The effect of neonatal handling on adult feeding behavior is not an anxiety-like behavior.

Testing whether anxiety explains an early-life effect on sweet-food intake

Brief neonatal handling had been found to increase adult rats’ consumption of palatable food. Because stress and anxiety can also influence eating, this experiment asked whether the feeding effect was simply an expression of greater anxiety.

Using behavior and a drug challenge to test the explanation. Newborn rats were left undisturbed, handled for ten minutes a day, or handled with additional tactile stimulation during the first ten days of life. As adults, they completed several tests of exploration and anxiety-like behavior, including an elevated maze, a light–dark box and an open field. Sweet-food intake was also measured after diazepam or a control injection.

Diazepam was used because of its anxiety-reducing action. If the increased intake depended on the anxiety mechanism targeted by the drug, a change in feeding after treatment would have helped support that explanation.

The results did not support a simple anxiety account. Both handled groups ate more sweet food than undisturbed controls. Yet their performance did not show a consistent increase in anxiety across the behavioral tests. Handled animals made more crossings in some exploration tests, while performance in the elevated maze did not differ by handling. Diazepam did not change the increased sweet-food consumption under the conditions tested.

These findings argue against interpreting the feeding difference as straightforward anxiety-related eating. They directed attention toward other lasting changes in how palatable food is processed, including reward and feeding-regulation systems.

The experiment rules against a particular explanation within its test conditions; it does not show that anxiety never influences eating or identify the alternative mechanism by itself. Its contribution is the deliberate use of multiple behavioral measures and a pharmacological test to narrow the interpretation of an early-life effect.