Cross references:  
Oxytocin Receptors     Oxytocin Receptor Distribution        

73<278 OxRcpDistCite    276<278 OxRcpDistCite     

My overall comment

    Oxytocin has turned out to be much more complex than I had anticipated.  I'm afraid that I'm going to be able to relate it to my mother's Sociopathy   in only the most general, phenominological, way.     

Searching Google for "oxytocin" yields 1,670,000 claimed references. 
Oxytocin - Google Search   

Oxytocin (Wiki)   
(Note:  This Wikipedia article is quite long and very informative.  If you're interested in oxytocin, you should read the whole thing.  I'll only be copying brief excerpts here.)   
    "Oxytocin (Oxt) is a mammalian neurohypophysial hormone, (secreted by the posterior pituitary gland), that acts primarily as a neuromodulator in the brain.   


Oxytocin plays an important role in the neuroanatomy of intimacy, specifically in sexual reproduction, in particular during and after childbirth. It is released in large amounts after distension of the cervix and uterus during labor, facilitating birthmaternal bonding, and, after stimulation of the nipples, lactation. Both childbirth and milk ejection result from positive feedback mechanisms.[1]

Recent studies have begun to investigate oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, and maternal behaviors.[2] For this reason, it is sometimes referred to as the "bonding hormone". There is some evidence that oxytocin promotes ethnocentric behavior, incorporating the trust and empathy of in-groups with their suspicion and rejection of outsiders.[3] Furthermore, genetic differences in the oxytocin receptor gene (OXTR) have been associated with maladaptive social traits such as aggressive behaviour.[4]

Oxytocin has peripheral (hormonal) actions, and also has actions in the brain. Its actions are mediated by specific, high-affinity oxytocin receptors. The oxytocin receptor is a G-protein-coupled receptor that requires Mg2+ and cholesterol. It belongs to the rhodopsin-type (class I) group of G-protein-coupled receptors."  
Virtually all vertebrates have an oxytocin-like nonapeptide hormone that supports reproductive functions and a vasopressin-like nonapeptide hormone involved in water regulation."    
Maternal behavior: Female rats given oxytocin antagonists after giving birth do not exhibit typical maternal behavior.[65] By contrast, virgin female sheep show maternal behavior toward foreign lambs upon cerebrospinal fluid infusion of oxytocin, which they would not do otherwise.[66] Oxytocin is involved in the initiation of maternal behavior, not its maintenance; for example, it is higher in mothers after they interact with unfamiliar children rather than their own.[67]"  

    "Oxytocin is typically remembered for the effect it has on prosocial behaviors, such as its role in facilitating trust and attachment between individuals. Consequently, oxytocin is often referred to as the “love hormone".[97] However, oxytocin has a larger, and more complex role than solely enhancing prosocial behaviors."    
To make the role of oxytocin even more complex, it has been shown that oxytocin differentially affects males and females."    
Oxytocin increases defensive responding to unpredictable stimuli, but not to predictable stimuli. This result leads to the assumption that oxytocin’s effect is context-dependent. Thus, oxytocin may reinforce prosocial behaviors after an initial bond is formed, but may enhance defensive behaviors to unfamiliar individuals.[97]

    Oxytocin is beneficial because it can either enhance social bonding or promote defensive behaviors depending on the situation.[97] It would not be adaptive if oxytocin consistently enhanced social approach and other prosocial behaviors, especially in uncertain and potentially dangerous social contexts. Fear and anxiety are typically thought to be maladaptive, as these traits often underlie various psychological disorders. However, it is important to note that both fear and anxiety responses help to protect an individual. These emotions render environmental cues more important, leading to a greater likelihood the individual or animal will acknowledge the potential threat. Ultimately this process leads to a greater chance of survival."  

My comments
    My mother's Sociopathy makes me especially interested in the role of oxytocin in maternal behavior.

Searching PubMed for "oxytocin" yielded 22,054 references: 
Oxytocin - PubMed  

Searching PubMed for "oxytocin physiology" yielded 14,281 references: 

Searching PubMed for "oxytocin amphioxus" yielded just a single reference:
Characterization of the neurohypophysial hormone gene loci in elephant shark and the Japanese lamprey: origin of the vertebrate neurohypophysial hormone genes
    "Jawed vertebrates contain at least one homolog each of vasopressin and oxytocin, whereas only a vasopressin-family hormone, vasotocin, has been identified in jawless vertebrates."  
The amphioxus locus encodes a single neurohypophysial hormone, designated as [Ile4]vasotocin."  
    "Neurohypophysial hormones are an ancient family of structurally and functionally related nonapeptides, with representatives found in deuterostomes as well as in protostomes. Vasopressin and oxytocin are mammalian neurohypophysial hormones with distinct activities: vasopressin has renal urine reabsorption (antidiuretic) and blood-pressure raising (vasopressor) activities while oxytocin has uterus-contracting (uterotonic) and milk-ejecting (galactagogic) activities. "  
All jawed vertebrates contain at least one vasopressin-family, basic peptide and one oxytocin-family, neutral peptide whereas only a vasopressin-family peptide has so far been identified in jawless vertebrates such as lamprey and hagfishes [1,2]. Vasotocin is the vasopressin-family peptide in all non-mammalian vertebrates. Oxytocin-family peptides, however, exhibit a wide diversity."  
In placental mammals, the genes encoding vasopressin and oxytocin are closely linked in a tail-to-tail orientation. Nevertheless, the two genes are expressed in distinct magnocellular neurons of the supraoptic nuclei and paraventricular nuclei of the hypothalamus. In addition, vasopressin is expressed in the parvocellular neurons of the paraventricular nuclei and suprachiasmatic nuclei [3]."  
Neurohypophysial hormones are an ancient family of hormones with representatives found in diverse taxa among invertebrates and vertebrates. However, invertebrates contain either a vasopressin-family peptide or an oxytocin-family peptide (Table (Table3)3) but seldom both peptides."   

Searching Google for "oxytocin amphioxus" yielded 33,100 references:       

A neurochemical map of the developing amphioxus nervous system

by S Candiani - ‎2012 - ‎Cited by 1 - ‎Related articles

    See:  Amphioxus Nervous System  

from:  Predatory Behavior 

2015    4<7   
Oxytocin tempers calculated greed but not impulsive defense in predator-prey contests.     
Human cooperation and competition is modulated by oxytocin, a hypothalamic neuropeptide that functions as both hormone and neurotransmitter.  
    Oxytocin's functions can be captured in two explanatory yet largely contradictory frameworks: the fear-dampening (FD) hypothesis that oxytocin has anxiolytic effects and reduces fear-motivated action; and the social approach/avoidance (SAA) hypothesis that oxytocin increases cooperative approach and facilitates protection against aversive stimuli and threat. 
     We tested derivations from both frameworks in a novel predator-prey contest game. Healthy males given oxytocin or placebo invested as predator to win their prey's endowment, or as prey to protect their endowment against predation. Neural activity was registered using 3T-MRI.  
    In prey, (fear-motivated) investments were fast and conditioned on the amygdala. Inconsistent with FD, oxytocin did not modulate neural and behavioral responding in prey.  
    In predators, (greed-motivated) investments were slower, and conditioned on the superior frontal gyrus (SFG). Consistent with SAA, oxytocin reduced predator investment, time to decide and activation in SFG.  
    Thus, whereas oxytocin does not incapacitate the impulsive ability to protect and defend oneself, it lowers the greedy and more calculated appetite for coming out ahead.
   Free PMC Article   
Cumulating evidence from neurobiology and behavioral sciences suggests that human cooperation and competition is modulated by oxytocin, an evolutionary ancient neuropeptide that is produced in the human hypothalamus."  
The first perspective on the influence of oxytocin on human cooperation and competition rests on the fact that, on its hypothalamic release, oxytocin targets the regions of the spinal cord that regulate the parasympathetic branch of the autonomic nervous system.  Oxytocin interacts with the hypothalamic–pituitary–adrenal axis to attenuate stress responses: it reduces cortisol levels after exposure to stressors, inhibits cardiovascular stress responses and modulates neural circuitries involved in the processing of fear-related information. 
    Accordingly, participants receiving intranasal oxytocin (vs placebo) showed reduced activation of the amygdala and attenuated coupling of the amygdala to brainstem centers responsible for autonomic and behavioral components of fear when processing fearful faces , were less fearful of being exploited and more trusting of others. Together, these works converge on the fear-dampening (FD) hypothesis: oxytocin dampens activation in the amygdala and its direct and indirect role in fear-responding and thus enables humans to extend trust.
The alternative social approach/avoidance (SAA) perspective on the influence of oxytocin on human cooperation and competition rests on the well-established notion that human emotion and behavior are grounded in a tendency to approach positively valued and to avoid aversive negatively valued states. It accordingly proposes that oxytocin (i) promotes approach-related exploration rather than exploitation, including pro-social behavior such as cooperation, while (ii) allows to adaptively respond to aversive stimuli and threat by, for example, flight, seeking shelter or, if needed, lashing out to neutralize the threat." 

2016    26>508 
Chronic CNS oxytocin signaling preferentially induces fat loss in high-fat diet-fed rats by enhancing satiety responses and increasing lipid utiliz.. 

Oxytocin's inhibitory effect on food intake is stronger in obese than normal-weight men.

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