The relationship between thyroid function and testicular development in the rat was investigated. Hypothyroidism was induced during fetal or post-natal life by adding methimazole (MMI) to the drinking water of pregnant or lactating mothers. A group of newborn rats was treated with MMI and i.p. injections of L-tri-iodothyronine (L-T3). Hypothyroidism was shown by the reduced serum levels of total T3 and of total thyroxine (T4) in pregnant mothers and in pubertal rats. Testes were studied using light microscopy at 18 and 21 days post coitum or during puberty (21, 35 and 50 days after birth); serum levels of gonadotrophins were also evaluated in pubertal rats. Hypothyroidism had no effect on testicular development during fetal life and when induced in newborn rats it was associated at puberty with reduced serum levels of FSH and LH and with delayed maturation of the testis compared with control rats. The delay in maturation consisted of a reduction in the diameter of seminiferous tubules, and a reduction in the number of germ cells per tubule; this was associated with increased degeneration and arrested maturation of germ cells. In addition, Sertoli cells demonstrated retarded development, as indicated by a delay in the appearance of cytoplasmic lipids and in the development of a tubule lumen. Hormonal and morphological abnormalities were absent in rats treated with MMI plus L-T3. In conclusion, hypothyroidism occurring soon after birth caused reduced levels of gonadotrophins in the serum and a delay in pubertal spermatogenesis, possibly due to retarded differentiation of the Sertoli cells.

Transforming growth factor-beta (TGFbeta) is a cytokine with autocrine and paracrine action in the testis and potent immunoregulatory and anti-inflammatory activities. In the present study, we examined the concentration of latent (acid-activatable) and free (active) TGFbeta in seminal plasma from normal subjects (n = 23) and infertile (n = 40) patients, by using a TGFbeta specific immunoenzymological assay, and a bioassay (CCL64 cell line growth inhibition) detecting any form of TGFbeta. Free TGFbeta1 was present in normal subjects at a concentration (1.82 +/- 1.06 ng/ml) close to that known to give maximal stimulation in vitro. In pathological groups, the mean concentrations were not significantly different from the normal ones. Latent TGFbeta1 was present in normal seminal plasma at a high concentration (92.4 +/- 29.2 ng/ml). In subjects with pathologies of both testis and genital apparatus, or with epididymal occlusion, mean latent TGFbeta1 concentrations were normal, whereas transferrin concentrations were lower. The concentrations found in the epididymal occlusion group indicate that TGFbeta1 is, for a large part, secreted by the genital tract. In the testicular pathology group, TGFbeta1 concentrations were 130.7 +/- 61.2 ng/ml, a mean not statistically different from normal, although higher. No differences were found between patients with high and normal blood plasma follicle stimulating hormone, and this is consistent with the notion that most TGFbeta1 in seminal plasma is not of testicular origin. The TGFbeta bioassay ensured that immunologically detected TGFbeta was present in a bioactive or bioactivatable form. Furthermore, the values found in normal and pathological seminal plasmas were usually higher than those detected by the immunoassay, suggesting that other forms of TGFbeta might be present. Together, the present data show that very large amounts of TGFbeta are present in human seminal plasma. The TGFbeta ligand assay in the seminal plasma appears to indicate no differences between normal and infertile subjects.

Total cortisol as well as percentage and absolute free cortisol values were determined in 75 full-term, 88 premature and 38 small-for-age (born at term) infants in the first 3 months of life. Equilibrium dialysis and radioimmunoassay were used to estimate the percentage value of the unbound fraction and the value of total cortisol from which absolute free cortisol level was calculated, respectively. A systematic decrease in the free cortisol value was observed in all the three groups of infants during the study period (in full-term infants from 32.3 to 19%, in prematures from 36.6 to 20.8%, and in small-for-age infants from 32.3 to 19.2%). A comparison between the percentage values of free cortisol in the groups studied revealed only slight differences which were not significant. The absolute free cortisol values in full-term infants were highest immediately after birth (4.05 μg/dl), then they fell to the lowest level of 0.67 μg/dl observed between the third and fifth days of life, and increased afterwards reaching the level of 1.89 μg/dl in the third month. The absolute free cortisol values in premature newborns at 3–5 days of life exceeded the values observed in full-term subjects. The pattern of free cortisol in the prematures seems to be ‘delayed’ as compared with that in full-term newborns. The absolute free cortisol values in small-for-age infants were much more similar to those found in the full-term subjects, than to those in premature babies.

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