Center for Neural Science, New York University, New York, NY 10003, USA.
J Neurosci Methods. 2010 Aug 15;191(1):83-9. doi: 10.1016/j.jneumeth.2010.06.011. Epub 2010 Jun 17.
Standard methods for behavioral and neurophysiological experiments in the non-human primate rely on controlled water access as a means for motivating subject performance. It is, however, still not clear whether animals are able to regulate their fluid balance appropriately under these experimental settings. Further, the physical state associated with a subject monkey's thirst has not yet been objectively assessed under these conditions. Both of these deficiencies arise from the lack of a method for independently evaluating the hydration state of these subjects during experimental testing. To address these limitations, we measured the blood osmolality, the most widely used hematological index of hydration status, of three rhesus monkeys under conditions of controlled water access while they participated in a standard reinforced behavioral task for fluid rewards. We found that day-to-day hydration levels, as measured by serum osmolality, appears to be well regulated in a narrow range of values (300-320 mOsmo/kg H(2)O) by experimental subjects under these conditions: animals work harder and longer to earn more water rewards on a day when they are in a lower hydration state (higher osmolality) than when they are in a higher hydration state (lower osmolality). We also found that osmolality level decreases almost immediately after water intake, within 30 min, in a surprisingly linear manner. Osmolality thus seems to provide a fairly precise reflection of the monkeys' hydration state on a timescale of minutes. This evidence suggests that osmolality can be used as a tool for monitoring the hydration level of experimental subjects.
标准的非人类灵长类动物行为和神经生理学实验方法依赖于控制水的获取，作为激励实验动物表现的手段。然而，目前尚不清楚动物是否能够在这些实验环境下适当地调节它们的液体平衡。此外，在这些条件下，与实验猴子口渴相关的身体状态尚未被客观地评估。这两个缺陷都源于缺乏一种方法来独立评估这些实验动物在实验测试期间的水合状态。为了解决这些局限性，我们在三只恒河猴进行控制水获取的同时，参与了标准强化行为任务以获得液体奖励，测量了血液渗透压，这是水合状态的最广泛使用的血液学指标。我们发现，通过血清渗透压测量的日常水合水平似乎在一个狭窄的范围内（300-320 mOsmo/kg H2O）得到了很好的调节：在这些条件下，动物在较低水合状态（较高渗透压）下比在较高水合状态（较低渗透压）下工作更努力、更长时间以获得更多的水奖励。我们还发现，渗透压水平在饮水后几乎立即下降，以惊人的线性方式在 30 分钟内下降。因此，渗透压似乎在几分钟的时间尺度上提供了猴子水合状态的相当精确的反映。这一证据表明，渗透压可以作为监测实验动物水合水平的工具。
