Oestrogen receptors were measured in the cytosolic and purified nuclear fractions of rat liver. Both cytosolic and nuclear receptors bind oestrogen with high affinity (Kd = 1.47 and 2.28 nM respectively) and specificity similar to that of receptors in order oestrogen-target tissues such as the uterus. During the 4-day oestrous cycle the receptor content and distribution between cytosol and nucleus did not vary; in particular, the content of nuclear receptor did not appear to fluctuate in concert with known cyclic changes in the concentration of plasma oestrogen. Injection of 50 micrograms of oestradiol-17 beta or 10 micrograms of ethynyloestradiol resulted in a 4--6-fold increase in the nuclear receptor content, with a concomitant decrease in the unoccupied-receptor content of cytosol 1 h after injection. The nuclear receptors present after injection bind oestrogens with similar affinity (Kd = 2.78 nM) and specificity to receptors present in uninjected animals. The administration of lower doses of either oestrogen was less effective in producing increases in nuclear receptor content. Hence there is apparently substantial translocation of receptor to the nucleus in response to hyperphysiological doses of oestrogen, but not to the physiological changes in plasma oestrogen concentrations during the oestrous cycle. The response to exogenous oestrogens is discussed in relation to the clinical use of synthetic oestrogens and progestogens.

The administration of oestradiol-17 beta or ethynyloestradiol as well as the synthetic progestogen norethisterone acetate resulted in translocation of the oestrogen receptor. Progesterone and the synthetic progestogen (+)-norgestrel were ineffective. The increases in nuclear oestrogen receptor content 1 h after injection of each steroid were similar but different subsequently. The increase with oestradiol-17 beta extended for 3--6 h and for at least 9 h with ethynyloestradiol. With norethisterone acetate, nuclear content was still increased after 24 h. Oestrogen injection resulted in cytosol receptor depletion and a 'deficit' in receptor content extending for 6 h, whereas norethisterone acetate-induced translocation was quantitative. With injections of norethisterone acetate + ethynyloestradiol the increase at 1 h and retention of the nuclear receptors were similar to that with norethisterone acetate alone. In contrast, the depletion of cytosol receptor and its restoration were similar to that seen with ethynyloestradiol alone, suggesting that norethisterone acetate did not interfere with the oestrogen receptor replenishment. Specific binding in vitro of [3H]oestradiol-17 beta in liver cytosols was inhibited by (+)-norgestrel and norethisterone acetate, but not progesterone, at concentrations of 10--100 microM. Nuclear receptors present after norethisterone acetate injection bound oestrogen with high affinity (Kd = 1.52 nM), similar to receptors of oestrogen-injected animals. In the uterus, differential retention of nuclear receptors in response to oestrogens is associated with different cellular responses. The differences in the response of the receptor system in liver to the various steroids suggests that the corresponding tissue responses may also be dissimilar. These results are discussed in relation to the problems of liver dysfunction in oral-contraceptive users.

Muscle biopsies from two cases of polyarteritis nodosa (PN) and one of arteritis in assoication with rheumatoid arthritis (RA) were examined by electron microscopy. The histological changes were similar in all three cases. The endothelial cells of the small blood vessels were often hypertrophied. Inflammatory reaction was present mainly in the vicinity of the blood vessels. Individual muscle fibres showed mostly nonspecific degenerative changes. In a case PN, however, annulate lamellae were present in a small number of the muscle fibres. The annulate lamellae have been reported, to our knowledge, in the human skeletal muscles only in a few cases of polymyositis. In addition, two cases, one of PN and of arteritis with RA, showed fine filamentous inclusions in the muscle fibres. Changes were also noted in the motor end-plate. A sural nerve biopsy in a case of arteritis with RA showed changes both in axons and myelin sheaths, in addition to the changes in the blood vessels similar to those in the muscle.

No abstract

Most of the actions of sex hormones are mediated by specific cytosolic receptors in target tissues, translocating to the cell nucleus where they exert their effects (Buller & O'Malley, 1976; McEwen ef al., 1978). An effective means of monitoring 3.40 k 0.09 3.56k0.10 3.07f0.15' 2.52 k 0.06***