Stressor exposure and intraventricular cholecystokinin (CCK-8) administration in the light dark box model of anxiety in CD-1 mice: Possible cross-sensitization

• Main Author: MacNeil, Glenda
• Format: Dissertation
• Language: English
• Published: ProQuest Dissertations & Theses 01-01-1996
• Subjects: Experimental psychology; Experiments; Neurology; Neurosciences; Psychology
• ISBN: 0612195430; 9780612195431

The behavioural consequences of stressor exposure and intraventricular administration of CCK-8S were evaluated in the light-dark paradigm in CD-1 mice. Exposure to 15, 30 or 60 uncontrollable footshocks significantly augmented anxiety, while only 30 minutes of restraint provoked significant behavioural alterations. Fifteen or 60 minutes of restraint produced slight, but non-significant increases in anxiety. Anxiety levels were also affected by experiential factors, such as a history of surgical stress. The intraventricular administration of 5 ng CCK-8S was ineffective at provoking anxiety on the initial test day and upon re-exposure, one week later, while 50 ng CCK-8S produced significant behavioural alterations on both occasions. Interestingly, the 25 ng dose of CCK-8S augmented anxiety upon re-exposure, but did not provoke anxiety following initial challenge. Moreover, behavioural cross-sensitization between 30 minutes of restraint stress and the 5 ng dose of CCK-8S resulted in heightened anxiogenic reactivity. Cross-sensitization was not demonstrated if mice had been exposed to uncontrollable footshock prior to CCK-8S or if CCK-8S administration preceded stressor exposure. Cholecystokinin and stressor induced anxiety likely follow from an interaction of multiple neurotransmitter/neuropeptide systems and may be exacerbated by the induction of sensitization and cross-sensitization. Such neurochemical alterations may influence sensitivity to future stressors and vulnerability to stressor-related disorders.