Estrogenic behavior of 2(o-chlorophenyl)-2-(p-chlorophenyl)-1,1,1-trichloroethane and its homologues.

Eight chlorinated hydrocarbons were tested for their ability to compete with ³H-estradiol-17β for specific binding proteins in uterine cytoplasm from immature rats. The binding was assayed on 5–20% sucrose density gradients. 2(o-Chlorophenyl)-1,1,1-trichloroethane (o,p′-DDT) and 2(o-chlorophenyl)-2-(p-chloropenyl)-1,1-dichloroethylene (o,p′-DDE) (1·4 × 10^?4M) competed with ³H-estradiol-17β (8·7 × 10^?9 M) for binding to the “8 S receptor” in the cytomplasm. 2,2-Bis-(p-chlorophenyl)-1,1,1-trichloroethane (p,p′-DDT), 2,2-bis-(p-chlorophenyl)-1,1-dichloroethylene (p,p′-DDE), 2,2-bis-(p-chlorophenyl)-1,1-dichloroethane (p,p′-DDD), 2(m-chlorophenyl)-2-(p-chlorophenyl)-1,1-dichloroethane (m,p′-DDD), 2(o-chlorophenyl)-2-(p-chlorophenyl)-1,1-dichloroethylene (o,p′-DDD) and bis-(p-chlorophenyl)-1,1-dichloroacetate (DDA) did not compete at 1sd4 × 10^?4 M. Transfer of the receptor-bound compounds into the nuclei was examined using similar competition techniques. o,p′-DDT and o,p′-DDE competed with estradiol binding in the nuclei. These studies indicate that o,p′-DDT and o,p′-DDE at high concentrations act as estrogens as measured by their ability to compete with estradiol-17β for binding to the uterine cytopoasmic receptor and in the transfer and binding of estradiol in the nuclei of uterine cells.     

Stimulation of uterine deoxyribonucleic acid synthesis by 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)ethane (o,p′-DDT)

The administration of 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p′-DDT) to immature female rats produced a maximum increase in uterine wet weight and DNA synthesis measured by tritiated thymidine incorporation into uterine DNA 24 hr after treatment. These responses were maximal at a dose of 250–1000 mg/kg of (o,p′-DDT); half-maximal responses occurred in the range of 10–40 mg/kg. These responses were specific for o,p′-DDT, since (o,p′-DDT)T was much less potent. 17β-Estradiol and (o,p′-DDT) also produced increases in total uterine DNA content and in total uterine protein content. The uterine responses to maximum doses of 17β-estradiol and (o,p′-DDT) were not additive, suggesting that both compounds interact with the same receptor. In a series of experiments, the administration of 250 mg/kg of (o,p′-DDT) produced increases in uterine weight that were the same as those seem after 17β-estradiol treatment, increases in DNA synthesis that were 60–80 per cent of those produced by 17β-estradiol and an increase in total uterine DNA that was 66 per cent of that observed after 17β-estradiol treatment. 17β-Estradiol and (o,p′-DDT) also produced significant increases in uterine wet weight and DNA synthesis in ovariectomized/adrenalectomized rats, indicating that the effects of the pesticide are not mediated via adrenal steroids.     

Effects of 1-(o-chlorophenyl)-1-(p-chloro-phenyl)-2,2-dichloroethane and puromycin on adrenocorticotropic hormone-induced steroidogenesis and on amino acid incorporation in slices of dog adrenal cortex

In adrenal slices from control dogs, ACTH in vitro produced a 3-fold increase in steroid production but had no effect on incorporation of ¹⁴C-labeled amino acids into adrenal cortical protein. Puromycin in vitro partially inhibited the steroidogenic response to ACTH and almost completely inhibited amino acid incorporation. Administration in vivo of 1-(o-chlorophenyl)-1-(p-chlorophenyl)-2, 2-dichloroethane (o,p'-DDD), 2–48 hr prior to adrenalectomy, completely blocked the steroidogenic response to ACTH and had the paradoxical effect of producing a marked increase in incorporation of labeled amino acids into protein. Possible implications of these data are presented.     

Effects of nonylphenol, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), and pentachlorophenol on the adult female guinea pig reproductive tract

The guinea pig exhibits cyclic and luteal similarities to the human, a feature not present in other small experimental animals such as rats, mice, or rabbits. Studies were undertaken to investigate the in vivo effects of three persistent environmental xenobiotics (nonylphenol, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene [p,p'-DDE], and pentachlorophenol) on the microanatomy of the adult female guinea pig reproductive system. The effects brought about by these compounds (40 mg/kg/day) were compared to those caused by the synthetic estrogen diethylstilbestrol (DES; 50 microg/kg/day). Adult female guinea pigs, intact and castrated, were treated with 14 daily subcutaneous (s.c.) doses of one of these agents. The 50% decline in the weight of the tract that occurred following castration, was prevented by administration of nonylphenol, p,p'-DDE, and DES, but not of pentachlorophenol. Nonylphenol produced weak estrogenic stimulation of the tract of intact animals and maintained a relatively normal histologic appearance in castrated animals. Focal mucinous metaplasia of the endometrium, however, was observed in both groups. Treatment of intact and castrated animals with p,p'-DDE resulted in cystic hyperplasia and mucinous metaplasia of the endometrium, hyperplasia of the cervical epithelium, estrogenic stimulation of the vagina, and dilation of the rete ovarii. Treatment of intact or castrated animals with DES resulted in effects that were qualitatively similar to those caused by p,p'-DDE. The appearance of the vaginal epithelium, however, was abnormal and the rete ovarii were less dilated. Pentachlorophenol had minimal effect on the histology of the tract of castrated or intact animals. These data support our hypothesis that some environmental toxicants can substitute for estradiol in regulating the microanatomy of the female reproductive tract. They indicate the potential of these compounds to act as endocrine disrupting agents.     

Plasma level monitoring of mitotane (o,p'-DDD) and its metabolite (o,p'-DDE) during long-term treatment of cushing's disease with low doses

Summary. Mitotane (o,p'-DDD) can be used for the treatment of various adrenocortical diseases such as Cushing's syndrome, but the usual doses of 6–8 g per day are often associated with severe adverse effects.This paper reports the results of much lower doses of o,p'-DDD (0.5–2 g per day) in two patients with Cushing's disease over periods of 8 and 5 years, respectively, under concomitant monitoring of the plasma levels of the parent drug and its major metabolite, o,p'-DDE.It became apparent that o,p'-DDD and o,p'-DDE have a strong tendency to accumulate in the body due to their high lipophilicity. As a consequence, changes in dose regimens had long lag times before they were reflected in plasma levels and once an increase or decrease had started one had to be careful not to cause overshoot.Steady state plasma levels of o,p'-DDD between 5–10 g/ml appeared sufficient to induce and to maintain remission of the disease, which was accompanied with normal cortisol levels in plasma and urine. DDD-levels below 5 g/ml for several weeks may lead to relapses, whereas DDD-levels over 10 g/ml gave rise to side effects. On the other hand, o,p'-DDE seemed inactive at levels up to 4 g/ml in plasma.     

Neuropeptide Y1- and Y2-receptor-mediated cardiovascular effects in the anesthetized guinea pig, rat, and rabbit

Neuropeptide Y (NPY) causes vasoconstriction through Y1-receptors and inhibits vagal bradycardia through presynaptic Y2-receptors. These effects of NPY were investigated in anesthetized guinea pigs, rats, and rabbits to find the most suitable species for evaluation of Y1- and Y2-active agents in vivo. The increase in blood pressure (through Y1) of lower doses of NPY was similar in the three species (ED50, 0.9 +/- 0.13, 0.8 +/- 0.39, and 0.6 +/- 0.09 nmol/kg, respectively), but higher doses had depressor effects in four of six rats. Vagal bradycardia, induced by electrical stimulation of the right cervical vagus nerve, was inhibited by NPY in the guinea pig and in the rat (ED35, 3.5 +/- 0.46 and 11.2 +/- 1.79 nmol/kg, respectively; p < 0.05) but not in the rabbit. In the guinea pig, the Y2-receptor-preferring fragment NPY(3-36) and the selective Y1-receptor antagonist H 409/22 were used to confirm that the increase in blood pressure was mediated solely through the Y1-receptor and the vagal inhibition solely through the Y2-receptor. Aside from the cardiovascular effects, NPY caused a decrease in the body temperature and inhibited vagal bronchoconstriction in this species. Considering that NPY may cause depressor effects in the rat and has no effect on the vagal bradycardia in the rabbit, the guinea pig is preferable to both these species for assessment of Y1- and Y2-receptor-active agents in vivo.     

Electromechanical effects of bPTH-(1-34) on rabbit sinus node cells and guinea pig papillary muscles

The effects of bPTH-(1-34), a synthetic preparation of bovine parathyroid hormone containing the first 34 amino acids, on electromechanical activity of isolated rabbit sinus node cells and guinea pig papillary muscles were examined by microelectrode techniques. In sinus node cells, bPTH-(1-34) (10(-7) M) decreased the cycle length of spontaneous firing (SPCL) accompanied by an increase in the maximum upstroke velocity at phase 0 (dV/dtmax) without affecting the amplitude of the action potential (APA) or the maximum diastolic potential (MDP). All the effects of bPTH-(1-34) on sinus node cells were abolished by verapamil (5 X 10(-7) M), but not by pindolol (2 X 10(-7) M). In constantly driven guinea pig papillary muscles, bPTH-(1-34) caused a positive inotropic effect (+31%). The parameters of the action potential were not significantly affected. This inotropic effect of bPTH-(1-34) was inhibited by pretreatment with verapamil or a low calcium medium (0.12 mM), but was not affected by pindolol. In contrast, ryanodine (2 X 10(-6) M), an inhibitor of internal Ca2+ release, which decreased the contraction with a prolongation of the action potential duration augmented the inotropic effect of bPTH-(1-34). In papillary muscles depolarized by 26 mM [K+]O, bPTH-(1-34) enhanced the slow action potential. In voltage clamp experiments using a single sucrose-gap method, bPTH-(1-34) caused an increase in the peak amplitude of the slow inward current, while it did not affect the outward current.(ABSTRACT TRUNCATED AT 250 WORDS)