Both conditioned taste preference and aversion induced by corticotropin-releasing factor

Area of Science:

• Neuroscience
• Behavioral Endocrinology
• Pharmacology

Background:

• Conditioned flavor aversion is a learned suppression of intake for a novel flavor following illness.
• Stress hormones, like corticotropin-releasing factor (CRF), influence behavioral and hormonal responses to stress.
• The role of CRF in conditioned taste aversion (CTA) learning is not fully understood.

Purpose of the Study:

• To investigate the effects of central administration of CRF on conditioned taste aversion in rats.
• To determine if CRF can induce both taste preference and aversion in a dose-dependent manner.

Main Methods:

• Rats were administered CRF intracerebroventricularly (ICV) after tasting a saccharin solution.
• Two-bottle choice tests (water vs. saccharin) were used to measure saccharin consumption.
• Dexamethasone pretreatment was used to explore the neurotropic actions of CRF.

Main Results:

• A low dose of CRF (0.5 µg ICV) significantly increased saccharin consumption after a single pairing, indicating taste preference.
• A higher dose of CRF (5 µg ICV) abolished saccharin intake after two pairings, demonstrating taste aversion.
• Dexamethasone pretreatment attenuated but did not eliminate CRF-induced conditioned taste avoidance, suggesting direct neurotropic effects.

Conclusions:

• Exogenous CRF can induce both conditioned taste preference and aversion in rats, depending on the dose and experimental context.
• Low doses of CRF may promote arousal leading to taste preference, while higher doses elicit aversive effects.
• The aversive effects of CRF appear to be mediated, at least in part, by direct neurotropic actions.