Prenatal sex steroid exposure plays an important role in determining child development. Yet, measurement of prenatal hormonal exposure has been limited by the paucity of newborn/infant data and the invasiveness of fetal hormonal sampling. Here we provide descriptive data from the MIREC-ID study (n=173 girls; 162 boys) on a range of minimally invasive physical indices thought to reflect prenatal exposure to androgens [anogenital distances (AGDs); penile length/width, scrotal/vulvar pigmentation], to estrogens [vaginal maturation index (VMI) – the degree of maturation of vaginal wall cells] or to both androgens/estrogens [2nd-to-4th digit ratio (2D:4D); areolar pigmentation, triceps/sub-scapular skinfold thickness, arm circumference]. VMI was found to be associated with triceps skinfold thickness (β=0.265, P=0.005), suggesting that this marker may be sensitive to estrogen levels produced by adipose tissue in girls. Both estrogenic and androgenic markers (VMI: β=0.338, P=0.031; 2D:4D – right: β=−0.207, P=0.040; left: β=−0.276, P=0.006; AGD-fourchette − β=0.253, P=0.036) were associated with areolar pigmentation in girls, supporting a role for the latter as an index of both androgen and estrogen exposure. We also found AGD-penis (distance from the anus to the penis) to be associated with scrotal pigmentation (β=0.290, P=0.048), as well as right arm circumference (β=0.462, P<0.0001), supporting the notion that these indices may be used together as markers of androgen exposure in boys. In sum, these findings support the use of several physical indices at birth to convey a more comprehensive picture of prenatal exposure to sex hormones.

There is strong evidence that the gonads modulate the hypothalamic–pituitary–adrenal axis. To investigate these sex differences at the adrenal glands of sheep we compared the cortisol response to ACTH (experiment 1) and measured the relative expression of oestrogen receptor alpha (ERS1), androgen receptor (AR), melanocortin 2 receptor (MC2R) and steroid acute regulatory protein (STAR) mRNA in adrenal glands (experiment 2) of gonadectomised rams and ewes either with or without sex steroid replacement. In experiment 1 six castrated adult rams and four ovariectomised adult ewes were used in two ACTH trials. On each trial blood samples were taken every 15 min for 4 h through an indwelling jugular catheter and each animal received 0.5 mg of an ACTH analogue i.v., immediately after the sample at 1 h from the beginning of the trial. Four days after the first trial the males received 100 mg of Testosterone Cyclopentilpropionate (TC) i.m. and the females received 2.5 mg of Oestradiol Benzoate (EB) i.m. At 72 h after TC or EB administration the second trial was performed. In experiment 2 the adrenal glands were obtained from gonadectomised adult rams (n=8) and adult ewes (n=8). Four rams received 100 mg of TC i.m. and four females received 0.5 mg of EB i.m. Blood samples were taken at 0, 12, 24, 48 and 72 h relative to steroid replacement and the animals were thereafter slaughtered. Cortisol, testosterone and 17β-oestradiol were determined by radioimmunoanalysis. The transcripts of ERS1, AR, MC2R and STAR were determined by real-time reverse transcription PCR in adrenal tissue. Cortisol secretion was higher in female sheep than in male sheep, and higher in EB-treated than non-treated ewes. No difference in cortisol secretion was observed between TC-treated and non-treated rams. Gonadectomised rams treated with TC presented greater AR mRNA and MC2R mRNA expression than males without the steroid replacement. Gonadectomised ewes treated with EB tended to present lower AR mRNA than the ones without steroid replacement. Gonadectomised rams with TC also had greater AR mRNA, ERS1 mRNA and MC2R mRNA expression than ewes treated with EB. The relative amount of STAR transcript was not different among the different groups. The results confirm sex differences in ACTH-induced cortisol secretion in sheep, as well as in the expression of the receptor proteins for both 17β-oestradiol and testosterone in the sheep adrenal gland. However, the underlying mechanisms for sex steroid modulation remain unresolved.

Reproductive parameters of Ligula intestinalis-infected roach (Rutilus rutilus) which were held under long-tem laboratory conditions with unlimited food supply were investigated. Although uninfected and infected roach showed no difference in condition factor and both groups deposited perivisceral fat, the gonadosomatic-index was significantly lower in infected female and male roach. Quantitative histological analysis revealed that gonad development was retarded upon parasitization in both genders. In contrast to the phenotype described in the field, infected females were able to recruit follicles into secondary growth, but a high percentage of secondary growth follicles underwent atresia. In both genders, the histological data corresponded well with reduced expression of pituitary gonadotropins and lowered plasma concentrations of sex steroids, as revealed by real-time RT-PCR and ELISA, respectively. Furthermore, a reduction of vitellogenin mRNA and modulated expression of sex steroid receptors in the liver was demonstrated. Like in the field, there was a significant adverse impact of L. intestinalis on host reproductive physiology which could not be related to parasite burden. Our results show, for the first time, that maintenance under laboratory conditions can not abolish the deleterious effect of L. intestinalis on gametogenesis in roach, and indicate a specific inhibition of host reproduction by endocrine disruption.

The effects of parasite infection by the cestode Ligula intestinalis on the reproductive function and endocrine system of wild roach Rutilus rutilus were evaluated. Gonad maturation, plasma vitellogenin, plasma steroid concentrations (i.e. progesterone, 11-keto-testosterone and 17-β-estradiol) and brain aromatase activity were investigated in relation with parasitization. A low prevalence (8%) of ligulosed roach and a moderate impact of parasitization (mean parasitization index of 8·8%) were found in the studied population. Inhibition of gonad maturation generally resulted from infestation but 5% of the ligulosed roach nevertheless reached maturity. Main sex steroid plasma content was depleted in both genders. Male 11-keto-testosterone, female 17-β-estradiol and progesterone plasma concentrations of both genders were, respectively, 27, 5 and 3 times lower in ligulosed fish when compared to their non-infected counterparts. Progesterone levels were negatively correlated with the parasitization index in females. Brain aromatase activity of infected roach was reduced to 50% of that of the non-infected fish. These results demonstrate significant negative effects on the reproductive function of wild roach infected by the tapeworm L. intestinalis collected from a site with low contamination.

Sex steroids play a significant role in regulating the parasite load in experimental intraperitoneal Taenia crassiceps cysticercosis of male and female Balbc/anN mice. Briefly, oestrogens increase parasite loads and androgens decrease them (1) by acting directly on the parasite, favouring or hindering its reproduction, respectively, and (2) by biasing the hosts' immune response towards a parasite-permissive Th2 or a parasite-restrictive Th1 response. The infected male host also undergoes drastic endocrinological and behavioural changes that may impinge upon the course of infection, and the host's mating behaviour and its exposure to predators. In addition, at different times of infection, significant changes occur in the expression of c-fos in the host's hyppocampus, hypothalamus and preoptic area. Thus, the host's brain seems to sense and/or react to intraperitoneal infection. The physiological domains of the network affected by the infection, which classically included the hypothalamus-pituitary-axis and the immune system, must now incorporate the host's sexual hormones and other areas of the brain. The network's complex circuitry and functions may help understand some basic questions of parasitology (i.e. the hosts' sexual dimorphism in parasite infections, host-parasite specificity, heterogeneity in the course and outcome of infections at different stages of parasite and host development). The plurality of elements and the complexity of the network that regulates the host-parasite relationship also point to additional strategies for the treatment and control of infections.

Sex steroid levels were determined in various commercial fish meals and complete diets. The results obtained demonstrate that estrone (E1), 17 β-estradiol (E2) and androgens (A) (testosterone and 11-ketotestosterone), are present in diets in high quantities (up to 935±350 ng/100 g for E2, 615±190 ng/100 g for E1 and 1100±120 ng/100 g for A) and with considerable variation both between different diets, and between different batches of the same diet. These high levels of sex steroids are thought to influence the sex steroid plasmatic levels and plasma vitellogenin content in fish. Plasma sex steroid assays in the Siberian sturgeon Acipenser baeri show that plasmatic 17 β-estradiol levels are never significantly different between males and females at various stages of oogenesis and spermatogenesis, except in 6 year old females in stage IV, which corresponds to the maximum incorporation of vitellogenin. In males the plasma 17 β-estradiol levels are exceptionally high and induce vitellogenin synthesis, as demonstrated by various chemical and immunological techniques.