Effects of ganglionic blocking agents on behavioral responses to centrally administered CRF

The ganglionic blocking agents, chlorisondamine (CL) and hexamethonium (HEX) were used to examine the role of altered autonomic function in the behavioral response to i.c.v.-administered corticotropin-releasing factor (CRF). Animals were tested in either a novel modified open field or in their home cages. CRF-induced alterations in locomotion, grooming and eating were assessed in both environments in the presence or absence of CL or HEX. In the home cage the ability of CRF to increase grooming was attenuated by pretreatment with either CL or HEX. In the modified open field only HEX significantly suppressed grooming. In the familiar environment CRF-induced increases in locomotion were significantly inhibited by CL. However, in a novel environment, where CRF suppresses locomotion, CL was inactive. The competitive ganglionic nicotinic blocking agent, HEX, on the other hand, inhibited both the increased locomotion produced by CRF in the home cage and also the decreased locomotion induced by CRF in the modified open field. CRF suppression of food consumption was attenuated by CL. These results indicate that while centrally-mediated activation of the sympathetic nervous system cannot account for the full magnitude of the behavioral effects of i.c.v. CRF, such activation may play a part in both the locomotor activating components of the CRF response seen in the familiar environment as well as the suppressive effects seen in the novel environment.