Archana Srivastava

Studies on mechanism(s) of antifertility action of gossypol in rat and hamster

This study was undertaken with a view to investigate the possible mechanism(s) of antifertility action of gossypol acetate in rats and hamsters. Adult male rats were treated by gavage with 30 mg/kg/day of gossypol for 7 weeks and adult male hamsters were treated similarly with 20 mg/kg/day gossypol for 8 weeks. The treatment caused a marked reduction in the weights of testis and epididymis. Histological examination of the testis in the two species revealed presence of seminiferous tubules showing varying degrees of damage along with a large number of normal tubules. Exfoliation of germ cells and spermatogenic arrest at spermatid stage was a common feature. Leydig cells presented normal morphological features. Though there was a reduction in the diameter of epididymal tubules, the epithelium did not show any morphological alterations. Examination of vasal flushings revealed marked reduction in sperm population and consisted of decapitated and immotile spermatozoa. Gossypol caused a significant reduction in the levels of total protein, RNA and DNA, and a marginal decrease in glycogen content in the testis. This was accompanied by a reduction in the activities of SDH and MDH. Except for LDH activity which showed a marked rise, there was no effect on glycolytic enzymes in the testis. The concentrations of glycerylphosphorylcholine and sialic acid were reduced in the cauda epididymis. The antifertility effects of gossypol appear to be due to its action both on testis as well as on epididymis.

Structure activity relationship of some 2,3-diaryl-2H-1-benzopyrans to their anti-implantation, estrogenic and antiestrogenic activities in rat

In an endeavour to develop potent anti-implantation agents, a new antiestrogen, CDRI 85/287 (2-(4-2-piperidinoethoxy)phenyl-3-phenyl(2H)benzo(b)pyran), virtually devoid of agonistic activity, was identified. The present study deals with anti-implantation and estrogen agonistic-antagonistic activities of four structural analogues of 85/287. Results show that none of the compounds induced vaginal cornification, even at doses as high as 2.5 mg/kg. Compounds having p-hydroxyphenyl group at position-3 or hydroxy group at position-7 showed better estrogen receptor affinity (6.6 and 25.3% E2) as well as antiestogenic activity. When 3-p-hydroxyphenyl was replaced by 3-p-methoxyphenyl, a marked reduction in the receptor affinity was observed. However, this compound was relatively more potent as an anti-implantation agent, possibly due to its conversion to hydroxylated metabolite in vivo. The provision of aminoethoxy side chain at para-position and a shift in the piperidinoethoxy side chain from position-4 to position-2 in these molecules resulted in a decrease in estrogenicity and increase in antagonistic property. Results are discussed with regard to molecular configuration, relative binding affinity of these compounds to their biological profile.

Androgen-Estrogen Synergy in the Regulation of Energy Metabolism in Epididymis and Vas Deferens of Rhesus Monkey

The possible physiological role of estrogen in the regulation of energy metabolism of epididymis and vas deferens of rhesus monkey was investigated. A few selected key enzymes of glycolysis (hexokinase, phosphofructokinase and pyruvate kinase) and TCA cycle (succinate dehydrogenase and malate dehydrogenase) were measured in these two organs of (a) castrated estrogen treated, (b) castrated estrogen + dihydrotestosterone (DHT) treated animals and compared with those in castrated and castrated + DHT treated animals. Results reveal that DHT stimulated the activities of all these enzymes whereas estrogen failed to stimulate any of the enzymes in castrated animals. However, estrogen in combination with DHT caused a marked stimulation of the enzymes and the response of the epididymis and vas deferens to combination treatment was significantly more than that caused by DHT alone. The results suggest that circulating estrogen in male has a physiological role and acts synergistically with androgen in regulating accessory sex organ function.

Activities and Androgenic Regulation of KREB Cycle Enzymes in the Epididymis and VAS Deferens of Rhesus Monkey

The activities of nine enzymes of the TCA cycle were estimated in the initial segment, caput, corpus and cauda segments of epididymis and vas deferens of adult rhesus monkey and expressed as units per mg DNA. These enzymes were also estimated in epididymal segments and vas deferens of castrated and castrated-androgen replaced monkeys as well. Results indicated higher activities of most of the enzymes in vas deferens as compared to epididymal segments. All the enzymes showed marked reduction in epididymis and vas deferens after castration, the effect being much more pronounced in the epididymis, than in the vas. Androgen replacement in castrated monkeys stimulated most of the enzymes markedly in epididymis and in the vas deferens as compared to their castrated values. The response of cauda and vas deferens to exogenous androgen treatment was however moderate, as compared to the other epididymal segments. The studies indicate that energy metabolism in the epididymis (as well as in the vas deferens) is strictly androgen dependent and the energy charge of these target organs is likely to fall appreciably after castration, which may in turn affect many energy dependent processes of these organs (e.g. absorption, secretion of specific substances etc.) which have been considered important for sperm maturation and survival.

Evaluation of STS-557 as an oral contraceptive in male rat

To examine the nature and site of post-testicular antifertility action of STS-557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one), male rats were given the steroid orally daily for 60 days. In doses of 1 and 5 mg per animal per day it had no effect on fertility at the end of 3 weeks of treatment. When the treatment was extended for 60 days, spermatogenic arrest and loss of libido were evident in animals treated with 5 mg dose; animals receiving 1 mg dose of steroid showed no decrease of spermatogenesis or sexual activity and their fertility remained unaffected. In 35-day-old growing rats the steroid produced inconsistent effects on spermatogenesis after a 15-day treatment period at 1 and 5 mg doses. Both in adult and in growing rats the steroid caused a significant reduction in the weights and secretory function of the epididymis and other accessory sex organs; a dose-dependent response was seen in all the sex organs. Evaluation in castrated rat model revealed that STS-557 is a weak anti-androgen. Although this steroid is a potent inhibitor of spermatogenesis, its inhibitory effect on Leydig cell function is a contraindication for its use as a male oral contraceptive.

Effect of an intrauterine contraceptive device on urea content of uterine fluid.

Urea concentration in uterine fluid was determined in 20 women fitted with Lippes loops IUDs, compared to that in 12 parous controls, to see whether urea accounts for the higher nitrogen content reported in uterine fluid in IUD users. The fluid was centrifuged and the supernatant analyzed enzymatically by the Tarnoky urease method. The urea concentration of the fluid from IUD users was significantly higher than that of controls, 181.8 vs 42.9 mcg/ml, p0.01. Uterine fluid urea content did not differ throughout the menstrual cycle. Blood urea levels did not differ between groups. The protein denaturant effects of urea may conceivably be detrimental to the preimplantation blastocyst.

The distribution of zinc in the subcellular fractions of the rhesus monkey testis.

The zinc content in the testis of sexually immature, adult, and efferent duct-ligated adult rhesus monkeys was determined by atomic absorption spectrophotometry. Zinc content (μg/g wet wt) was found to be high in adult testis (165.9) when compared to immature (68.9) or efferent duct-ligated (104.2) animals. Analysis of subcellular fractions revealed that the concentration of zinc (expressed in relation to protein) was maximum in the microsomal fraction. The possible significance of this trace metal as a constituent of membrane proteins and enzymes, and as an activator of mitochondrial function in testis, is discussed.

Zinc in the Epididymal and Vasal Spermatozoa of Rhesus Monkey (Macaca mulatta)

Zinc level in maturing spermatozoa collected from caput, corpus, and cauda regions of the epididymis and vas deferens of rhesus monkey was measured. Spermatozoa collected from the caput epididymis have the highest concentration of zinc (36 micrograms/10(8) spermatozoa). There was a marked reduction in the zinc content of corpus spermatozoa and a further decrease in the spermatozoa of cauda epididymis. Thus the zinc content of spermatozoa gradually decreases as they migrate from the caput to cauda epididymis. There was a significant increase in the zinc content of vasal spermatozoa as compared to those collected from the cauda region of epididymis.

LONG-TERM EFFECT OF A CONTINUOUS DAILY MICRODOSE OF NORGESTREL ON THE GENITAL ORGANS AND FERTILITY OF FEMALE RATS*

Abstract Daily oral administration (0.3 μg/animal) of norgestrel (17α-ethinyl-13β-ethyl- 17β-hydroxy-4-estren-3-one) for 12 months did not evoke any noteworthy ponderal or histologic changes in the genital organs of female rats. The total gonadotrophin content of the pituitary was somewhat reduced but the estrus cycle continued generally undisturbed. However, certain biochemical alterations were observed which denoted an impairment of metabolic status of the uterus. The failure of pregnancy noted in fertility performance tests was mainly due to inhibition of implantation and fetal resorption. It is suggested that a depression of metabolic status of the uterus by the progestogen is crucially involved in implantation failure and fetal resorption.