Abstract: The effect of maternal alcohol consumption during pregnancy and lactation on the spermatogenesis in male offspring was studied in neonatal mice. Three groups of mice comprising 12 female and 3 male mice group were used. The offspring of group 1 served as control while those of groups 2 and 3 were exposed to 30% ethanol (V/V) prenatally and pre-and postnatally, respectively. At 6 weeks of age 10 male offspring were randomly selected from the three groups and sacrificed. Following sacrifice, the testes and cauda epididymis were carefully dissected out, fixed in Bouin`s fluid and prepared for routine histological examination. Examination of the seminiferous tubules showed delay in the development of spermatogenic cells as evidenced by few to no spermatozoa in the cauda epididymis of the alcohol-exposed groups.
INTRODUCTION
Alcohol ingestion by mothers during pregnancy can result to fetal alcohol syndrome (Jones and Smith, 1973). In experimental animal models, the syndrome is characterized by retardation of growth during fetal and neonatal life (Abel and Greizerstein, 1979; Lee and Leichter, 1980). Damage to the central nervous system (CNS) of the offspring has emerged as one of the most serious consequences of maternal alcohol consumption (Streissguth et al., 1986).
Human and non-human primate studies on brain structure and function now strongly suggest that consumption of alcohol during pregnancy can affect fetal brain structure and function (Clarren et al., 1985). Since fetal brain structure and function could be affected, the hypothalamic-pituitary-testicular axis regulation could be disrupted thereby leading to impairment in the synthesis and release of gonadotropins. The gonadotropins maintain the growth and maturation of testes in prepubertal mammals as well as the maturation and action of gonads (Grober et al., 1998).
The effect of maternal alcohol consumption on the growth and development of some parts of the body in both human and experimental animals have been documented (Lee and Leichter, 1980 ; Clarren et al., 1985; Ihemelandu, 1984; Nwaogu and Ihemelandu, 1999a, b; Onu and Ezeasor, 2001; Onu et al., 2002 a, b, c,d). The possible effect of alcohol consumed during pregnancy and lactation on spermatogenesis in the offspring has not been studied, hence this study.
MATERIALS AND METHODS
Experimental animals: The method employed in producing experimental fetal alcohol syndrome in this study is similar to that of Lee and Leichter (1980). 36 virgin female and 9 immature male mice were used in this study. They were randomly selected at the weaning age of 21 days from a colony of locally in-bred mice maintained for research in the Animal House of the Faculty of Veterinary Medicine, University of Nigeria, Nsukka. The virgin female mice were divided into three groups of 12 each while the immature males were kept separately. The three female groups and the immature males were housed separately in cages with screened tops and were acclimatized for 3 weeks before the commencement of the study.
At the beginning of the 7th week of age, the mice in groups 2 and 3 were given 10% ethanol (V/V) in drinking water for 2 weeks and 20% ethanol (V/V) for another 3 weeks. The three groups were then bred overnight by introducing one male mouse into a cage containing 4 females. Day 1 of pregnancy was presumed after observation of vaginal plug the following morning. Following diagnosis of pregnancy, the alcohol-exposed groups, 2 and 3 received 30% ethanol (V/V) till delivery. After delivery, the alcohol for group 2 (prenatal alcohol- exposed) was replaced with water while group 3 (pre-and postnatal alcohol-exposed) continued to receive 30% ethanol (V/V) till weaning their offspring at 21 days of age. At the sixth week of age which is the age of sexual maturity in male mice (Hafez, 1970) 10 male offspring were randomly selected from groups 1, 2 and 3 and sacrificed.
Histology: After sacrifice, the paired testes and cauda epididymis were dissected out and fixed in Bouin’s fluid. Thereafter, the tissues were processed in the normal paraffin procedure (Humason, 1979). The epithelium of the seminiferous tubules of the testes and the content of the lumina of the cauda epididymis were examined microscopically and described.
RESULTS
At the sixth week of age, the control testes contained a full spectrum of spermatogenesis. Regnaud body in the lumina of the tubules indicated that spermatozoa had been produced (Fig. 1). Profiles of seminiferous tubules of the prenatal alcohol-exposed testes had lumina but did not contain full spectrum of spermatogenesis. However, some profiles had few round and elongated spermatids (Fig. 2). In the pre-and postnatal alcohol-exposed testes, profiles of seminiferous tubules contained both early and late stages of primary spermatocytes apart from few round spermatids. There was no Regnaud body in the lumina of tubules of the two-alcohol-exposed groups. The lumina of cauda epididymis of the control mice were filled with spermatozoa (Fig. 3) while there was non in the lumina of cauda epididymis of the pre-and postnatal alcohol-exposed testes (Fig. 4).
DISCUSSION
The results of this study have demonstrated that maternal consumption of alcohol during pregnancy and lactation produces retardation of spermatogenesis in the male offspring. This is evidenced by the lack of full spectrum of spermatogenesis in the testes of the two alcohol-exposed groups. This is further highlighted by the sparsity of spermatozoa and none at al in the lumina of cauda epididymis of prenatal and pre-and postnatal alcohol-exposed groups respectively. This could be as a result of retardation of testicular growth in fetal alcohol syndrome as observed by Onu and Ezeasor (2001) and Onu et al. (2002a,b,c).
The mechanism by which alcohol consumed during pregnancy and lactation retarded spermatogenesis in the offspring was not established from the result of this study. However, alcohol being a neurotoxin (Leonard, 1989) could destroy the developing neurons including possibly those of the hypothalamus.
| Fig. 1 and 2: | Light micrographs showing cross sections of 6-week old testes of mice x 600 |
| Fig. 1: | Control, |
| Fig. 2: | Prenatal alcohol B exposed |
| Rs = round spermatidE = elongated spermatid | |
This could lead to disruption of hypothalamic-pituitary-testicular axis regulation and subsequent impairment of gonadotropin release. Taylor (1984) observed that alcohol impairs the fetal hormonal system. Courot et al. (1970) observed that spermatogenic division are under endocrine control. Leydig cells produce testosterone, which act on Sertoli cells to drive spermatogenesis. Although the precise mechanism by which this occurs is actually unknown, the requirement for testosterone is absolute (Sharpe, 1984). Steinberger et al. (1973) postulated that follicicle stimulating hormone (FSH) is essential for the later stages of spermatogenesis because in the absence of the hormone, maturation of seminiferous epithelium do not progress beyond the spermatid stage.
| Figs.3 and 4: | Light micrographs showing cross sections of 6-week old cauda epididymis x 600 |
| S = | spermatozoa in the lumina of the cauda epididymis of the control mice |
| L = | lumina of cauda epididymis of the pre-and postnatal alcohol-exposed mice without spermatozoa |
In this study, the seminiferous epithelium did not progress beyond the spermatid stage in the two alcohol-exposed groups. Therefore, the retardation of spermatogenesis in this study could be due to impairment of fetal hormonal system Taylor (1984), consequent upon disruption of the hypothalamic-pituitary-testicular axis regulation.
ACKNOWLEDGMENT
The authors are thankful to the authorities of Usmanu Danfodiyo University, Sokoto, for sponsoring this research work. The assistance rendered by Messrs. V. Dim and P. Aloka in the histotechnique section in the Department of Veterinary Anatomy, University of Nigeria, Nsukka, is appreciated.