Defense reaction induced by a metabotropic glutamate receptor agonist microinjected into the dorsal periaqueductal gray of rats

Author(s)

M.L. Molchanov ^[1] ; F.S. Guimarães ^[2]

Affiliation

^[1] Universidade de São Paulo - Brasil

^[2] Universidade de São Paulo - Brasil

• Document type: Journal article
• Source: Brazilian Journal of Medical and Biological Research; v. 32, n. 12, p. 1533-1537, 1999-12-00.

Abstract

The behavioral effects of trans-(±)-1-amino-1,3-cyclopentanedicarboxylic acid (t-ACPD), a metabotropic glutamate receptor (mGluR) agonist, or 0.9% (w/v) saline, injected into the dorsal periaqueductal gray (DPAG), was investigated. Male Wistar rats showed defense reactions characterized by jumps toward the top edges of the cages (saline = 0 vs t-ACPD = 6.0, medians P<0.05) and gallops (saline = 0 vs t-ACPD = 10.0, medians P<0.05) during the 60-s period after the beginning of the injection. In another experiment animals were placed inside an open arena for 5 min immediately after injection. Their behavior was recorded by a video camera and a computer program analyzed the videotapes. Eleven of fifteen rats injected with t-ACPD showed a short-lasting (about 1 min) flight reaction. No saline-treated animal showed this reaction (P<0.0005, chi-square test). The drug induced an increase in turning behavior (P = 0.002, MANOVA) and a decrease in the number of rearings (P<0.001, MANOVA) and grooming episodes (P<0.001, MANOVA). These results suggest that mGluRs play a role in the control of defense reactions in the DPAG. (AU)

• FAPESP's process: 98/10639-7 - Neurobiology of Behavioral responses to aversive events
• Grantee: Francisco Silveira Guimaraes
• Support Opportunities: Research Projects - Thematic Grants