COMMENTS: One of the few studies that covers how abstinence affects the levels of dopamine receptors.
Highlights:
– D2 receptors bounce back fairly quickly – less than a month
– D1 receptors are way too high at a month, but bounce back within 90 days.
– High or low D1 receptors may be keys to acute withdrawal and cravings
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COMMENTS: First study to show that drug use causes a decline in dopamine (D2) receptors. Important because addicts have a low number of such receptors, which may contribute to addiction. Also shows that receptors can bounce back, but maybe not in everyone.
LAY ARTICLE: Cocaine Abuse And Receptor Levels: PET Imaging Confirms Link
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Read More… from Addiction and Dopamine (D2) Receptor Levels (2006)
Scientists have actually measured many separate factors and their relationship to prostate cancer: 
ejaculation, intercourse frequency, marital status, number of sex partners, and cases of sexually transmitted disease. So far, study results conflict with each other on almost every factor, and the medical profession does not consider ejaculation frequency (or infrequency) to be risk factor for prostate cancer.
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Food on the Brain
Daniel Fisher, 01/10/05
Are the high-fat, sugar-laden things we crave addictive? Here’s what the latest scientific research is telling us.
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Read More… from (L) Are the high-fat, sugar-laden things we crave addictive? (2005)
Comment: Study demonstrates in humans that food – a natural reinforcer – can cause a decline in dopamine receptors. Is Internet porn less stimulating than “highly palatable” food? 
Released: 9/29/2010 4:30 PM EDT
Source: University of Texas at Austin
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Food Addiction: Could It Explain Why 70 Percent of Americans Are Fat?
Mark Hyman MD, October 16, 2010
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Read More… from (L) Food Addiction: Could It Explain Why 70 Percent of Americans Are Fat? (2010)
Comment: This study demonstrates that when an animal is given unlimited access, a strong natural reinforcer (very stimulating food) can cause a decline in D2 receptors. This decline was seen in nearly all rats, and occurred quite rapidly. When “highly palatable” food was removed, the rats refused to eat normal chow. The rats continued to […]
Targeting Gene Regulator in Brain Reward Circuit Eyed as Treatment
Scientists have discovered a mechanism that helps to explain resilience to stress, vulnerability to depression and how antidepressants work. The new findings, in the reward circuit of mouse and human brains, have spurred a high tech dragnet for compounds that boost the action of a key gene regulator there, called deltaFosB.
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Read More… from (L) Delta-FosB Low in Depression, Protects Mice From Stress (2010)
Comments: The rats preferred the intense sweetness of both sugar and saccharine over cocaine. This preference continued even when the dose of cocaine was increased, and when the rats had to work harder to receive their sweet reward. The take away is that the rats preferred a natural reinforcer (sugar) over an addictive drug. Internet […]
Read More… from Intense Sweetness Surpasses Cocaine Reward (2007)
This covers a lot of the basics on dopamine (D2) receptors and addiction.
Volkow May Have Uncovered Answer to Addiction Riddle
Psychiatric News June 4, 2004
Volume 39 Number 11 Page 32
Jim Rosack
http://pn.psychiatryonline.org/content/39/11/32.full
Addictive disorders may be a “shift in the salience meter” in which normal stimuli are no longer recognized as salient, yet the effects of drugs of abuse on the brain’s dopamine system are highly salient, NIDA’s director believes.
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Read More… from (L) Volkow May Have Uncovered Answer to Addiction Riddle (2004)