The zoapatle. X. The in vitro effect of zoapatle aqueous crude extract (ZACE) and histamine upon rat and guinea pig uterine strips.

In vitro histamine response in rat and guinea pig uterine strips was similar to the one observed with zoapatle aqueous crude extract (ZACE). The relaxing effect elicited by ZACE/tomentosa on the in vitro rat uterine strips was not mediated by activation of H-2 histamine receptors; moreover, the increase on uterine contractility elicited by ZACE/tomentosa on the in vitro guinea pig uterine strip was not mediated through the activation of H-1 histamine receptors.

The zoapatle. XI. Effects elicited by Montanoa tomentosa and Montanoa frutescens on rat uterine strips.

Zoapatle aqueous crude extract (ZACE) obtained from Montanoa tomentosa (M.t.) inhibits the in vitro spontaneous contractility pattern of rat uterine tissue. The opposite effect was observed with ZACE from Montanoa frutescens (M.f.) in the same preparation. Both plant extracts, M.t. and M.f., increased the in vitro spontaneous contractility pattern in the uterine guinea pig assay. In depolarized uterine tissue, propranolol (beta-blocker) inhibited the relaxing effect induced by M.t.. Atropine (cholinergic antagonist) abolished the increase in uterus contractility produced by the presence of M.f.

The zoapatle. VII. Antiimplantation effect in the rat of zoapatle aqueous crude extract (ZACE) from Montanoa tomentosa and Montanoa frutescens.

Intrauterine administration of zoapatle aqueous crude extract (ZACE) from Montanoa frutescens on the fourth day of rat pregnancy, at concentrations equivalent to 50 mg and 5 mg of dry leaves, was associated with total inhibition of implantation sites. On the other hand, ZACE from Montanoa tomentosa equivalent to 50 and/or 100 mg of dry leaves, prepared and administered in the same fashion, did not inhibit the number of implants by day 11 of pregnancy. However, most implants were found abnormal, of blue color, poor orientation or spacing; these morphological changes could be considered as reabsorption sites.

The zoapatle. VIII. Ultrastructural changes in endometrium of rats.

Intrauterine administration of Zoapatle aqueous crude extract (ZACE) prepared from Montanoa tomentosa s.s.p. tomentosa, on day 4 of pregnancy, did not alter the normal uterine morphological changes by days 5 and 8 of pregnancy in the rat. On the other hand, ZACE made from Montanoa frutescens caused profound alterations on the uterine structures, such as: focal loss of epithelial lining, thickened blood vessels and alterations in stroma cells in rat endometrium. Morphological alterations correlate well with the antiimplantation effect associated with the intrauterine administration of these plant extracts. Scanning electron micrographs of leaves from Montanoa tomentosa and Montanoa frutescens revealed striking differences in glandular secretion and trichomes.

The zoapatle II--botanical and ecological determinants.

A collection of Montanoa (Cerv) specimens was conducted throughout Mexico. Twenty-one specimens were classified, some of them grown in the greenhouse and transplanted in an agricultural experimental field station in the Valley of Mexico. In vitro uterotonic potency was assayed and the results expressed as equivalents of oxytocine, by using estrogenized guinea pig uterine strips. A great variation of uterotonic potency was observed among the wild plants. A clear decrease and uniformity of uterotonic potency was found in plants grown in the experimental field. The study points out the importance of ecological variations in expression of the plant's biological activity.

PIP: 21 specimens of the zoapatle Montanoa (Cerv) plant were collected from sites throughout Mexico with a variety of climatic, humidity, soil composition, and altitude conditions to assess their uterotonic properties. Some plants were then grown in an agricultural experimental field station of the National Institute of Agricultural Research, where all the variables were known, allowing for a valid comparison between species and plants. In vitro uterotonic potency was assayed and the results expressed as equivalents of oxytocin. The wild plants were found to vary greatly in uterotonic potency, perhaps reflecting differences in ecological conditions. The most active uterotonic zoapatle aqueous crude extract was the Montanoa frutescens, and the least active was M. mollissima, the former having approximately 4 times the uterotonic potency of the latter. The plants grown in the agricultural field station showed a considerable decrease in uterotonic potency, but valid comparisons must await assay in winter to match the stage in the plant life when the wild samples were assayed. Plant age, the part of the plant from which the uterotonic principle is extracted, climate, altitude, and soil constituents are other possible influences on uterotonic potency. A sample of the zoapatle aqueous crude extract with the highest uterotonic potency will be assayed for its luteolytic activity in an animal model.

The zoapatle III--biological and uterotonic properties of aqueous plant extract.

Differences in uterotonic activity were observed between zoapatle Montanoa (Cerv.), plants growing in their natural habitat and plants growing in an experimental agricultural plot. Details of an in vitro analogic model for assaying uterotonic potency in guinea pig strips is described. Important species differences on the uterine response to zoapatle aqueous crude extract were noticed in rats, hamsters, guinea pigs, cats and Rhesus monkeys. The need for proper biological evaluation of chemical substances already isolated from zoapatle specimens, is mentioned, and the advantages of working with zoapatle specimens grown under controlled ecological conditions are pointed out.

PIP: An in vitro analogic method for comparing the uterotonic potency of dialysed zoapatle aqueous crude extract (DZ-ZACE) with oxytocin is described. Uterine strips from estrogenized guinea pigs were selected as the appropriate animal model after trials with estrogenized rats, hamsters, cats, and Rhesus monkeys. Results of the in vitro uterotonic effect produced by 21 different zoapatle Montanoa plants collected from different parts of Mexico and grown in an experimental agricultural field station indicate considerable difference, with less variation in uterotonic oxytocin/equivalents among the plants grown at the field station than in wild specimens. The general reduction in uterotonic potency of plants grown at the field station may be due to differences in the time of collection: wild specimens were collected in winter 1980, while field station specimens were collected just after flowering in early summer 1981. The findings clearly demonstrate the influence of the plant environment on the expression of biological response. Because of its lack of toxicity, abundance, ease of production, and the availability of an efficient analogic in vitro assay for the evaluation of relative uterotonic potency, ZACE may eventually be the source of a new agent to intercept pregnancy.

The zoapatle V--the effect of kauradienoic acid upon uterine contractility.

Kauradienoic acid was obtained from the hexanic extract of M. tomentosa (Cerv) leaves by chromatographic separation. This substance influenced the in vitro contractility of the rat, dog and guinea pig uterine strips. It also induced strong contractions of the guinea pig uterus in vivo when administered intravenously, without changes on arterial blood pressure. The effects produced by the plant infusion, the hexanic extract and pure species were compared. The hexanic of other utero-active compounds in M. tomentosa in addition to those already described is discussed.

PIP: The investigation of uterotonic effects of the hexanic extract (HE) of M. tomentosa leaves, as well as that (-)-kaura-9(11), 16-dien-19-oic acid, henceforth referred to as kauradienoic acid (KA) is described. Pregnant and nonpregnant female Wistar rats, guinea pigs, and dogs were used in this study. Strips obtained from 5 animals had spontaneous rhythmical contractions constant in amplitude and frequency. Muscular tone and frequency of contractions were notably increased by addition of 20 ul/ml of zoapatle aqueous crude extract (ZACE). The preparation returned to the original spontaneous contractility pattern after washing with a modified Ringer solution. Strips obtained from 5 gravid guinea pigs showed scarce spontaneous contractility which was strongly augmented by addition of ZACE. Regular spontaneous contractions were observed in over 30 assays of uterine strips obtained from 5 nongravid rats. The addition of ZACE drastically inhibited the spontaneous contractility. Constant and reproducible results were obtained in gravid rats by addition of ZACE. A gradual decrease in amplitude of contractions was observed. The addition of ZACE depressed the uterine contractility (UC) of 8 uterine strips from 2 animals. The addition of ZACE in gravid dogs in 8 uterine strips was accompanied by an increase of muscular tonus and frequency. A gradual decrease in the amplitude of the rat spontaneous UC was an effect produced by the HE. Addition of water suspension of HE elicited an immediate increase of guinea pig's uterine motility. Results were similar with those observed with ZACE. KA inhibited the "in vitro" rat UC and increased the "in vitro" guinea pig contractions of uterine musculature in a similar fashion as observed with ZACE and HE.