Laminar Analysis of the Number of Neurons, Astrocytes, Oligodendrocytes and Microglia in the Visual Cortex (Area 17) of 3-Month-Old Rhesus Monkeys Fed a Human Infant Soy-Protein Formula with or without Taurine Supplementation from Birth

Abstract

The effect of taurine addition to a commercial (taurine-free) soy-protein formula on the development of the visual cortex has been examined in 3-month-old rhesus monkeys. The thickness, number of neurons, astrocytes, oligodendrocytes and microglia have been measured in the different laminae. There were no significant differences in cortical thickness, total number of neurons, astrocytes, oligodendrocytes, or microglia between the groups, but there were some significant differences in some laminae as well as some qualitative differences. The numerical density of neurons in layers IV-Cα and V-2 was significantly greater in the taurine-supplemented monkeys than in those fed the taurine-free formula; the numerical density of astrocytes in layer IV-A was significantly greater and in layer IV-Ca was significantly smaller in the taurine-supplemented monkeys than in those fed the taurine-free formula. A number of other measurements in the two groups approached significance. These differences indicate that there are developmental disadvantages in the visual cortex of rhesus monkeys raised on a taurine-free human infant formula in addition to those previously reported.

Laminar Analysis of the Number of Neurons, Astrocytes, Oligodendrocytes and Microglia in the Visual Cortex (Area 17) of 6- and 12-Month Old Rhesus Monkeys Fed a Human Infant Soy-Protein Formula with or without Taurine Supplementation from Birth

“…The changes with age in total number of neurons and glia per square millimeter of visual cortex are depicted in figure 8, in cluding our previous data from 3-month-old monkeys [24], The number of neurons increased slightly (15%) from 3 to 6 months and then decreased considerably (59% in the + T group and 41% in the -T group), as expected with increased brain growth. As with their nu- 62 Palackal/Neuringer/Sturman Taurine Nuirltion and Quantitalivc Architectonics in Area 17 merical density, the total number of oligodendrocytes increased throughout development, as expected, since they continue to proliferate in the monkey brain postnatally.…”

“…The typical mammalian cortical layers described by Brodmann [30] and reported in our previous study [24] were similar in all diet groups at 6 and 12 m onths of age ( fig. 1-6).…”

“…1-6). The values for neurons at 6 and 12 months generally resemble those found at 3 months in distribution amongst the layers [24], with layer I being lowest and layer IV -Q being highest. However, some developmental changes can be noted, such as decreasing numerical densities of neurons between 6 and 12 months in all layers.…”

“…The brains were rapidly removed and preserved. The procedures of preservation, identification of brain regions, tissue sampling and various stages of morphometric analysis were performed as de scribed in detail in our previous report of results for the 3-monthold groups [24,28,29]. Briefly, Nissl, toluidine blue, Bodian and rapid Golgi sections were used to compare the laminar organiza tion of the primary visual cortex.…”

“…We have previously reported that such infants fed formula alone for 3 months had reduced plasma and tissue taurine concentrations [19], reduced proportions of taurine-conjugated bile acids [19], impaired visual acuity [20,21], and degenerative changes in retinal photoreceptors, particularly cones in the foveal region [21,22], These animals also showed qualitative and quantitative alterations in the visual cor tex, including impaired neuronal differentiation and ar borization, and small, but significant, changes in the laminar distribution of neurons and glia [23,24], We have now extended these studies to include infant m on keys raised for 6 and 12 months on the same dietary regimens. Tissue taurine concentrations and the propor tion of bile acids conjugated with taurine were reduced in the 6-month-old monkeys fed form ula alone but in the 12-month-old monkeys these parameters were not signif icantly different between the deprived and supplemented groups [25,26].…”