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Light-enhanced startle: further pharmacological and behavioral characterization
David L Walker1, Michael Davis
1Department of Psychiatry and Behavioral Sciences and the Center for Behavioral Neurosciences, Emory University School of Medicine, Woodruff Memorial Building, Suite 4000, 1639 Pierce Drive, Atlanta, GA 30322, USA. dlwalke@emory.edu
Psychopharmacology
|February 28, 2002
Summary
Bright light increases startle response in rats, suggesting anxiety. Both chlordiazepoxide and propranolol reduced this light-enhanced startle, supporting the anxiety link. Handling did not affect the response.
Area of Science:
- Neuroscience
- Behavioral Science
Background:
- Acoustic startle response is elevated in bright light, potentially reflecting an anxious state.
- This light-enhanced startle is disrupted by buspirone, a 5HT1A agonist and D2 antagonist.
- Pre-test handling may influence light-enhanced startle.
Purpose of the Study:
- To further characterize light-enhanced startle.
- To evaluate the effects of chlordiazepoxide and propranolol on light-enhanced startle.
- To determine the role of pre-test handling in light-enhanced startle.
Main Methods:
- Rats were tested for acoustic startle in dark and light conditions after IP injections.
- Chlordiazepoxide (5-20 mg/kg) and propranolol (10-20 mg/kg) were administered.
- The effect of pre-test handling (handling, no handling, no delay) was assessed.
Main Results:
- Chlordiazepoxide and propranolol disrupted light-enhanced startle at comparable doses to fear-potentiated startle.
- No significant effect of handling on light-enhanced startle was observed.
Conclusions:
- Results support the hypothesis that light-enhanced startle is influenced by anxiety.
- The findings further characterize the pharmacology of light-enhanced startle.
- Procedural variables like handling do not appear to influence this behavior.