalamus. In conclusion, postnatal DZP treatment induced at adulthood an increase in activity, a delay in task acquisition but no learning-memory impairment and reduced the level of anxiety allowing active responding to novelty. These quite subtle behavioral changes were accompanied by discrete metabolic decreases in regions mediating anxiety, reflecting a change in the level of anxiety and emotionality.

Effect of group size on social organization in rats with restricted access to food.

In groups of rats subjected to a experimental design in which access to the feeder was made difficult, a behavioural differentiation developed. Some rats brought back food pellets to the cage (carrier rats) while the others stayed in the home cage (noncarrier rats). We compared the social organization underlying the adoption of these roles in groups of three and six rats. Reducing group size increased the incidence of carrier rats, leading to a smaller number of differentiated groups. However, differentiated groups seemed to adapt to the situation in the same way as the groups of six rats. In both cases, carriers could be distinguished from noncarriers by their way of obtaining food and by how food possession stopped. Moreover, behavioural variables generally exhibited better stability in small groups and noncarrier/carrier rat relations were more extensive, resulting in more typical organization. The potential use of such groups for pharmacological studies is discussed.

Ingestive behaviors of the rat deficient in vasopressin synthesis (Brattleboro strain). Effect of chronic treatment by dDAVP.

Spontaneous manipulator and locomotor activities, food and fluid intake have been recorded from rats suffering from a genetic lack of central vasopressin (VP) synthesis (Brattleboro strain, DI), their heterozygous litter mates (HZ) or Long Evans (LE) rats. The daily patterns of activities did not differ, except for their drinking behavior. This was mainly associated with food intake during the dark period with LE rats but was distributed equally during light and dark periods with DI rats. HZ rats showed a behavioral heterogeneity, some of them following the daily pattern of LE rats, and others, that of DI rats. The daily feeding pattern was identical in the three genotypes but the selection between two isocaloric contrasted diets was different. When they were fed ad lib, HZ and DI rats consumed less carbohydrate than LE rats, the protein intake being unchanged. On the contrary, when the DI rats were only fed during the dark period, they ate more carbohydrate than LE rats. The peripheral infusion of a V2 AVP agonist (dDAVP) restored a normal hydric balance in DI rats but failed to modify the diet selection. These data show that in the rats, the lack of central VP synthesis disturbs both the selection of diets and the efficiency of the satiety signals. These disturbances were unchanged by the peripheral VP treatment which suggested the direct involvement of the central release of the neuropeptide.

Effects of postnatal aluminum exposure on biological parameters in the rat plasma.

Young rats were treated by gastric intubation with aluminum chloride (100 mg Al/kg/day) and aluminum lactate (100 and 200 mg Al/kg/day) from postnatal days 5 to 14. This treatment lead to a reduction in body weight. The plasma concentrations of total proteins and albumin decreased whereas the alpha 1 globulins increased in the treated rats. The aluminum concentrations in plasma and hepatic homogenates increased particularly at 200 mg Al lactate. The reduction in average body weight could be attributed to various causes: a decreased food consumption, a transient undernutrition, a reduction of the protein synthesis in the liver. The increase of the plasma concentration of the alpha 1 globulins revealed an inflammation process.

Effects of postnatal aluminum exposure on choline acetyltransferase activity and learning abilities in the rat.

Young rats were treated by gastric intubation with aluminum lactate (0, 100, and 200 mg Al/kg/day) from postnatal days 5 to 14 to determine the treatment's influence on brain choline acetyltransferase activity and learning abilities. The results indicated that aluminum concentrations in the cerebral areas increased in parallel to plasma aluminum at the dose of 200 mg. In the same case, choline acetyltransferase activity was reduced. At postnatal days 50 and 100, the treated rats did not show alterations in their learning abilities in the 2 tests which are based on different motivations (avoidance of an aversive light or alimentary motivation) and different ways of achievement (pressing on a lever or running in a maze). A low reduction in the general activity, particularly in the radial maze test, was only observed in rats treated with 200 mg Al/kg/day.

Effects of fluoxetine and norfluoxetine on 5-hydroxytryptamine metabolism in blood platelets and brain after administration to rats.

The effects of intraperitoneal administration of fluoxetine (2.5, 5, 10 or 20 mg kg(-1)) and norfluoxetine (10 mg kg(-1)) on 5-hydroxytryptamine (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) metabolism were examined in the blood platelets and brain of rats killed 3 h after a single dose. Several experiments were performed to evaluate the effect of norfluoxetine. Plasma 5-HT concentrations decreased significantly (48%) compared with control group results 3 h after administration of a single dose of fluoxetine (10 or 20 mg kg(-1)). Similar plasma 5-HT levels, 0.54+/-0.04 and 0.56+/-0.09 mg L(-1), respectively, were observed after administration of 10 mg kg(-1) fluoxetine or norfluoxetine. In the same way 5-HIAA levels in whole brain were similar, 0.36+/-0.03 and 0.34+/-0.01 microg(-1), respectively, after administration of fluoxetine or norfluoxetine. There was a good correlation between plasma and brain levels of fluoxetine (0.962) and norfluoxetine (0.957). The results suggest that fluoxetine and norfluoxetine lead to reduced levels of 5-HT in platelets and of 5-HIAA in the brain. Like the parent drug, norfluoxetine is a potent and selective inhibitor of 5-HT uptake.

Behavioral differentiation of mice exposed to a water tank social interaction test.

Male or female C57BL/6J mice were exposed to a water tank in which food could be obtained only by wading in the water towards a feeder. Behavioral differentiation occurred in that three distinct categories could be distinguished: major carriers (transporting over 80% of the food pellets), sporadic carriers (transporting less than 20% of the food pellets) and non-carriers. In the elevated + -maze, major carriers were more willing to explore open spaces than non-carriers. Sporadic carriers showed some evidence of the same tendency of decreased anxiety, but in a minor way. The willingness of mice to become carriers is associated with their willingness to explore novel areas. This test may be useful for the assessment of anxiolytic compounds in a social situation.

Effects of aluminum chloride on normal and uremic adult male rats. Tissue distribution, brain choline acetyltransferase activity, and some biological variables.

Normal and uremic adult male rats were given a daily ip injection of 20 mg Al (Al chloride)/kg for 14 d. The results indicate that Al induces a significant decrease in food ingestion, weight gain, and total protein concentration in the plasma. Compared with control animals, very high increases in Al levels were found in plasma and hepatic homogenates (about 36 and 19 times, respectively). In the brain homogenates, the Al increases were lower (about 23%). The brain cholineacetyltransferase activity was reduced: 10.6 and 14.9% in normal and uremic rats, respectively. The nephrectomy and the food restriction did not affect the total protein concentrations in plasma and the cerebral cholineacetyltransferase activity. Both were only found to be reduced in the rats treated by Al chloride.

Effect of aluminum on superoxide dismutase activity in the adult rat brain.

Male rats were treated daily with an intraperitoneal injection of 15 mg aluminum (Al chloride)/kg body weight for 17 d, in order to study the effects on superoxide dismutase (SOD) activities in the brain (cortex). No significant difference between control and treated animals was registered in the Cu/Zn and Mn SOD activities in the gray matter of the cortex. High Al levels were found in the plasma, the spleen, and the liver of the treated animals in comparison to the controls, but not in the cortex homogenates (gray matter). In addition, Al induced a significant decrease in food ingestion and weight gain.

[Chronic prenatal exposure to diazepam, brain metabolism and behavior: long-term consequences in the adult rat]. / Exposition chronique précoce au diazépam, métabolisme cérébral et comportement: conséquences à long terme chez le rat adulte.

The long-term consequences of a neonatal exposure to diazepam (DZP) on behavioral abilities and local cerebral metabolic rates for glucose (LCMRglc) in selected brain regions involved in the control of memory and anxiety were studied in adult rats. Rat pups received a daily subcutaneous injection of 10 mg/kg DZP or of the dissolution vehicle from postnatal day (P) 2 to 21. Learning and memory were tested in P60-P70 rats on 5 consecutive days in a T maze and an eight arm maze while anxiety and reaction to novelty were tested in a 2 compartment box with a 2 step staircase on one side. Social behavior was evaluated in a condition of restricted access to food. LCMRglcs were measured at P60 by the quantitative autoradiographic [14C]deoxyglucose method. In the T maze, when performed without delay between the 2 trials, the rate of alternation was significantly lower in DZP than in vehicle-exposed rats on the first 2 days of testing and similar in both groups on days 3-5. In the procedure with a 30 s intertrial delay, the rate of alternation was similar in DZP and vehicle-treated rats on all days of testing. In the eight arm maze, DZP-treated rats were more active, i.e. entering more arms per min than control animals. The number of arms entered before the first error was lower on day 1 and higher on day 3 in DZP compared to vehicle-exposed rats. In the 2 compartment box, DZP-treated rats crossed more often the lower step of the staircase and spent more time than controls on the 2 steps of the staircase while control rats made more rearings than DZP-exposed rats in the well protected corner of the box. LCMRglcs were decreased by early DZP exposure in several cortical regions, mammillary body, septum and dorsomedian caudate nucleus. In conclusion, an early chronic DZP treatment induces an increase in activity, only a delay but no impairment in learning and leads to a decrease in the level of anxiety and emotionality leading to an active response to novelty. These quite subtle behavioral changes are accompanied by discrete metabolic changes and probably reflect the state of hyperactivity/hyperarousal of these animals which could result from a change in the distribution, the sensitivity and/or function of GABA-BZD receptors.

[Fluoxetine: relations between plasma concentration and therapeutic effects in 32 patients with major depression and treated with 20 mg/day]. / Fluoxétine: relations entre concentrations plasmatiques et effets thérapeutiques chez 32 patients atteints de dépression majeure et traités à 20 mg/j.

The aim of this clinical study was to investigate 32 melancholic patients treated by fluoxetine (20 mg/day). The clinical examination to evaluate the antidepressant effect of fluoxetine was realized by using the HDS/MES criteria. The patients were divided into three groups (responders, partial responders with or without a relapse, non responders) according to their clinical evolution during treatment. Fluoxetine and norfluoxetine were evaluated by HPLC after 3 weeks of treatment. In the present study, 53% of the patients have a positively reaction to the 21 day's treatment. Our results showed no correlation between the psychiatric scores and the plasma concentrations of fluoxetine and norfluoxetine.

[Effect of fluoxetine treatment on serotonin and MHPG in 32 patients with major depressive disorder]. / Effet d'un traitement à la fluoxétine sur la sérotonine et le MHPG chez 32 patients atteints de dépression majeure.

Considering the concept that depressive disorders were not only resulting from activity of one neurotransmitter, possible interactions between the noradrenergic system and a selective serotonin uptake inhibitor, fluoxetine, were investigated in order to test the hypothesis of noradrenergic or serotonergic involvement in depression. So the biological parameters (plasma and urinary MHPG, platelet serotonin) were evaluated by HPLC. The aim of this study was to evaluate the correlations between the concentrations of MHPG and serotonin in 32 melancholic patients treated by fluoxetine (20 mg/day) during a minimum of three weeks. The clinical examination with evaluation of the antidepressant effect carried out using the HDS/MES rating scale, allowed to divide the patients into three groups: responders to treatment, partial responders and non responders. In the same time, a control group of healthy subjects was investigated. ANOVA applied to platelet serotonin at day 0 showed a tendency toward heterogeneity between the three patient groups and the control group. The concentrations of serotonin in the three patients groups were highly reduced after 21 days of treatment. Concerning plasma and urinary MHPG there was non significant difference among the three patients groups at day 0 and the control groups. After treatment by fluoxetine, the results suggest that the urinary sulfate MHPG is an indicator of the metabolism of brain norepinephrine and seems to be a better turnover indicator than the plasma sulfate MHPG. The selective evaluation of sulfate and glucuronide MHPG could give a better survey of the psychobiological state of the patients than the total MHPG evaluation.

Behavioural differentiation of rats confronted to a complex diving-for-food situation.

Previous studies have shown that a behavioural differentiation appeared in groups of rats subjected to an experimental design in which access to the feeder was made difficult. Some rats brought back food pellets to the cage (divers) while the others (non-divers) stayed in the sole home cage and obtained food only by stealing it from divers. In this study, we elaborated a more complex diving-for-food device which allowed divers to consume the food in a second cage away from non-divers. As a result, the expected lack of suppliers should not allow the emergence of the non-diver status. Unexpectedly, our results showed the apparition of non-divers and the persistence of divers (divers c1) bringing food back to the initial cage. Two new categories of rats appear: individuals which consume the food in the second cage where they stay once they have reached it (divers c2), or occasionally go back to the initial cage throughout the experiment (divers c1c2). Our results show the influence of spatial environment on social organization of rats and suggest that social pressure strongly determines the emergence of specialized roles in a group.

Selective pup retrieving by mother rats: sex and early development characteristics as discrimination factors.

Discrimination between own-litter pups by mother rats was studied over 14 litters, in a standardized situation eliciting maternal pup-retrieving activity. Results showed some consistency in the order in which pups of a litter were retrieved by the mother in the 4-day and 9-day tests and that this order was related to certain characteristics of the pups: 1) on Day 4 and 9, the best-developed pups of the litter (in terms of body weight and neuromotor behaviors) were first retrieved; 2) on Day 9, sex of pups became an additional discrimination factor, as males were retrieved before their female littermates. Variables included in these global discrimination factors and possible consequences of such differential mother-pups interactions are discussed.

Influence of environment structure and food availability on the foraging behaviour of the laboratory rat.

According to the optimal foraging theory, an animal is expected to enter into a given activity depending on associated costs and benefits. In line with this assumption, numerous studies have suggested that energetic reward is balanced by predation risk in foraging decisions. Therefore, the use of information about indirect cues of predation risk such as physical structure (e.g. cover, escape substrate) can give individuals a selective advantage. We studied foraging behaviour in the laboratory rat in an experimental maze; it allowed us to vary two environmental parameters: food availability and physical structure. In a first experiment, rats were offered a choice between two areas only differing in cover density. In a second experiment, the two areas only differed in food density. In a third experiment, we crossed both parameters. Our results showed that high "cover" patch was preferentially exploited (experiment 1) and that rats foraged more in the high food density patch (experiment 2). The last experiment showed that rats partially trade-off between cover density and food availability, even if the safest area was still preferred. Therefore, we suggest that foraging decisions depend primarily on safety needs, rather than food availability, at least when animals are not severely food-deprived.

Maternal behavior variations and adaptations, and pup development within litters of various sizes in Wistar rat.

Variations of two maternal behavior components (time spent with litter and rapidity of pup retrieving) as well as certain physical and developmental characteristics of pups (weight, relative weight gain, and neuromotor maturation) in rats were simultaneously studied in 29 various-sized litters in which interindividual variations were not experimentally amplified. Results showed mothers' behavioral adaptations to litters' characteristics (size and weight). Time spent with young was linked to litter size, whereas rapidity of pup retrieving was related to the pups' physical characteristic. Beyond these adaptive variabilities, residual variations subsisted between mothers. These variations were determinant for differences in pup development for only one component: the time that mothers spent with their litters, while pup retrieving component variations did not have any effect.

The endogenous androgen-regulated sialorphin modulates male rat sexual behavior.

In sexually mature male rats, sialorphin is synthesized under androgenic control and its surge endocrine secretion is evoked in response to environmental acute stress. These findings led us to suggest that this signaling mediator might play a role in physiological and behavioral integration, especially reproduction. The present study investigates the effects induced by sialorphin on the male sexual behavior pattern. Intact male rats were treated in acute mode, with sialorphin at the 0.3, 1, and 3 microg/kg doses, before being paired with receptive female for 45 min. The data obtained show that sialorphin increased, in a dose-related manner, the occurrence of intromissions across the successive ejaculatory sequences. The rats treated with the highest 3 microg/kg dose significantly ejaculated less often compared to controls; however, 80% of them achieved up to three ejaculations. Further analyses of mount bouts for rats achieving three ejaculations reveal that there were significant stimulatory effects of sialorphin, at all doses, on the frequency of intromissions before ejaculation and on the propensity of males to engage in investigatory behavior directed to the female during the post-ejaculatory interval. Thus, sialorphin has the ability to modulate, at doses related to physiological circulating levels, the male rat mating pattern, that is, exerting a dual facilitative or inhibitory dose-dependent effect on the sexual performance, while stimulating the apparent sexual arousal or motivation. These findings led us to speculate that the endogenous androgen-regulated sialorphin helps modulate the adaptative balance between excitatory and inhibitory mechanisms serving appropriate male rat sexual response, depending on the context.