6. What is the passage mainly about?
(A)People can medicate their depression with sugar.
(B)Baby mice suffered so much from isolation that they should be given some sweet food to relieve their pain.
(C)The soothing effect of sugar is not just something psychological but has a lot to do with an actual chemical reaction.
(D)The result of the mice experiment suggests that people should take more sweet substances to cope with depression.

Animal studies confirm that the relief some of us get from eating sugar is not just psychological—it is an actual brain-chemistry reaction. In one experiment, Blass and colleagues studied two groups of baby mice who were separated單獨的，不同的, （使）分離 from their mothers and left alone for six minutes. Their resulting 因而發生的；作為結果“isolation distress憂慮；悲傷；痛苦” was considered to be a kind of animal equivalent等值的；相等 to our human version of depression憂鬱，抑鬱；消沉.

The depressed mice who were given sugar water cried only seventy-five times during their isolation—as compared to the more than three hundred cries that came from the mice left alone with no sweet treat to alleviate減輕；緩和 their emotional pain. Apparently據…, the young mice were literally確實 “medicating 用藥醫治” their depression with sugar. 

        Why did sugar have this remarkable effect? Researchers thought that perhaps the sweet food stimulated激發，激勵 the release of extra beta-endorphin腦內嗎啡 molecules分子. Since these molecules分子 help us cope with physical and emotional pain, the sugar had a literally確實 soothing平靜, 安慰 effect. Researchers confirmed their theory by giving both groups of mice Naltrexone納曲酮, a drug that blocks beta-endorphin腦內嗎啡 receptors受器. If you take Naltrexone納曲酮, it does not matter how many beta-endorphin腦內嗎啡 you release—you will not get any relief from pain. Sure enough果然，果真, when the sugar-fed mice were given Naltrexone納曲酮, they lost all interest in the sweet substance材料, 物質, suggesting提及, 提議；建議 that their only reason for their sweet tooth had been to stimulate激發，激勵 the release of beta-endorphin腦內嗎啡. 

        Numbed（身體部位）麻木的，失去感覺 by Naltrexone納曲酮, both groups of mice cried equally often. The poor baby mice were still depressed引起憂鬱—but now even sugar could not make them feel better.