Pycnogenol Improves Learning Impairment and Memory Deficit in Senescence-Accelerated Mice

Summary: Senescence accelerated mice of the memory-impairment variety do better learning with pycnogenol.

Interestingness: 2

Paper by Fujun Liu, Yongxiang Zhang and Benjamin HS Lau in the Journal of Anti-Aging Medicine, Volume 2, Issue 4, Winter 1999.

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This is another one of those give substance to senescence accelerated mice (SAM) (see http://readingrejuvenationresearch.blogspot.com/2010/01/interventions-of-senescence-in-sam-mice.html), watch them act normal type papers. In this case, the substance, pycnogenol, was a commercial extract of the bark of the French maritime pine, which is made up mostly of procyanidins, which is the class of oligomers of flavonoids. The SAM chosen was SAMP8, which has mental issues. The task was learning. The SAMP8 did better when given the substance compared to controls, and about as well as the SAM resistant variety in these groups of 10 mice each. The suspected mechanism is anti-oxidant activity. Whoopee.

The interesting bit of the paper is the description of the memory experiments, which I'd heard mentioned before, as passive and active avoidance, but not described.

The passive avoidance tests are the if-you-move-I-shoot type, and they did two tests, called step-through and step-down. In the step-through test, mice are put in a bright area. There is a little tunnel to go to the dark area. Mice usually try to avoid being in a bright area, but when they go through the tunnel they get electrically shocked. If they don't go through on subsequent tests, it is assumed that they learnt. In the step-down test, they are put on a small rubber pad, surrounded by a sea of electric shock metallic mesh. If they stay on the pad for ten minutes, they "win".

The active avoidance test is, as expected, approximately the opposite. They are put in an area with two infrared beams that can be triggered. For ten seconds before the mesh below their feet becomes electrified, an alarm sounds and a light goes on, then the electricity is turned on for ten seconds. If they trigger both beams while the alarm is going on, either before or during the electric shock, the electricity is turned off. To trigger the beams they would have to run around.
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Abstract follows:

Pycnogenol (procyanidins extracted from the bark of French maritime pine, Pinus maritima Aiton) has been shown to be a potent free radical scavenger and an antioxidant phytochemical. The effects of pycnogenol on learning impairment and memory deficit in senescence-accelerated mouse (SAM) as a murine model of accelerated aging were determined. SAMP8, a strain of senescence-prone mice, exhibits immunodeficiency, hemopoietic dysfunction, learning impairment, and memory deficit. The effects of pycnogenol on learning performance and memory deficit were measured using step-through and step-down passive avoidance tests and shuttle box conditioned avoidance test. Oral feeding with pycnogenol for 2 months increased the retention rate in the step-through and the step-down tests and the rate of conditioned avoidance response in the shuttle box test. The latency of mice in the step-through test and the number of successful mice in the step-down test also increased with pycnogenol feeding. These results suggest that pycnogenol can improve learning impairment and memory deficit associated with aging.