What causes short-term dysphoria following intense pleasure? I'm interested in the phenomenon of short term Dysphoria:


  Dysphoria is a state of feeling unwell or unhappy; a feeling of emotional and mental discomfort as a symptom of discontentment, restlessness, dissatisfaction, malaise, depression or anxiety.


What interests me is when Dysphoria arises following moments of intense pleasure:


Post-coital tristesse, a feeling of blues following orgasm
Postorgasmic illness syndrome
Dysphoria associated with recreational drug use, where X minutes of euphoria are followed by Y minutes of dysphoria ( I do not know the term for this one).


The phenomenon that I'm describing lasts from 5 minutes to a few hours, then disappears. It is experienced by only a small subset of population.

I tried to look for an explanation, but cannot find the cause - why Dysphoria appears following intense pleasure? Is Dopamine or Dopamine Transporter or D2 receptors involved in some way ? Is this some sort of sensitization/desensitization homeostasis mechanism at play?

Thank you for any search terms or hints that would help me shed light on the subject.
Dysphoria following drug use

Though their acting mechanisms can be vastly different, the general basis of drug addiction is its influence on the reward system, particularly through dopamine pathways[1].  It's thought that the stimulation of the dopamine system leads to dopamine depletion[2] and without dopamine, there's no rewarding behavior and thus no motivation to behave in any particular way (i.e. depression/dysphoria).

Desensitization occurs as a flooded dopamine body tries to reduce its receptor count, thus lowering its sensitivity to dopamine.  But since the dopamine stimulus was artificial (drug-induced) and not environmental, it will require more drugs to achieve a normal level again (i.e. "chase and drag").  And this is the basis for addiction.

Dysphoria following orgasm

I can not find any peer-reviewed information about the neurobiology of post-coital blues.  There are lots of MDs and professional psychologists that weigh in speculatively, but the literature is skimpy.  A speculation I've seen is, given that the coitus was genuinely with romantic partners (and thus not a social response), that its a biological dysfunction in the Amygdala as the amygdala sharply reduces activity after sex, but this response may be exaggerated in some individuals[3].  

My own speculation is that it might also be a way to promote promiscuity in the human race, evolutionarily speaking.  In modern day, it may not be as prevalent as infant mortality rates are much lower and monogamous relationships don't threaten human survival rates.

References

[1]Wise RA, Rompre PP, (1989). Brain dopamine and reward.  Annu Rev Psychol. 40:191-225.

[2]Charles A. Dackis, Mark S. Gold (1985).  New concepts in cocaine addiction: The dopamine depletion hypothesis. Neuroscience &amp; Biobehavioral Reviews, 9:3, 469–477

[3]Sex and depression: In the brain, if not the mind