tickling-a-technique-for-inducing-positive-affect-when-handling-rats

Tickling, a Technique for Inducing Positive Affect When Handling Rats

Handling small animals such as rats can lead to several adverse effects. These include the fear of humans, resistance to handling, increased injury risk ...

Washington State University

Canadian Council on Animal Care

Worm-running is behaviour in which a chick runs carrying a worm-like object while flock mates follow and attempt to grab the object from its beak. We hypothesised that social ranks based on worm-running frequency are stable over time and are positively correlated with social ranks based on success in aggressive interactions when older. At 8-12 days of age, we scored worm-running in 17 groups of 12 female White Leghorn chicks during three 10-min tests. Based on instantaneous scans at 5-s intervals, the bird carrying the 'worm' most often was placed in rank one and so on down the rank order. These tests were repeated at 68-70 days of age. An aggression index for each bird was calculated as the number of aggressive acts given, divided by the number given and received, during three 1-h observation periods when the birds were 68-70 days. Ranks obtained in worm-running tests were positively correlated over the two age periods (P < 0.05) but were not correlated with ranks based on the aggression index (P > 0.05). Our results indicate that worm-running ranks are not predictive of success in aggressive interactions. Instead, worm-running fits some criteria for play.

Comparison of social ranks based on worm-running and aggressive behaviour in young domestic fowl.

Gamma-hexachlorocyclohexane (lindane) is a pesticide with the potential to produce long-term effects on fear or anxiety due to its targeting of the GABA(A) receptor in the brain. Multiple chemical sensitivity (MCS) is a human condition that has been attributed to repeated chemical exposures, with pesticides heavily implicated in the initiation of MCS. The symptoms in MCS patients are wide ranging but prominent among these in a subset of patients is increased evoked panic responses. Drawing a parallel between these responses in MCS patients and a panic model in rats, these studies explored a potential animal model for MCS. The effects of repeated lindane exposure on conditioned fear behavior was examined in adult male Sprague-Dawley rats. Animals were administered vehicle or lindane (intraperitoneally) for either 3 days/week (1, 2 or 5mg) or 5 days/week (2mg) over 2 weeks, and 18 days later were examined for anxiety levels on an elevated plus-maze. One day later, animals were trained for fear conditioning to an odor conditioned stimulus (CS). Freezing behavior was measured 1 day later in the context where pairing occurred, and then for a total of 6 days in a different environment in which either no CS or the CS was presented. After a second 18-day period of no treatment, rats were again tested for their freezing response to the CS for 2 days. Lindane pretreatment did not alter elevated plus-maze performance, nor did it alter contextual freezing behavior. However, pretreatment with lindane decreased the extinction of fear conditioning to the CS such that freezing behavior in controls was significantly lower than in lindane-pretreated rats, and this effect persisted during testing 18 days later. The results indicate that repeated low-level lindane exposure may produce long-lasting changes in anxiety-related neural circuitry. This suggests that odor-triggered symptoms associated with an aversive event may persist in MCS patients because of the ability of some chemicals to alter fear or anxiety circuitry in the brain.

Low level lindane exposure alters extinction of conditioned fear in rats.

The domestic pig (Sus scrofa domesticus) has been proposed as an animal model for human alcoholism because pigs have been observed to consume alcohol voluntarily to a state of intoxication and to exhibit tolerance and physical dependence. However, it has not been established whether pigs can develop psychological dependence on alcohol. We hypothesised that feed-restricted, stall-housed pregnant sows fed alcohol non-voluntarily for 5 weeks would develop a preference for alcohol and retain this preference after removal of alcohol from the diet. We fed crossbred commercial sows (n=10) 280 ml of 95% ethanol mixed with 0.91 kg of feed and 720 ml of water twice daily for 5 weeks during the first trimester of pregnancy. Control sows (n=7) received dextrose in their feed as a caloric control, and water was added to give the feed a consistency similar to that of the alcohol-treated feed. Immediately before and after 5 weeks of alcohol or dextrose treatment and 3 weeks later, after termination of alcohol or dextrose treatment, we evaluated sow diet preference by comparing the amount of alcohol-supplemented, dextrose-supplemented and plain feed consumed during a 5-min choice test. Contrary to our hypothesis, there was no treatment effect on sow diet preference. Both alcohol-treated and control sows ate less of the alcohol diet than the other two diets in all choice tests. They did not discriminate between the plain and dextrose diets. We conclude that 5 weeks of non-voluntary consumption of alcohol in feed did not produce a preference for alcohol in pregnant sows, either during treatment or after withdrawal, thus providing no evidence for the development of psychological dependence on alcohol under these conditions.

Article	Year
Comparison of social ranks based on worm-running and aggressive behaviour in young domestic fowl. Behavioural processes\| PubMed ID: 14744549	2004
Low level lindane exposure alters extinction of conditioned fear in rats. Toxicology\| PubMed ID: 16213647	2006
Consumption of alcohol by sows in a choice test. Physiology & behavior\| PubMed ID: 16631215	2006

Sylvie Cloutier

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