Comprehensive Behavioural Analysis of Rats Received Repetitive Tactile Stimulation During the Periadolescent Period.

Background: Tactile stimulation (TS) is a positive experience that mimics maternal licking and grooming in the rat. Since the brain is extremely plastic in early life, TS during this period may modulate normal brain organisation and could enhance cognitive and/or motor abilities.

Purpose: This study is designed to evaluate the possible changes in exploratory behaviour, emotionality and learning and memory following repetitive TS during periadolescent period.

Methods: Male albino Wistar rats were grouped into control and TS groups. The TS group animals were exposed to repetitive TS (15 min/session), three times/day from postnatal day 28-43. After this, exploratory behaviour, emotionality and object recognition memory were tested using open field (OF), elevated plus maze (EPM) and novel object recognition (NORT) tests by a computerised video-tracking system.

Results: TS increased rearing number, rearing rate, total stretching, total stretching duration, stretching rate, mean speed and parallelism index in rats during the OF test. However, total distance travelled, global activity and total zone transitions were comparable in both groups during the OF test. TS significantly increased stretching duration and decreased entries to the closed arm during the EPM test. It slightly increased the percentage of time spent and distance travelled on the open arm in TS group. Total distance travelled, total zone transitions and global activity were comparable in both groups during the EPM test. TS mildly increased recognition index during NORT.

Conclusion: Tactile stimulation exposed animals demonstrated increased exploratory, risk assessment and decision-making behaviours on OF test suggesting a possible positive influence of TS on these behaviours. However, TS only mildly influenced emotionality and object recognition memory, and it did not alter general locomotor behaviours in rats.