Effects of schistosoma mansoni infection on some reproductve parameters in rabbits

Abstract

Schistosomiasis is a major public health problem III tropical and subtropical countries. An estimated 200 million people are infected and 600 million are at risk of infection. In this study, the effect of S. mansoni on bioactive luteinizing hormone (LH), plasma levels of testosterone, histology of testes, epididymides and livers in the rabbit model were investigated. Male Newzealand rabbits were divided into four groups; Group I and III had 5 animals each, while group II and IV had 6 animals each. Animals in Group I, II, and III were exposed to 1000, 100 and 1000 S. mansoni cercariae respectively, while the fourth group remained as un'infected controls. Five weeks after infection, ft ' animals in Group III were treated orally with praziquantel (PZQ) at dose rate of 1000 mg/Kg body weight. Blood samples from the lateral ear vein were collected at 20 minute intervals for 4 hours on day 14 before infection (day -14) and also on days 14,42 and 70 after infection. S. mansoni infection significantly decreased the pulse frequence (P<0.05), amplitude (P< 0.05), area under LH curve (P<0.05) and mean plasma bioactive LH concentration (P<0.05) on day 42 and 70 in Group I and Group II animals. Pulsatility pattern ofLH was observed in control rabbits ( Group IV ) on the entire period. Area under the response curve for plasma testosterone levels decreased significantly (P<0.05) by day 42 post infection in Group I and Group II animals compared to day -14 values. In rabbits which were infected with 1000 or 100 cercariae, young round spermatids with pathological condensed nuclei were observed. There was also a reduction in the epithelial thickness and depletion of mature spermatozoa. Cauda epididymides of infected animals showed increased population of inflammtory cells. In the liver, the major lesions included periportal fibrosis, lymphocytic infiltration, blood vessels and bile duct proliferation. Early treatment with praziquantel inhibited endocrine changes but hepatic fibrosis was still observed. However, rectal temperature remained within normal range (38.2-39.S0C) in the course of the experiment and haematological parameters (i.e. PCV, Hb, and RBC) showed no significance difference (P>O.OS) between the infected and control animals. It is concluded that, the observed reproductive endocrine changes was due to a pituitary or hypothalamic hypofunction, and a lack of LH may playa role in the pathological transformation of the testicular tissue