From the book "The Social Autist" https://www.amazon.com/Social-Autist-Autists-Allocentric-Universe-ebook/dp/B09JSQ42TR

Chapter 7

Oxytocin and Vasopressin

1.1 Oxytocin

Oxytocin is a neuropeptide that has pro-social effects on the brain[12] as well as many other effects on the brain and body. It has been around for an estimated 700 million years and is Greek for “fast birth” because of it's ability to induce labor. It serves a dual role as a neurotransmitter/neuromodulator and a hormone. It doesn't affect emotions but rather approach-related behaviours[14] in the brain. It is the most well studied mammalian system. Here is a list of what we know oxytocin affects:

Oxytocin Effects

Brain

a)Approach-related behaviours

b)Trust(initial betrayal aversion)

c)Generosity

d)Affective(emotional) speech comprehension

e)Attachment

f)Anxiolytic

g)Female sexual desire and orgasm intensity

h)Male orgasm

i)Reflexive visual attention(gaze, reading the mind in the eyes, reading facial expressions)

j)Memory acquisition and spatial memory(remembering faces, names, shapes, etc)

Body

a)Stress relief(cortisol attenuation)

b)Labor induction

c)Stimulates gastric emptying and colonic peristalsis(moving stuff in waves)

d)Milk let-down

As you can see, a lot of these things are directly responsible for what is deemed autism and explain it from a physiological standpoint. Studies showed that autists with low blood plasma oxytocin improved socially by taking intranasal oxytocin. So for some autists, this is a way to cheat evolution and have the allistic experience. I've experimented with taking intranasal oxytocin and logged a diary of my experience in Appendix A. It will suffice to say that it worked extremely well for me and in ways I could not have imagined.

As an evolutionary mechanism, oxytocin allows us to overcome our innate instinct to stay away from others. Without it, we would all be like reptiles or cats, only coming together to reproduce or fight over territory; or in the case of human autism, to have intellectually stimulating interactions. If you could point to one thing that screams autism, it's the oxytocin system.

Oxytocin can normally be produced by humans and it increases when pressure is applied to the skin, and is most stimulated through manipulation of the nipples. This is why weighted blankets work if you don't have a person to cuddle, hug, or have sex with. Oxytocin is released when your stomach gets full. It's the brain rewarding you for eating. If you're like me and forget to eat, now you know why. Another way to alter oxytocin is to upregulate the CD38 gene by consuming all-trans retinoic acid, which is currently under investigation.

One last way to get oxytocin is by intranasal spray. It's over-the-counter where I live and very inexpensive. It travels up the vagus nerve into the brain. Don't bother with any other method because it does not cross the blood-brain barrier sufficiently.

1.2 Vasopressin

Arginine Vasopressin(AVP) is a neuropeptide that acts both as a neurotransmitter and a hormone. It mediates complex mammalian social behaviors such as pair bonding, social recognition, aggression, and causally increases humans' willingness to engage in risky, mutually beneficial cooperation[4]. Here are the things we know about how AVP affects us:

Vasopressin Effects

Brain

a)Social Monogamy

b)Affiliation

c)Aggression

d)Paternal/Maternal behaviours

e)Willingness to engage in risky cooperation

f)Enhances short term memory

Body

a)Raises blood pressure

b)Thirst

c)Water balance

d)Secrete stress hormone ACTH

e)Conservation of fluids for lactation

f)Premature birth from stress

Normally, AVP increases in males after mating which triggers mate-guarding and territorialism. The effects are much stronger in males because testosterone enhances the effects.

Some autists are helped by taking intra-nasal AVP, and some are helped by blocking AVP with balovaptan. So you can see how an excess or deficiency would cause many symptoms of autism, especially when combined with oxytocin deficits.

1.3 Oxytocin-Vasopressin Pathway

You can combine oxytocin and vasopressin to get different effects as seen in the following graphic: https://www.frontiersin.org/files/Articles/322440/fendo-08-00356-HTML/image_m/fendo-08-00356-g002.jpg

You can also take into account the context of the situation to get the type of emotions evoked as shown in the following graphic(the arrows with both up and down indicate fluctuating increases and decreases): https://www.frontiersin.org/files/Articles/322440/fendo-08-00356-HTML/image_m/fendo-08-00356-g003.jpg

We could call these fight/flight/freeze responses although they are the mental version.

Starting from the left, we have more oxytocin than AVP in a safe or loving context so we stay there without fear. As we move to the right, we have a large increase in oxytocin and AVP in an acute fearful situation so we freak out and run. Then it's the same thing in the next one but oxytocin is reduced. The last one has fluctuating increases and decreases of oxytocin and AVP in a traumatic fearful situation so we freak out and hide or become bystanders around a person bleeding to death.

It's obvious that this system evolved for social and reproductive reasons. It's also another mechanism by which a person can be emotionally manipulated by an external event. It's great to have a person lacking in this when everybody else is frozen in fear or laying about all day having sex, but it sucks when trying to find love, enjoy sex, and socialize(unless you know how to mitigate it).

[4] Claudia Brunnlieb, Gideon Nave, Colin F. Camerer, Stephan Schosser, Bodo Vogt, and M Thomas F. Vasopressin increases human risky cooperative behavior. Proceedings of the National Academy of Sciences, 113(8):2051–2056, February 2016.

[12] Madelon M.E.RiemabMarian J.Bakermans-KranenburgabRenskeHuffmeijerabMarinus H.van IJzendoorn. Does intranasal oxytocin promote prosocial behavior to an excluded fellow player? a randomized-controlled trial with cyberball. Psychoneuroendocrinology, 38(8):1418–1425, August 2013.

[14] Andrew Kemp. Oxytocin: prosocial behavior, social salience, or approach-related behavior? Biological Psychiatry, January 2010.