Alok K. Pal

Flowers of Hibiscus rosa-sinensis , a potential source of contragestative agent: II. Possible mode of action with reference to anti-implantation effect of the Benzene extract

Benzene extractives of Hibiscus rosa-sinensis flowers, administered during day 1-4 of gestation, exerted anti-implantation effect without affecting the tubal transport of zygote. On day 4, normal number of blastocyst was present in the uterus but they did not implant. However, as studied by pontamine blue reaction, it was evident that hyper-permeability of the endometrial capillaries which is the earliest known response of a receptive endometrium to any kind of deciduogenic stimulus was inhibited by the extract. The magnitude of decidualization, as assessed by weight of the traumatized uterine horn and supported by the histological pictures of the uteri was significantly lower in comparison to that of the controls. Ovarian structure exhibited signs of luteolysis. Inadequate progestational development of the endometrium due to interference with the conditioning of the uterus with progesterone during prenidatory phase of pregnancy has been suggested as the plausible cause of the extract-induced implantation failure.

Flowers of Hibiscus rosa-sinensis, a potential source of contragestative agent. III: Interceptive effect of benzene extract in mouse

In mouse, oral administration of the benzene extract of Hibiscus rosa-sinensis flowers at a dose level of 1 gm/kg body weight/day from day 5-8 of gestation led to termination of pregnancy in about 92% of the animals. The effect was associated with a significant fall in peripheral level of progesterone and increase in uterine acid phosphatase activity, as measured on day 10. The ovary exhibited signs of luteolysis, and the corpus luteal delta 5-3 beta -hydroxysteroid dehydrogenase activity decreased markedly. The interceptive effect of the extract was prevented completely by exogenous progesterone (1 mg/mouse/day) or chorionic gonadotropin (1 I.U./mouse/day) and partially (62.5%) by exogenous prolactin (500 micrograms/mouse/day). In unilaterally pregnant mouse having trauma-induced deciduomata in the sterile horn, the extract caused resorption of the fetuses, and regression of the deciduomata accompanied by reduction in weight of the ovaries. Luteolysis, may be due to interference with the luteotropic influence, and a consequent fall in plasma level of progesterone have been suggested as the plausible cause of termination of pregnancy.

FLOWERS OF HIBISCUS ROSA-SINENSIS, A POTENTIAL SOURCE OF CONTRAGESTATIVE AGENT : I. EFFECT OF BENZENE EXTRACT ON IMPLANTATION OF MOUSE

In mouse, the benzene extract of Hibiscus rosa-senensis flowers was administered at four different dose levels (250-1000 mg/kg body weight/day) from day 1-4 postcoitus. Anti-implantation response and associated changes in the uterine chemical composition were studied. With an increase in the dosage of the extract, the percentage of implantation failure increased. At the dose level of 1 gm/kg body weight, the extract led to failure of implantation in 93% of the mice. The effect was accompanied by adversely altered uterine weight, its protein content and alkaline and acid phosphatase activity. In another experiment, influence of the extract on uterine uptake of progesterone was studied in bilaterally ovariectomized mice treated with or without estrogen. It exerted neither inhibitory nor stimulatory influence on uterine progesterone uptake in untreated castrated mice but the estrogen-induced increase in the uptake level was significantly inhibited by the extract. Failure of uterine bed preparation due to antiestrogenic potentiality of the extract has been discussed as the plausible cause of implantation failure.

A probe into the possible mechanism underlying the interceptive action of aristolic acid

Oral administration of aristolic acid (90 mg/kg body weight) on day 6 pregnant and pseudopregnant mice resulted in the termination of pregnancy with in utero fetal death but the length of pseudopregnancy remained unaffected. Peripheral level of progesterone remained statistically uninfluenced in both conditions and exogenous progesterone failed to prevent aristolic acid-induced pregnancy loss, both of which rule out the involvement of luteolysis as the causal factor for the termination of pregnancy. In another experiment, aristolic acid was found to have no inhibitory effect over the maintenance of decidual cell reaction which indicates no inhibitory influence of the compound on uterine utilization of progesterone but points to the fact that presence of concepts is an essential component in the array of mechanism(s) leading to the termination of pregnancy. Probable toxic effect of aristolic acid on the concepts is discussed.

PREGNANT MARE'S SERUM GONADOTROPHIN: II. REVERSAL OF THE ANTIFERTILITY FACULTY OF PREGNANT MARE'S SERUM GONADOTROPHIN BY USING CLOMIPHENE CITRATE OR RESERPINE IN RATS*

Pregnant mares serum gonadotropin (PMSG) 10 IU was injected in rats on Day 5 of pregnancy. Counting of implanted blastocysts was done on Day 8 of pregnancy through a midventral incision. The corpora lutea were noted to be significantly smaller (p less than .001) than controls. Autopsies were done on Day 16 of pregnancy. In some rats, clomiphene citrate (Clomid) was used as an antiestrogenic in a dose of .3 mg/kg injected sc on Days 5, 7, and 9. In others, reserpine was injected sc in a dose of .5 mg/kg on Days 5, 7, 9, 11, and 13 of pregnancy. The single injection of PMSG resulted in complete resorption of fetuses and placentae by Day 16. The Clomid reversed the antifertility action of PMSG and maintained growth of fetuses, placentae, and corpora lutea with 100% fetal survival. It is assumed that excessive luteinizing hormone (LH), as induced by the PMSG, stimulates ovarian estrogen. Since reserpine initiates prolactin release and inhibits LH release, the direct antagonism of prolactin at the luteal level may take place by inhibiting the enzyme activity of 20alpha-hydroxysteroid dehydrogenase.

Primordial Germ Cell Migration in the Rat: Preliminary Evidence for a Role of Galactosyltransferase

Abstract The precise cellular mechanism of primordial germ cell (PGC) migration remains unknown. Cell surface galactosyltransferase (GalTase) is known to play unique roles in the process of locomotion of many migratory cells. With an objective to seek evidence for possible involvement of GalTase in the migratory process of PGC, we evaluated germ cell migration in the rat following experimental modulation of embryonic GalTase activity. Pregnant rats were laparotomized under anesthesia on Day 10 of pregnancy. While embryos of one uterine horn received lysozyme (100 μg/fetus), those of the other received α-lactalbumin (LA; 100 μg/fetus), N-acetylglucosamine (GlcNAc; 250 nmole/fetus), uridine 5′-monophosphate (UMP; 2.5 μmole/fetus), uridine diphosphate-galactose (UDP-gal; 250 nmole/fetus), or a combination of 250 nmole of UDP-gal and 2.5 μmole of UMP/fetus. Between gestation Days 12 and 14, embryos were dissected out and processed for histochemical localization of PGC on the basis of binding of Dolichos biflorus agglutinin on the surface glycoconjugate of the germ cells. The number of PGC in each embryo was counted. There was a daywise increase in the number of PGC in all groups. As compared with lysozyme-exposed controls, the numbers of PGCs at the day-specific sites on all days of examination were significantly lower in the LA- as well as GlcNAc-exposed groups. UMP or UDP-gal individually exerted little or no influence, while the total PGC count rose significantly over the respective control values under simultaneous exposure to UMP and UDP-gal. The present findings suggest a likely catalytic role of GalTase in the process of germ cell migration.

Antiovulatory faculty of the flower of Malvaviscus conzattii

The methanol extract of the flowers of Malvaviscus conzattii was orally administered in cycling unilaterally ovariectomized (ULO) rats at a dose level of 1 g/kg body wt/day for one or two cycles. The effect of the extract on the length of the cycle and ULO‐induced compensatory ovulation and hypertrophy of the remaining ovary was assessed on the first oestrus following completion of treatment. Although no adverse influence was observed on either of the parameters, the cycle length was significantly prolonged and both the compensatory phenomena underwent significant inhibition after treatment of the extract for two consecutive cycles. In another experiment, the extract was found to be ineffective in preventing exogenous gonadotropin(s)‐induced ovulation in immature and sub‐adult rats. It is, therefore, suggested that the extract might have interfered with the synthesis and/or release of gonadotropin(s) from the pituitary while the ovarian utilization of gonadotropin(s) remained unaffected. The LD50 of the extract was found to be 20 g/kg body wt. Copyright

Disruption of pregnancy in mouse by Aristolic acid: I. Plausible explanation in relation to early pregnancy events

Aristolic acid (AA), obtained from Aristolochia indica Linn, disrupted nidation in mice when administered on Day 1 of pregnancy. The implantation inhibiting effect of the compound was assessed with respect to certain parameters which are characteristics of early pregnancy, such as tubal transport of ova into the uterus, hyperpermeability of the endometrial capillaries, increase in uterine weight and total protein content, endometrial bed preparation and changes in uterine phosphatase enzymes during Days 4-6 of pregnancy. The compound did not affect tubal transport of eggs, but the uterine blue reaction, caused by extravasation of the dye, pontamine blue, at future implantation sites was inhibited significantly in treated mice. Histological picture of the uterus revealed AA-induced impairment of development (i.e. decidualization) and reconciled with decreases found in uterine weight and its total protein contents in treated animals. In control untreated mice, specific uterine alkaline phosphatase (ALP) activity increased significantly from Days 4 through 6 of pregnancy, but this was prevented in treated mice. On the other hand, specific uterine acid phosphatase (AP) activity was high on Day 5, while in treated mice uterine AP activity remained low during Days 4 and 5 and increased significantly thereafter. It was inferred that AA interferes with steroidal conditioning of the uterus and renders it hostile to ovum implantation.

Estrogen and female fertility: I. failure of human chorionic gonadotropin or reserpine in the reversal of pregnancy wastage by estradiol cyclopentylpropionate.

Failure of human chorionic gonadotropin (HCG) or reserpine in the reversal of pregnancy wastage by estradiol cyclopentylpropionate (ECP) in rats is reported. 10 mcg ECP on Day 5 of pregnancy resulted in complete resorption of embryos with a significant reduction in ovarian (p less than .005) and luteal weight (p less than .001). Progesterone or prolactin in combination with ECP were found to maintain normal pregnancy. Failure to maintain pregnancy by HCG or reserpine in this situation revealed that neither luteinizing hormone deficiency nor its excessive stimulation by ECP is the cause of pregnancy wastage in rats.

Pregnant Mare’s Serum gonadotropin. III. Hemispaying and the Reversal of the Antifertility Faculty of Pregnant Mare’s Serum Gonadotropin *

A single injection of 10 IU of pregnant mares serum gonadotropin (PMSG) on day 5 of pregancy caused wastage of the fetoplacental unit by day 16 of pregnancy. Semispaying, which seems to subtract approximately 50% of the ovarian steroid contribution, at 24, 48, and 72 hours following the PMSG schedule prevented the antifertility faculty of the hormone preparation. However, hemicastration at 96 hours following the gonadotropin regimen was found to be ineffective, and 100% of the test animals showed complete termination of pregnancy. Experimental data collectively tempt us to propose that an estrogen excess, particularly of follicular origin in both ovaries, is essential for more than 72 hours following gonadotropin sensitization before the antifertility faculty of PMSG can be demonstrated.