Testis Structure and Function in a Nongenetic Hyperadipose Rat Model at Prepubertal and Adult Ages

Abstract

There are few data for hormonal levels and testis structure and function during postnatal development in rats neonatally treated with monosodium L-glutamate (MSG). In our study, newborn male pups were ip injected with MSG (4 mg/g body weight) every 2 d up to 10 d of age and investigated at prepubertal and adult ages. Plasma levels of leptin, LH, FSH, prolactin, testosterone (T), corticosterone, and free T4 (FT4) were measured. MSG rats displayed elevated circulating levels of corticosterone and hyperadiposity/hyperleptinemia, regardless of the age examined; conversely, circulating prolactin levels were not affected. Moreover, prepubertal MSG rats revealed a significant (P < 0.05) reduction in testis weight and the number of Sertoli (SC) and Leydig cells per testis. Leptin plasma levels were severalfold higher (2.41 vs. 8.07; P < 0.05) in prepubertal MSG rats, and these animals displayed plasma LH, FSH, T, and FT4 levels significantly decreased (P < 0.05). Taken together, these data indicate that testis development, as well as SC and Leydig cell proliferation, were disturbed in prepubertal MSG rats. Adult MSG rats also displayed significantly higher leptin plasma levels (7.26 vs. 27.04; P < 0.05) and lower (P < 0.05) LH and FSH plasma levels. However, T and FT4 plasma levels were normal, and no apparent alterations were observed in testis structure of MSG rats. Only the number of SCs per testis was significantly (P < 0.05) reduced in the adult MSG rats. In conclusion, although early installed hyperadipose/hyperleptinemia phenotype was probably responsible for the reproductive axis damages in MSG animals, it remains to be investigated whether this condition is the main factor for hypothalamus-pituitary-gonadal axis dysfunction in MSG rats.

The sensitivity of male rat reproductive organs to monosodium glutamate

“…e quantitative comparison of the number of Leydig cells among MSG-rats and normal rats remains to be investigated. e present decreased epididymal sperm concentration in rats treated with a high dose MSG (6 g/kg body weight) is consistent with previous studies (9)(10)(11). In addition, our results further demonstrated decreases in the size and weight of the epididymis, some histological changes in the testes, and a depletion of plasma testosterone hormone in rats treated with a high dose of MSG.…”

“…França et al, (9) reported histological alterations of the testes in prepubertal 4 mg/kg body weight of MSG rats and found a significant reduction of spermatogenic cells (SCs) in the testes of adult MSG rats. eir nding of SCs is supported by our present nding that these SCs were sloughing into seminiferous tubule lumen (Fig 2c and 2d).…”

“…e plasma levels of gonadotropic hormones (FSH and LH) and testosterone, and the total number of Leydig cells have been reported to be signi cantly decreased in prepubertal rats treated with 4 mg/kg body weight of MSG (9). In adult male rats, it has been shown that administration of 4 g/kg body weight of MSG signi cantly decreased the plasma testosterone level (11).…”

“…ere have recently been several reports indicating that administration of MSG may a ect the sperm count in both neonatal and adult animals (8)(9)(10)(11) and the glutamate receptors and transporters are expressed in the testis and sperm of mice, rats, and humans (12,13). However, the roles of glutamate receptors present in male reproductive organs, including the sperm, have not been elucidated.…”

Sexual Maturation in Common Vole (<I>Microtus arvalis</I>) Males Raised under Laboratory Conditions

“…Production of this hormone takes place in testes (SOLOMON et al 2011). After conversion into dihydrotestosterone, testosterone controls secondary sexual trait development, accessory sex gland development and spermatogenesis (FRANÇA et al 2006). Sperm production and sperm maturation is also regulated by testosterone (RACHMAN & CHRISTIAN 2007;SUN et al 1990) and the number of sperm is an indicator of spermatogenesis effectiveness (RUIZ-PESINI et al 2000).…”