"Posting is human nature" mechanism found!

The desire for social touch is rooted in our nature.
Physical contact brings people closer together.
Holding hands, hugs, and touches are all emotional.
If language is too thin, physical contact is to carry love and happiness.
The best vehicle for empathy
.

Newborns feel secure in the arms of their parents, and parent-child contact not only relieves newborn discomfort and pain, promotes their early growth and development, but also relieves mothers’ postpartum depression and lowers cortisol levels
.

Children growing up in families that are good at expressing love with body language have less aggressive behavior
.

When faced with stress, clenched hands and a 20-second hug can lower our blood pressure and heart rate, and reduce the release of stress hormones
.

In a romantic relationship, there is a saying that goes something like this: Love and contact are inseparable, and the frequency of intimacy is highly correlated with satisfaction with the relationship and with your partner
.

Until we get old, we can still get comfort and support from physical contact.
The way to make an old urchin eat obediently, in addition to verbal encouragement, gently stroking the back can achieve greater results
.

Holding the hand of a dying person transmits powerful comforting powers, both to the dead and to the living
.

The touch of physical contact can cause a wonderful brain response, and a variety of neurohormones such as oxytocin (also known as the "love hormone"), endorphins, dopamine, and serotonin are involved, which ultimately translates into pleasurable emotions
.

However, unlike "discriminative touch" (recognizing the position, shape, force, etc.
of an object), how "pleasure touch" is transmitted from the skin to the brain has always puzzled scientists
.

Until recently, a study published in Science revealed the important role of the PROK2-PROKR2 neural pathway in the transmission of pleasurable touch.
When this pathway is defective, mice no longer derive pleasure from mouse-to-mouse contact and become social.
Fear, and even show abnormal anxiety reactions
.

The study is led by Professor Chen Zhoufeng, a Chinese scholar from Washington University in St.
Louis, as the corresponding author, and Dr.
Liu Benlong from Fudan University in Shanghai and Dr.
Qiao Lina and Dr.
Liu Kun from the Institute of Acupuncture and Moxibustion, Chinese Academy of Chinese Medical Sciences as the co-first authors
.

To study pleasant touch in mice, the first problem to overcome is to simulate the touch that may make mice feel pleasant.
The researchers gently stroked the mice with a soft brush.
Adapt to gentle stickers from humans
.

The human simulated pleasant touch was tested after a period of time.
The mice were more willing to enter the cage with a soft brush to gently touch the two cages that were connected to each other
.

Not only that, the mice that received the touch of the soft brush developed physiological changes similar to those of human "pleasure touch" - a decrease in heart rate, an increased tolerance for pain caused by elevated temperature, and a decrease in plasma cortisol concentrations
.

It shows that touching with a soft brush can indeed make mice feel pleasant, and make mice prefer to enter the cage with soft brush
.

(Probably the same as cats and dogs getting their chin scratched to produce happiness)
.

Legend: preconditioning baseline (Pre-c BL); preference test (Pref T) After establishing a pleasurable touch mouse model, the next step is to find the neural pathway of pleasurable touch conduction
.

Pleasant touch is not perceived instantaneously like discriminative touch.
Therefore, the researchers believe that the afferents of pleasant touch should be composed of neuropeptides in unmyelinated, low conduction velocity C fibers and their lamina II in the dorsal horn of the spinal cord.
G protein-coupled receptor interactions are achieved by
.

Following this line of thought, the researchers eventually targeted the PROK2-PROKR2 signaling pathway
.

When mice were stimulated by soft brush strokes, the firing activity of PROKR2 neurons in the spinal cord was most active, especially when the soft brush moved at a speed of 18-22 cm/s, too fast (37-45 cm/s) or too Slow (2-3cm/s) will reduce the discharge frequency, which is very similar to the "inverted U-shaped" discharge pattern of human C fibers
.

After specific depletion of PROKR2 neurons in the mouse spinal cord (ABL mice) or knockout of the Prok2 gene in mouse dorsal root ganglion neurons (Prok2 CKO mice), both mice were no longer biased towards entry into soft hairs In the brush cage, the effect of soft brush touch on the heart rate and pain tolerance of the mice also disappeared, proving that the PROK2-PROKR2 signaling pathway is indispensable in the process of pleasant touch conduction, and this pathway defect will lead to Pleasant loss of touch
.

After loss of pleasant touch, both ABL mice and Prok2 CKO mice showed social impairment, wild-type mice greeted strange mice when new companions appeared, and the ABL mice and Prok2 CKO mice were very apathetic and were unwilling to interact with unfamiliar mice too much
.

Legend: Three-cage social novelty test, Preference%: time of mice entering the unfamiliar mouse cage/time of mice entering the familiar mouse cage When wild-type mice stick to each other, ABL mice and Prok2 CKO The mice all expressed their refusal to be "licking mice", and if wild-type mice occasionally licked their hair for ABL mice and Prok2 CKO mice, the latter were indifferent and never "licked back"
.

Legend: The length of time when several combinations of lickers and lickers appeared: wild-type-wild-type; wild-type-ABL; ABL-wild-type; wild-type-wild-type; wild-type-CKO; CKO-wild-type Unlike ABL mice whose spinal cords were depleted of PROKR2 neurons in adulthood, Prok2 CKO mice were born PROK2-deficient
.

Perhaps due to lack of social contact from infancy, adult Prok2 CKO mice showed abnormal anxiety responses, specifically reduced time in the middle of the open field, reduced time in the light and dark boxes, and open arms in the elevated maze.
ABL mice that grew up normally when they were young and experienced major changes as they grew up did not have this anxiety response
.

Anxiety symptoms in adult Prok2 CKO mice demonstrate that loss of early social contact affects responses to stressful events in adulthood
.

Defects in the PROK2-PROKR2 signaling pathway cause mice to be reluctant to engage in social contact, similar to the early behavioral characteristics of some autistic patients.
Children with autism resist physical contact with others, but interestingly, they can massage benefits, such as improved sleep symptoms and shorter periods of inattentiveness
.

The production of pleasant touch is so important that it promotes individual mental health and the occurrence of prosocial behaviors, identifying the signaling pathway for the production of pleasant touch, and may deepen our understanding of some neurodevelopmental diseases and social dysfunction in affective disorders.
and resistance to intimacy
.

Posting is human nature, and refusing to post is not good for mental health
.

(Note: Posting without permission may also have adverse consequences) Reference [1] Liu B, Qiao L, Liu K, Liu J, Piccinni-Ash TJ, Chen ZF.
Molecular and neural basis of pleasant touch sensation .
Science.
2022;376(6592):483-491.
doi:10.
1126/science.
abn2479Copy[2]Touch for socioemotional and physical well-being: A review, https://doi.
org/10.
1016/j.
dr.
2011.
01.
001.
[3]McGlone F, Wessberg J, Olausson H.
Discriminative and affective touch: sensing and feeling.
Neuron.
2014;82(4):737-755.
doi:10.
1016/j.
neuron.
2014.
05.
001‍ | Edited by Four Five Seven |