Abstract
Gentle tactile stimuli have been shown to play an important role in the establishment and maintenance of affiliative social interactions. Oxytocin has also been shown to have similar actions. We investigated the effects of gentle stroking on affiliative relationships between humans and rats and the effects of gentle stroking on activation of oxytocin neurons. Male rats received 5-min stroking stimuli from an experimenter every other day for 4 weeks between 3 and 6 weeks of age (S3–6 group), for 4 weeks between 7 and 10 weeks of age (S7–10 group), or for 8 weeks between 3 and 10 weeks of age (S3–10 group). Control rats did not receive stroking stimuli. Rats in the S7–10 and S3–10 groups emitted 50-kHz calls, an index of positive emotion, more frequently during stroking stimuli. Rats in the S3–6, S7–10, and S3–10 groups showed affiliative behaviors toward the experimenter. Oxytocin neurons in the hypothalamic paraventricular nucleus of rats in the S3–6, S7–10, and S3–10 groups were activated following stroking stimuli. These findings revealed that post-weaning repeated stroking stimuli induce an affiliative relationship between rats and humans and activation of oxytocin neurons.
Highlights
Gentle tactile stimuli have been shown to play an important role in the establishment and maintenance of affiliative social interactions
Post-weaning stroking stimuli for more than 4 weeks facilitated emission of 50-kHz calls, FM-calls, which have been shown to be associated with positive emotional states20, and induced following behavior toward the experimenter’s hand
The results showing that stroking stimuli activated oxytocin neurons in the hypothalamus are consistent with the view that oxytocin plays an important role for an affiliative relationship between conspecifics such as mother-infant or male and female pairs and interspecific animals including humans and rats
Summary
Gentle tactile stimuli have been shown to play an important role in the establishment and maintenance of affiliative social interactions. Non-FM 50-kHz calls have been shown to be emitted during non-social situations such as feeding behavior25 These behavioral characteristics are useful for clarifying affiliative relationships between humans and rats in experimental situations. Tactile stimulation has been suggested to play a fundamental role in the establishment and maintenance of intimate relationships between individuals Positive physical contacts such as hugging and massage by partners have been shown to reduce cortisol release and heart rate increase in response to stressful stimuli in humans. We have shown that massage-like gentle stroking stimuli induce 50-kHz calls in rats. We have shown that massage-like gentle stroking stimuli induce 50-kHz calls in rats29 It was not known whether stroking stimuli induce an affiliative relationship between rats and humans. We considered that stroking stimuli activate oxytocin neurons and contribute to an affiliative relationship between humans and rats
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call