Rats receiving fluoride during the whole pregnancy up to the 9th day of lactation showed, when isolated at 10th day of life, a reduced rate of ultrasonic vocalizations (UV) in male pups (NaF 5.0 mg) and, in 90th days male rats, an increase of the Pre-Pulse Inhibition (PPI) with a reduction of the Peak response to the Startle stimulus given alone. Newborn rat reactivity could represent a useful and validated model in anxiety studies which could be moored with the Acoustic Startle Reflex (ASR) and PPI, appropriate models to study, in adulthood, particular neurological and psychiatric disorders showing deficits in attention and sensory-motor gating (Tourettes' syndrome, obsessive compulsive disorders, Huntington's disease and schizophrenia).