Biomedical subjects

B M Spruijt

Publications and source records attributed to B M Spruijt.

At least 19 recordsLinked to original sources

PubMed2006

Slaughter of poultry during the epidemic of avian influenza in the Netherlands in 2003.

During an outbreak of avian influenza in the Netherlands in spring 2003, the disease was controlled by destroying all the poultry on the infected farms and on all the farms within a radius of 3 km. In total, 30 million birds were killed on 1242 farms and in more than 8000 hobby flocks, by using mobile containers filled with carbon dioxide, mobile electrocution lines and by gassing whole poultry houses with carbon monoxide or carbon dioxide. Observations of these methods were used to compare their effectiveness and capacity, and their effects on the welfare of the birds. Gassing whole poultry houses had a much greater capacity than mobile equipment, and catching live birds to bring them to a mobile killing device caused extra stress and could cause pain due to injuries inflicted when catching and handling them. Gassing whole poultry houses with carbon monoxide requires strict safety regulations and, therefore, gassing with carbon dioxide was considered preferable. However, this method is not suited to all types of housing, and in these circumstances mobile killing devices were a useful alternative.

Animal Husbandry↗

PubMed2006

Susceptibility of duck and turkey to severe hypercapnic hypoxia.

Large groups of poultry, including ducks and turkeys, are killed for disease control purposes with CO2. In this study, we examined the physiological reaction of White Pekin ducks and turkeys to increasing CO2 concentrations. Additionally, we examined the suitability of killing both species with increasing CO2 concentrations. Blood gas values showed similar reaction patterns for both species: a strong increase in pCO2 from approximately 40 to 200 mmHg, decreasing pO2 and O2 saturation, a decrease in pH from 7.4 to 6.7, and a strong shift in acid-base equilibrium (averaging 0 to -23). On the electroencephalogram, theta and sigma waves occurred at 21 to 23% CO2, and suppression to a near isoelectric electroencephalogram occurred between 41.8 and 43.4% CO2 in inhaled air. Heartbeat declined from approximately 300 beats per min (bpm) at the start to 225 bpm at loss of posture to 150 bpm at 1 min before the heartbeat ceased. During the last phase of heart activity, an irregular rhythm and fibrillation were observed in addition to a decline in bpm. Blood gas values and electrophysiological data confirmed that ducks and turkeys lose consciousness before a level of 25% CO2 in inhaled air is reached and that both ducks and turkeys die within 13 min in an environment of 45% CO2 in inhaled air.

Acid-Base Equilibrium↗

PubMed2006

Novel approach to the behavioural characterization of inbred mice: automated home cage observations.

Here we present a newly developed tool for continuous recordings and analysis of novelty-induced and baseline behaviour of mice in a home cage-like environment. Aim of this study was to demonstrate the strength of this method by characterizing four inbred strains of mice, C57BL/6, DBA/2, C3H and 129S2/Sv, on locomotor activity. Strains differed in circadian rhythmicity, novelty-induced activity and the time-course of specific behavioural elements. For instance, C57BL/6 and DBA/2 mice showed a much faster decrease in activity over time than C3H and 129S2/Sv mice. Principal component analysis revealed two major factors within locomotor activity, which were defined as 'level of activity' and 'velocity/stops'. These factors were able to distinguish strains. Interestingly, mice that displayed high levels of activity in the initial phase of the home cage test were also highly active during an open-field test. Velocity and the number of stops during movement correlated positively with anxiety-related behaviour in the elevated plus maze. The use of an automated home cage observation system yields temporal changes in elements of locomotor activity with an advanced level of spatial resolution. Moreover, it avoids the confounding influence of human intervention and saves time-consuming human observations.

Animals↗

PubMed2006

Effect of restraint and injection methods on heart rate and body temperature in mice.

Routine procedures in the laboratory, inducing acute stress, will have an impact on the animals and might thereby influence scientific results. In an attempt to gain more insight into quantifying this acute stress by means of the parameters heart rate (HR) and body temperature (BT), we subjected mice to different restraint and injection methods. We first compared the treatment response of HR and BT, measured by means of radiotelemetry, with the treatment response of plasma corticosterone (pCORT), a common and well-validated parameter for measuring acute stress responses. It was found that HR, and to a lesser extent also BT, parallels pCORT values after subjecting the animals to different methods of restraint. Secondly, the acute stress response caused by different injection methods was evaluated. Again, HR was found to be a more sensitive parameter than BT. We found that, in case of sham injections, the acute stress response after an intraperitoneal (i.p.) injection was more pronounced than after intramuscular (i.m.) or subcutaneous (s.c.) injections, but this difference was found to be inconsistent when saline was used as injection fluid. In a third experiment we investigated if the level of experience of the animal technician influenced the stress response after s.c. injections, but no differences were found. Overall, the results have indicated that HR might be considered as a useful parameter for measuring acute stress responses to routine procedures, but the value of BT seems to be of limited value in this respect.

Animals↗

PubMed2005

Increased gabaergic input to ventral tegmental area dopaminergic neurons associated with decreased cocaine reinforcement in mu-opioid receptor knockout mice.

There is general agreement that dopaminergic neurons projecting from the ventral tegmental area (VTA) to the nucleus accumbens and prefrontal cortex play a key role in drug reinforcement. The activity of these neurons is strongly modulated by the inhibitory and excitatory input they receive. Activation of mu-opioid receptors, located on GABAergic neurons in the VTA, causes hyperpolarization of these GABAergic neurons, thereby causing a disinhibition of VTA dopaminergic neurons. This effect of mu-opioid receptors upon GABA neurotransmission is a likely mechanism for mu-opioid receptor modulation of drug reinforcement. We studied mu-opioid receptor signaling in relation to cocaine reinforcement in wild-type and mu-opioid receptor knockout mice using a cocaine self-administration paradigm and in vitro electrophysiology. Cocaine self-administration was reduced in mu-opioid receptor knockout mice, suggesting a critical role of mu-opioid receptors in cocaine reinforcement. The frequency of spontaneous inhibitory post-synaptic currents onto dopaminergic neurons in the ventral tegmental area was increased in mu-opioid receptor knockout mice compared with wild-type controls, while the frequency of spontaneous excitatory post-synaptic currents was unaltered. The reduced cocaine self-administration and increased GABAergic input to VTA dopaminergic neurons in mu-opioid receptor knockout mice supports the notion that suppression of GABAergic input onto dopaminergic neurons in the VTA contributes to mu-opioid receptor modulation of cocaine reinforcement.

Afferent Pathways↗

PubMed2004

Reaction to frustration in high and low feather pecking lines of laying hens from commercial or semi-natural rearing conditions.

The effect of rearing conditions on feather pecking and reaction to frustration was studied in two lines of laying hens. From commercial rearing conditions (large group, no mother hen), seven birds from a high feather pecking line (HC birds) and eight birds from a low feather pecking line (LC birds) were used. From semi-natural rearing conditions (small group, mother hen present) seven birds from the high feather pecking line (HN birds) were used. Feather pecking behaviour of HC, LC, and HN groups was recorded for 30 min. After that, each bird was food deprived and trained to peck a key for a food reward in a Skinnerbox. After training, each bird was subjected to a frustration session in a Skinnerbox, where the feeder was covered with Perspex. Three HC birds showed severe feather pecking, compared with one HN bird and zero LC birds. Differences in reaction to frustration were found between birds from different lines, but not in birds from different rearing conditions. LC birds tended to put their head in the feeder more frequently than HC birds over all sessions. Although limited, this study indicates that rearing conditions influence feather pecking, but not reaction to frustration.

Animal Husbandry↗

PubMed2003

Spatial, contextual and working memory are not affected by the absence of mossy fiber long-term potentiation and depression.

The mossy fibers of the hippocampus display NMDA-receptor independent long-term plasticity. A number of studies addressed the role of mossy fiber long-term plasticity in memory, but have provided contrasting results. Here, we have exploited a genetic model, the rab3A null-mutant, which is characterized by the absence of both mossy fiber long-term potentiation and long-term depression. This mutant was backcrossed to 129S3/SvImJ and C57Bl/6J to obtain standardized genetic backgrounds. Spatial working memory, assessed in the eight-arm radial maze, was unchanged in rab3A null-mutants. Moreover, one-trial cued and contextual fear conditioning was normal. Long-term spatial memory was tested in the Morris water maze. Two different versions of this task were used, an 'easy' version and a 'difficult' one. On both versions, no differences in search time and quadrant preferences were observed. Thus, despite the elimination of mossy fiber long-term plasticity, these tests revealed no impairments in mnemonic capabilities. We conclude that spatial, contextual and working memory do not depend on mossy fiber plasticity.

Animals↗

PubMed2002

Imipramine restores the long-term impairment of appetitive behavior in socially stressed rats.

RATIONALE: Previous observations revealed that defeated and subsequently individually housed rats do not display behavioral anticipatory responses to the conditioned presentation of a bell/light stimulus associated with free access to a 5% sucrose solution reward. The absence of the appetitive responses suggests a decreased sensitivity to reward. This might be homologous to anhedonia, a symptom of human depression. OBJECTIVES: To further validate the inability to anticipate as indicative for a depressionlike state we investigated whether antidepressant treatment restores the impaired anticipatory responses in defeated and subsequently individually housed animals. METHODS: Male rats were defeated and subsequently individually housed or subjected to a control treatment. In the 19-20th weeks after the exposure to defeat rats were either injected daily with imipramine (20 mg/kg per os, dissolved in water) or water. Anticipatory behavior was measured both before and after 3-5 weeks of chronic treatment with imipramine. RESULTS: The long-term impairment of anticipatory behavior in defeated and subsequently individually housed rats was restored by chronic imipramine treatment. Impaired appetitive behavior in socially stressed rats was not accompanied by a decreased consumption of the 5% sucrose solution in the anticipatory tests. The recovery of the appetitive responses was independent of open field activity, body weight, and 5% sucrose preference in the home cage. CONCLUSIONS: Chronic imipramine administration restores the anhedonialike absence of anticipatory behavior in socially stressed rats. Predictive validity of the social stress model of human depression is suggested by the similar action of imipramine on the modeled behavior and on the anhedonia symptoms in depressive human patients.

Animals↗

PubMed2002

Individual housing during the play period results in changed responses to and consequences of a psychosocial stress situation in rats.

In the present study, the consequences of individual rearing during the play period on adult responses to aggression were investigated in a complex social setting. In a group of either socially or individually reared rats, an aggressor was repeatedly introduced. Separate control groups of individually and socially reared rats were not exposed to an aggressor. To allow an interpretation of the altered reactivity to aggression in terms of (in)efficient or (in)adequate behavior, not only the responses in the presence of the aggressor but also the consequences of the altered reactivity on subsequent behavior in the absence of the aggressor were observed. We demonstrated that a higher number of injuries, more agitation of the aggressor, and more ultrasonic distress vocalizations accompanied the altered responses of individually reared rats in the presence of the aggressor. In the absence of the aggressor, individually reared rats displayed less social stress-reducing behaviors (play and social grooming) than socially reared rats. It was concluded that individually reared rats display a less adequate response to aggression in this social context.

Aggression↗

PubMed2002

Decision support system for overall welfare assessment in pregnant sows A: model structure and weighting procedure.

The problem of how to objectively assess the overall welfare status of animals under farming conditions has contributed to an ongoing debate that has hampered actual decision making on animal welfare. For this reason we constructed a model based on the assumed hierarchical organization of the animals' needs for overall welfare assessment in the case of pregnant sows. This model is implemented in a computer-based decision support system that takes a description of a housing and management system as input and produces a welfare score as output. A formalized procedure was used to construct the model for welfare assessment in pregnant sows on the basis of available scientific knowledge. This SOWEL (from SOw WELfare) model contains 37 attributes that describe the welfare-relevant properties of housing and management systems. In the decision support system these attributes are linked to scientific statements and a list of needs to provide a scientific basis for welfare assessment. Weighting factors that represent the relative importance of the attributes are derived from the scientific statements about the various welfare performance criteria that have been measured by scientists. The welfare score is calculated as the weighted average score. All information in the decision support system is stored in tables in a relational database such that newly available knowledge and insights can be incorporated to refine the model. The model has been developed in line with several existing models but it differs from these models in that it is the first to provide a formalized procedure to explicate the reasoning steps involved in welfare assessment based on available scientific knowledge.

Animal Husbandry↗

PubMed2002

Decision support system for overall welfare assessment in pregnant sows B: validation by expert opinion.

This paper examines the validity of a model that is embedded in a computer-based decision support system to assess the welfare status of pregnant sows in housing and management systems. The so-called SOWEL (SOw WELfare) model was constructed using a formalized procedure to identify and weight welfare-relevant attributes of housing systems in relation to the animal's needs, and evidenced by scientific statements collected in a database. The model's predictions about welfare scores for 15 different housing systems and weighting factors for 20 attributes were compared with expert opinion, which was solicited using a written questionnaire for pig-welfare scientists. The experts identified tethering and individual housing in stalls as low welfare systems. The group of midwelfare systems contained indoor group-housing systems and an individual-housing system with additional space and substrate. The five best systems were all systems with outdoor access and the provision of some kind of substrate such as straw. The highest weighting factors were given for the attributes "social contact," "health and hygiene status," "water availability," "space per pen," "foraging and bulk," "food agonism," "rooting substrate," "social stability," and "movement comfort." The degree of concordance among the experts was reasonable for welfare scores of housing systems, but low for weighting factors of attributes. Both for welfare scores and weighting factors the model correlated significantly with expert opinion (Spearman's Rho: 0.92, P < 0.001, and 0.72, P < 0.01, respectively). The results support the validity of the model and its underlying procedure to assess farm-animal welfare in an explicit and systematic way based on available scientific knowledge.

Animal Husbandry↗

PubMed2001

Chronic imipramine treatment partially reverses the long-term changes of hippocampal synaptic plasticity in socially stressed rats.

In the present study, we investigated whether synaptic plasticity changes in the hippocampus of depressive-like socially stressed rats could be reversed by chronic antidepressant treatment. To that end, rats were either defeated and subsequently individually housed or subjected to control treatment followed by social housing. After a period of at least 3 months, rats were either treated chronically with imipramine (20 mg/kg per day, per os for at least 3 months) or the solvent solution (i.e. water). Then, long-term potentiation and depression were measured in the CA1 region of the hippocampus in vitro. Chronic imipramine treatment partially restored the attenuated induction of long-term potentiation and suppressed the facilitation of long-term depression-induction in socially stressed rats. The altered synaptic plasticity after social stress is discussed in relation to cognitive deficits and hippocampal changes that are observed in depressive patients.

Animals↗

PubMed2001

Long-term impairment of social memory in the rat after social defeat is not restored by desglycinamide-vasopressin.

Repeated social defeat followed by individual housing caused a long-term impairment of social memory in male rats. Social memory, as assessed in the social discrimination test using an intertrial interval of 3 min, was impaired for at least 8 weeks after the social defeat experience. Since social memory of male rodents depends on proper functioning of the sexually dimorphic vasopressin system, it was investigated whether a centrally active vasopressin fragment could restore the impaired social memory. Subcutaneous administration of 6 microg/kg of the vasopressin fragment desglycinamide-vasopressin (VP1-8) 40 days after social defeat slightly improved social memory in both control and socially defeated rats. It is concluded that social defeat followed by individual housing caused a long-term impairment of social memory, which was not restored by treatment with VP1-8.

Animals↗

PubMed2001

Delayed effect of the vasopressin metabolite VP4-8 on the social memory of sexually naive male rats.

RATIONALE: Endogenous vasopressin is involved in the social memory of the male rat and administration of exogenous vasopressin improves social memory. These findings are mainly based on studies using sexually experienced males that were tested in the social recognition test. OBJECTIVE: The present study was aimed to establish whether the modulation of social memory by vasopressin fragments depends on the sexual experience of the male rat. For this purpose, the social discrimination test was used, since this test is more suitable than the social recognition test for measuring social memory in sexually naive males. METHODS: Male rats were tested in the social discrimination test and treated subcutaneously with the vasopressin metabolite [pGlu4,Cyt6]vasopressin-(4-8) (VP4-8). VP4-8 shares with vasopressin the effects on memory processes but lacks the peripheral effects of vasopressin. RESULTS: VP4-8 (1 microgram/kg) acutely improved the social memory of sexually experienced male rats, confirming previous reports. However, in sexually naive males VP4-8 failed to improve social memory in doses ranging from 0.1 microgram/kg to 1 microgram/kg. Instead, 1 microgram/kg VP4-8 or 6 micrograms/kg desglycinamide-vasopressin were found to exert a delayed effect in sexually naive rats. This delayed effect resulted in an improved social memory 2 days after administration. CONCLUSIONS: Vasopressin sensitisation is discussed as a possible underlying mechanism of the observed delayed effect of vasopressin fragments. It is concluded that in male rats sexual experience can influence the modulation of social memory by vasopressin.

Age Factors↗

PubMed2001

Social memory in the rat: circadian variation and effect of circadian rhythm disruption.

Disruption of circadian rhythm can impair long-term passive avoidance memory of rats and mice. The present study investigated whether disruption of circadian rhythm can also impair social memory of male rats. Social memory was assessed using the social discrimination test, in which a short-term olfactory memory is formed by social interaction with a juvenile rat during a learning trial. After an intertrial interval, a retrieval trial is performed, in which social memory is expressed as a decreased attention paid to the same juvenile as compared to a new juvenile. First, the social memory at four different time points across the light-dark cycle was measured with an intertrial interval of 10 or 25 min. There was no significant circadian variation of social memory across the light-dark cycle. Subsequently, the effect of a -6 or 12-h phase shift on social memory was studied. These phase shifts were previously found to impair long-term passive avoidance memory. However, no effect of either phase shift was observed in the social discrimination test. It is concluded that the disruption of circadian rhythm had no effect on the social memory of rats. Differences between short-term social memory and long-term passive avoidance memory are discussed in relation to their apparent differential susceptibility to the effects of circadian rhythm disruption.

Animals↗

PubMed2000

Defeat followed by individual housing results in long-term impaired reward- and cognition-related behaviours in rats.

In contrast to the well-documented acute effects on behavioural sensitivity, chronic effects that persist for weeks or even months after the cessation of the stressor received relatively little attention. This study aimed at the long-term effects of a severe stressor, i.e. social defeat followed by individual housing. Defeated and subsequently individually housed animals displayed impaired social memory, decreased social interaction and diminished anticipation for a sucrose solution for up until a period of 3 months after defeat. Remarkably, social housing counteracted the defeat-induced effects. The impaired capability to anticipate for a reward was discussed in relation to anhedonia, an important symptom of human depression. Moreover, the disturbed memory, the chronic nature of the effects, and the therapeutic effects of social housing, suggest that the defeat model may serve as a potential model for human psychopathology.

Analysis of Variance↗

PubMed2000

Morphine attenuates the effects of juvenile isolation in rats.

The acute effects of juvenile isolation on sucrose intake and its long-term consequences on adult social behavior were investigated. Additionally, the role of the endogenous opioid systems was studied. Juvenile rats were housed in one of three conditions: in groups or in isolation with (partial isolation, PI) or without 30 min of daily social contact from 22 to 35 days-of-age. During this period the rats were treated daily with saline or morphine. Juvenile isolated rats showed an increased sucrose intake as compared to non-isolated controls, with PI-rats somewhere in-between, suggesting a negative correlation between the amount of social contact and sucrose consumption. Morphine treatment during the isolation period enhanced the sucrose intake in non-isolated rats, whereas it decreased sucrose consumption in (partial) isolated rats. With regard to the long-term effects, (partial) isolated rats decreased social activity as compared to non-isolated controls which was reversed by morphine treatment during the isolation period. In non-isolated rats, morphine treatment caused an opposite effect: it decreased social activity as compared to the saline treated controls. The data suggest that stimulation of endogenous opioid systems in the juvenile phase may have an important modulatory role in the expression of adult social behavior. The results are discussed in relation to a possible function of morphine as a substitute for the release of endogenous opioid peptides during social play.

Animals↗

PubMed2000

Differential responses of phosphorylated mitogen-activated protein kinase and phosphorylated cyclic-AMP response element-binding protein immunoreactivity in the rat brain to sub-convulsive pentylenetetrazol.

The possible advantage of using multiple phospho-specific antibodies to study changes in brain activity was assessed. For this purpose, rats were injected intraperitoneally with either a control treatment or 15 mg/kg pentylenetetrazol. The sub-convulsive dose of pentylenetetrazol did not induce marked behavioural effects. Ten minutes after treatment, the rats were perfused and the brains were dissected. Adjacent brain sections were immunohistochemically stained for phosphorylated cyclic-AMP response element-binding protein and phosphorylated mitogen-activated protein kinase. Opposite effects of pentylenetetrazol treatment were observed on the immunoreactivity of these two antibodies within the hypothalamic paraventricular nucleus, the supraoptic nucleus and the arcuate nucleus. In these regions, pentylenetetrazol treatment increased phosphorylated mitogen-activated protein kinase immunoreactivity, but decreased phosphorylated cyclic-AMP response element-binding protein immunoreactivity. These findings show that changes in the activity of a brain nucleus can be accompanied by differential changes in the activity of two signal transduction pathways, which can be detected immunohistochemically. Therefore, the use of multiple phospho-specific antibodies may enhance our potential to monitor changes in brain activity.

Animals↗