Changes in the concentrations of LH and FSH testicular receptors have been studied in the pig, from neonatal to adult life, and correlated with blood LH, FSH and testosterone concentrations. Quantification of gonadotrophin receptors was performed in equilibrium binding studies, using homologous systems. The presence of high-affinity binding sites for LH and FSH (association constant (Ka): LH approximately 20 litres/nmol; FSH approximately 10 litres/nmol) was demonstrated in the testes of all animals studied. The apparent affinity of LH and FSH receptors did not change significantly with age. During the first weeks of life, there was a transient rise in LH receptor content, reaching a maximum of 8.7 +/- 2.2 (mean +/- S.E.M.) pmol/g testis at 24 days of age. This was correlated with a peak in testosterone secretion and reflects the second wave of interstitial cell proliferation in the pig. A second increase in the number of LH receptors occurred after 12 weeks of age and corresponds to pubertal maturation and final differentiation of adult Leydig cells. During this period, circulating concentrations of testosterone markedly increased without any significant variation in LH blood levels, suggesting a change in testicular sensitivity to LH in the maturing pig. A continuous increase in FSH receptor content was observed from the neonatal to the adult pig. This increase occurred in two phases. During the first 2 months of life, the increase in the number of FSH receptors exceeded that of testis growth rate and resulted in an increase in FSH receptor concentrations which reached a peak at 12.1 +/- 1.8 pmol/g testis, at week 9.(ABSTRACT TRUNCATED AT 250 WORDS)
Familial (hereditary) haemochromatosis (HH) is an iron storage disorder characterized by an increased intestinal absorption of iron and its accumulation in numerous tissues. The disease generates an iron overload with tissue damages also seen in haematologic disturbances (with dyserythropoiesis and haemolysis) and hepatic disorders. Besides typical mutations linked to HH (C282 Y and H63D, HFE locus), three other mutations have been identified and more have to be defined. A complete genetic testing is important to assess the risk of morbidity. Indeed, the clinical picture of HH is dependent upon the specific mutations as well as the individual context (sex, environment, associated hepatic and/or haematologic disorders). Porphyria cutanea tarda (PCT) has for long been found significantly associated with HH. It is now considered that hepatic iron overload related to the combination of heterogeneous genetic traits and environmental factors, including alcoholism and viral hepatitis, precipitates the expression of PCT through the inhibition of uroporphyrinogen decarboxylase (Uro.D).
