Biosynthesis of Myo-Inositol by Rat Testis Following Surgically Induced Cryptorchidism or Treatment With Triethylenemelamine

Abstract

The biosynthesis of inositol from d-glucose was measured in testis slices from normal, cryptorchid and triethylenemelamine (TEM)-treated rats. A significant reduction of inositol synthetic activity accompanied the disappearance of spermatids and spermatozoa in both cryptorchid and TEM-treated animals. The onset of reduced inositol synthetic activity was extremely rapid in the cryptorchid testis, and preceded the appearance of grossly demonstrable histological alterations. These data suggest that de novo inositol synthesis might be required for maintenance of the cellular integrity of the germinal epithelium. This hypothesis is discussed in conjunction with recent theories concerning the r\l=o^\leof inositol in the uptake of protein and nucleic acid precursors.

The Nutritional Significance, Metabolism, and Function of myo-Inositol and Phosphatidylinositol in Health and Disease

“…Since the epididymis maintains a higher concentration of this cyclitol than the testis, Eisenberg and Bolden (1964) proposed that inositol may play a role in the maturation of spermatozoa as they migrate through the epididymis. Triethylenemelamine administration to rats or surgical cryptorchidism resulting in a decrease in inositol synthesis was concomitant with the disappearance of spermatids and spermatozoa (Morris and Collins, 1971), suggesting the involvement of inositol in spermatogenesis. Robinson and Fritz (1979) have suggested that inositol may be one of the components synthesized by Sertoli cells which are important in establishing the unique microenvironment in the seminiferous tubule required for germinal cell development.…”

Characterization of the Expression and Regulation of Genes Necessary for myo-Inositol Biosynthesis and Transport in the Seminiferous Epithelium1

“…Inositol-1-phosphate is then converted to myo-inositol by the phosphatase IMPA1 [12,15]. It has been well documented that both of these enzymes have high activity in the testis [12,14,16,17]. The testis is one of the only organs in the body that can produce myo-inositol de novo from glucose-6-phosphate [18] and it appears all of the myo-inositol within the testis is produced this way.…”

“…Most studies that examine myo-inositol in the testis have focused on the enzyme activity of ISYNA1 and IMPA1 [12,16,17] or the concentration of the molecule itself [1,2,4,6]. Our focus here was to investigate where these genes are expressed in the testis.…”