Porphyrin biosynthesis in human Barrett's oesophagus and adenocarcinoma after ingestion of 5-aminolaevulinic acid

5-Aminolaevulinic acid (ALA)-induced porphyrin biosynthesis, which is used for ALA-based photodynamic therapy (ALA-PDT), was studied in tissues of 10 patients with Barrett's oesophagus (BE) and adenocarcinoma of the oesophagus (AC) undergoing oesophagectomy at a mean time interval of 6.7 h after the ingestion of ALA (60 mg kg(-1)). In BE, AC, squamous epithelium (SQ) and gastric cardia, the activities of the haem biosynthetic enzymes porphobilinogen deaminase (PBG-D) and ferrochelatase (FC) and the PDT power index--the ratio between PBG-D and FC in BE and AC in comparison with SQ--were determined before ALA ingestion. Following ALA administration, ALA, porphobilinogen, uroporphyrin I and PPIX were determined in tissues and plasma. The PDT power index did not predict the level of intracellular accumulation of PPIX found at 6.7 h. In BE, there was no selectivity of PPIX accumulation compared to SQ, whereas in half of patients with AC selectivity was found. Higher haem biosynthetic enzyme activities (i.e. PBG-D) and lower PPIX precursor concentrations were found in BE and AC compared to SQ. It is therefore possible that PPIX levels will peak at earlier time intervals in BE and AC compared to SQ.

Opioid peptides and behavioral and physiological responses of dairy cows to social isolation in unfamiliar surroundings

To test whether endogenous opioid peptides are involved in the behavioral and physiological responses of cattle to stress, 12 Holstein cows were either placed in social isolation in unfamiliar surroundings for 15 min or remained in their home stalls, either with or without naloxone treatment, following a Latin square design. Vocalizations (judged as high or low frequency), defecation/urination, and heart rate were recorded, latency to respond to local thermal stimulation of the leg by means of a laser was measured to detect pain sensitivity, and blood was sampled and assayed for cortisol concentrations. Naloxone in the home stall increased cortisol concentrations and tended to reduce response latencies to the laser but did not induce vocalization. Social isolation increased the incidence of high-frequency vocalization and of defecation/urination, heart rate, cortisol concentrations, and response latencies to the laser. Prior administration of naloxone increased the incidence of low-frequency vocalization in isolation, but it had no effect on heart rate or on responses to the laser and only limited effect on cortisol concentrations when the cows were isolated. Brief periods of social isolation in unfamiliar surroundings seem to be stressful to cows, as indicated by increased heart rate, hypothalamic-pituitary-adrenocortical axis activity, and vocalization. Isolation also reduces pain sensitivity, suggesting a stress-induced analgesia. However, we found no evidence that naloxone-sensitive opioid receptors were involved in these responses.

Effect of intracerebroventricular administration of vasopressin on stress-induced hyperthermia in rats

Vasopressin has been reported to be an endogenous antipyretic peptide. The present study assessed whether this peptide has similar effects on stress-induced hyperthermia. Infusion of 3 ng of vasopressin into the lateral ventricle prior to a 40-min restraint stress reduced significantly the hyperthermic response of rats to this stress, compared to saline-injected controls. Half of the vasopressin-injected animals showed an immediate hypothermic response, with a significant reduction in body temperature of 0.34 degree C or more within 10 min; however, the effect of vasopressin on stress-induced hyperthermia remained significant after exclusion of these animals from the analysis. Administration of a V1 receptor antagonist prior to the stress did not affect the hyperthermic response, which may suggest that the hyperthermic response had reached maximal (ceiling) levels. Administration of vasopressin, or of the V1 receptor antagonist immediately after the stress, did not affect defervescence, suggesting that vasopressinergic systems are not implicated in the defervescence process. Thus, the results show that ICV administration of vasopressin reduces stress-induced hyperthermia. The mechanisms underlying the effects remain to be elucidated.

A review of behavioral factors involved in the development and continued performance of stereotypic behaviors in pigs

Environmentally induced stereotypies, commonly observed in farm and zoo animals, are behaviors that are relatively invariant, that are regularly repeated, and that serve no obvious function. However, there is as yet no accepted means of discriminating between normal and abnormal behavior, and the assumption that stereotypies are abnormal may mask the fact that they arise in part through processes that "normally" control behavior. There is growing evidence that stereotypies in sows and broiler breeders are strongly related to feeding motivation. For example, sows only develop oral stereotypies if their feed intake is restricted, and operant conditioning experiments have shown commercial levels of feed restriction to give rise to high levels of feeding motivation. Stereotypies in animals whose feed intake is restricted largely occur in the postprandial period, and ingestion of food has specifically been shown to elicit stereotypies in sows. These observations suggest that positive feedback from feeding produces a short-term increase in feeding motivation that at the end of the meal is directed toward available, alternative stimuli such as chains, the choice of stimuli reflecting the sensory feedback from the activity. Drinking behavior may also become an expression of feeding behavior after metabolic water requirements are met. In addition to these processes specific to feeding motivation, it seems likely that nonspecific processes, which operate more generally across motivational systems, contribute to the persistence of the behavior. Behavioral arousal may facilitate performance of active behaviors, and sensitization of the underlying neural elements may lead to the behavior being more easily elicited and maintained. A crucial factor in the sensitization process would seem to be the channeling of complex behavior by the environment into a few and very often repeated sequences of behavior. This approach suggests that stereotypies can be prevented by either reducing the level of motivation underlying the stereotypy, or by allowing for the expression of more complex behavior and thereby preventing the processes of channeling and sensitization from occurring.

Relationship between feeding, stereotypies, and plasma glucose concentrations in food-restricted and restrained sows

Previous work has shown that stereotypies, such as chain manipulation and excessive drinking, only develop in food-restricted sows. Furthermore, once stereotypies have been developed, ingestion of a small meal specifically stimulates the performance of stereotypes. These results suggest that the occurrence of stereotypies may strongly depend on the individual's nutritional status. As glucose is one of the main metabolic fuels, the present experiment investigated whether individual differences and/or daily variations in levels of chain manipulation and excessive drinking are correlated to individual differences and/or daily variations in pre- or postfeeding glucose concentrations. Blood samples were taken at regular intervals prior to, during, and after feeding, from sows that had developed stereotypies to different degrees over a period of 110 days of restrictive housing and feeding conditions. Glucose concentrations were low prior to and high after feeding. Levels of stereotypies showed similar variations, suggesting that the performance of stereotypies is not related to low glucose concentrations. Furthermore, whilst sows differed consistently in glucose concentrations, no correlations were found between individual glucose concentrations and stereotypies. Similarly, no correlations were found between glucose concentrations and chain manipulation or drinking on a sample to sample basis. These data show that although performance of stereotypies is strongly dependent on feeding regime, it is not related to plasma glucose concentrations.

The behavioural effects of undernutrition in confined farm animals

Results suggest that where the animal is unable to engage in functional feeding to reduce nutrient deficit, it may still continue to engage in feeding by directing its feeding behaviour to other alternative stimuli. If feeding is to be maintained where there are constraints on further intake, the alternative stimuli to food must be of sufficient incentive to prevent feeding being inhibited by other tendencies. Alternatives to food then are likely to be chosen on the basis of their sensory (incentive) qualities, and the precise form of feeding behaviour will depend on the interaction between the feeding tendency and the choice of available stimuli. Growing pigs offered single diets ad lib. and experiencing relatively mild deficits of specific-nutrients, may direct this behaviour towards pen-mates as alternative foraging stimuli, with blood resulting from this foraging activity acting as a further incentive to sustain the behaviour. If specific-nutrient deficits in growing pigs are generally mild then feeding may only be sustained in the presence of high incentives such as pen-mates. However, it is not always clear why stimuli such as pen-mates continue to attract foraging activity when they provide little of the deficient nutrients underlying the behaviour. Where the nutrient deficit is more extreme, such as in food-restricted sows and broiler breeders even stimuli with low incentive (e.g. chains, bars or walls) may be sufficient to maintain feeding tendency. The environment, by only allowing simple and non-complex behaviour to be performed, channels the expression of feeding behaviour into simple and repetitive stereotypic behaviours. Other behavioural processes such as arousal and sensitization may facilitate the marked persistence of stereotypies.

Behavioural responses to amphetamine and apomorphine in pigs

The effects of different doses of amphetamine (0-1.5 mg/kg) and apomorphine (0-1.0 mg/kg) on behaviour of pigs were compared. Amphetamine induced an increase in levels of nosing and rooting and of locomotion. These increases were, however, related to increased levels of standing. At higher doses (1.0-1.5 mg/kg), amphetamine specifically induced a rigid standing posture with jerking head and limb movements. Apomorphine at 0.1-1.0 mg/kg increased locomotion. In contrast to amphetamine, this effect was specific as it was not explained by increased levels of standing. At 1.0 mg/kg, apomorphine specifically induced "locomotion while the pigs maintained snout contact with the floor or trough." In addition, at this dose it induced drinking in one test, while licking in another. These differences may in part be due to differences in the test environment. Apomorphine exerted a strong conditioning effect, as indicated by the lack of behavioural variability in the postinjection period. This effect may explain the large interindividual variation in apomorphine response. Amphetamine and apomorphine elicit different behavioural syndromes in pigs, suggesting that they act on different neural systems. In addition, neither amphetamine nor apomorphine elicited behaviour that closely resembles environmentally induced stereotypies.

Relationship between amphetamine and environmentally induced stereotypies in pigs

The study investigated the relationship between the behavioural response to a standard dose of amphetamine and environmentally induced stereotypies in pigs. There were large individual differences in the frequency of amphetamine-induced stereotypies and time spent in locomotion. In addition, these two measures tended to be negatively correlated to each other, indicating that they were competitive. Levels of amphetamine stereotypies were negatively correlated with those of chain manipulation and drinking after a period of 50 and 100 days of physical restraint and food restriction; levels of locomotion were positively correlated with levels of chain manipulation after 100 days of restraint and restrictive feeding. These results suggest that pigs differ in their predisposition to develop environmentally induced stereotypies, and that this is related to catecholaminergic systems in the brain. In an amphetamine test performed after the period of restraint and restrictive feeding, amphetamine stereotypies were generally higher than in the first test but behaviour was no longer correlated to previous levels of environmentally induced stereotypies. The qualitative differences between the two forms of stereotypy, their negative rather than positive correlation, and the lack of correlation between environment-dependent stereotypies and stereotypies in the second amphetamine test suggests a complex relationship between these two forms of stereotypies. The increased amphetamine sensitivity in the second amphetamine test may reflect the effect of stress on central catecholaminergic systems.

Relationship between agonistic behaviour and propensity to develop excessive drinking and chain manipulation in pigs

Consistent individual differences in animals' responses to different stressful situations may indicate the involvement of a single behavioural and neurological mechanism across these situations. Two replicate groups of sixteen food restricted pigs were subjected to a group feeding competition test where group members were required to compete over a food source. All agonistic interactions were scored and ranked dominance scores were calculated. The pigs were subsequently put into two different forms of restrictive housing (restraint or loose), with half of the pigs food restricted. No housing effects were found. Only food restricted pigs developed excessive drinking and chain manipulation, but large individual differences existed. Pigs ranked high in dominance score were found to significantly increase their drinking levels over the experimental period of three months, having significantly higher drinking levels than low ranking pigs in the second and third month. No significant relationship was found between ranked dominance score and levels of chain manipulation. The present results suggest that in pigs differences in the propensity to develop forms of excessive drinking under restrictive housing and feeding conditions are related to agonistic tendencies in a group feeding competition test. These data also suggest that excessive drinking and chain manipulation are at least in part based on different behavioural and presumably neural mechanisms.