Reproductive effects of endosulfan on male offspring of rats exposed during pregnancy and lactation.

1. The reproductive effects of endosulfan on the male offspring of rats were examined. Dams were treated orally with 0, 1.5 or 3.0 mg endosulfan/kg from day 15 of pregnancy to postnatal day (PND) 21 of lactation. The male offspring rats were investigated at PND 65 or 140, corresponding to the pubertal and adulthood stage of development. 2. The dose of 3.0 mg endosulfan/kg induced a decrease in maternal body weight during pregnancy, but litter size and mean birth weight were not affected. Similarly, the age at testis descent and preputial separation was not affected on the male offspring. 3. The daily sperm production (x10(6)) was permanently decreased in the highest dose group when investigated at puberty and at adulthood. At the lowest dose, however, the daily sperm production was significantly reduced only at puberty. 4. Histologically, the percentage of seminiferous tubules showing complete spermatogenesis was significantly decreased at puberty. This finding may explain the decrease in daily sperm production observed in the endosulfan-exposed male rats. 5. The results of this study show that low doses of endosulfan have no apparent effect on developmental landmarks or on the weight of reproductive and accessory sex organ. Daily sperm production was the most susceptible endpoint in the male offspring exposed to endosulfan during pregnancy and lactation. To further understand the reproductive effects of endosulfan on male rat offspring, additional reproductive and toxicokinetic studies should be carried out to determine the extent of endosulfan exposure in male rat offspring in utero and during lactation.

Influência da administraçäo de extratos de duas plantas calcinogênicas sobre a fertilidade de ratos / Effect of calcinogenic plant extracts on rat fertility

Investigou-se o efeito de extratos aquosos de Solanum malacoxylon (Sendter) Solanaceae (SM) (sin.: S. glaucophyllum) e Nierembergia veitchii (Hook) Solanaceae (NV), plantas calcinogênicas encontradas no Brasil, sobre a reproduçäo de ratos e sobre suas progênies. No experimento 1, ratos e ratas Wistar, em número variável conforme o grupo, receberam por via oral, durante os 40 dias anteriores ao acasalamento, extrato aquoso de ambas as plantas em dosagem equivalente à administraçäo diária de 10,9gxkg elevado a menos um de planta seca. Os resultados foram comparados com os de um grupo tratado diariamente com vitamina D3 (3,0mgxkg elevado a menos um) e com os de um grupo-controle (salina). No experimento 2, ratas prenhes receberam, por via oral, três diferentes doses dos extratos de ambas as plantas (equivalentes à administraçäo diária de 5,4; 10,9 e 21,7gxkg elevado a menos um de planta seca), durante toda a gestaçäo. Os resultados foram comparados com três grupos tratados com vitamina D3 (0,75; 2,25 e 3,75mgxkg elevado a menos um) e um grupo-controle (salina). Quando administradas antes da gestaçäo, o ganho de peso das fêmeas e a fertilidade foram reduzidos nos grupos tratados com SM (11 por cento) e vitamina D3 (11 por cento). No grupo tratado com NV, a fertilidade também foi reduzida (25 por cento), mas o desenvolvimento ponderal durante o tratamento näo foi afetado. Nos grupos tratados com SM e vitamina D3 anterior à gestaçäo, o número de filhotes por ninhada foi reduzido, assim como o seu peso ao nascer. Características de desenvolvimento e desempenho físico dos filhotes näo foram afetados em nenhum dos grupos. O tratamento das fêmeas com extrato aquoso de SM durante a gestaçäo causou reduçäo significativa e dose-dependente nas características reprodutivas estudadas. O mesmo foi observado com as fêmeas tratadas com vitamina D3. Com o extrato aquoso de NV näo foram observadas reduçöes nas taxas reprodutivas, quando as fêmeas foram tratadas durante a gestaçäo. Com as doses 10,9 e 21,7xkg elevado a menos um de NV foram observadas anomalias morfológicas fetais (2,3 e 0,1 por cento, respectivamente), também presentes nos filhotes de fêmeas tratadas com vitamina D3 (2,25mgxkg elevado a menos um). A presença de vitamina D3 e seus metabólitos nas plantas calcinogênicas provavelmente é responsável pela infertilidade observada, näo somente devido à toxicidade sistêmica, mas também devido aos seus efeitos específicos sobre o aparelho reprodutor

Carrier-mediated outward transport of dopamine from adrenergic varicosities of the vas deferens of reserpine-pretreated rats.

In vasa deferentia of reserpine-pretreated rats a carrier-mediated (i.e., desipramine-sensitive) outward transport of endogenous dopamine was induced by either tyramine or ouabain. The dopamine taking part in the efflux induced by tyramine (and the concomitant efflux of DOPAC) was derived from ongoing synthesis of dopamine. Inhibition of MAO trebled the rate of spontaneous efflux of dopamine and reduced the spontaneous efflux of DOPAC by 90%. After inhibition of MAO, desipramine caused a further five-fold increase in the basal efflux of dopamine with no change in the basal efflux of DOPAC. Inhibition of COMT failed to affect the spontaneous efflux of dopamine but increased that of DOPAC. It is concluded that, after depletion of the noradrenaline stores by pretreatment with reserpine, an outward transport of axoplasmic dopamine is induced by the same mechanisms that (without any pretreatment with reserpine) are known to initiate an outward transport of noradrenaline.

Pharmacological investigations on Achyrocline satureioides (LAM.) DC., Compositae.

Achyrocline satureioides (Lam.) DC. inflorescences have been used as remedies in folk medicine for the treatment of a variety of human ailments, particularly those of the gastrointestinal tract. Different extracts of inflorescences have been tested for anti-inflammatory, analgesic, antispasmodic, constipating and sedative activities. The aqueous extracts (maceration and decoction) and ethanolic macerate exhibited an inhibition of the carrageenan-induced rat paw oedema at a dose range of 75-500 mg kg-1 i.p., and also showed analgesic effect with the acetic acid-induced writhing test in mice. The gastrointestinal propulsion of a charcoal suspension was not affected significantly by any extract, at a dose of 200 mg kg-1 p.o., in mice. The aqueous decoction increased pentobarbital-induced sleeping time, at doses of 200 and 500 mg kg-1 i.p. and p.o., in mice. The ethanolic macerate inhibited contractions induced by acetylcholine, histamine, noradrenaline and barium chloride in four different smooth muscle tissues. The antispasmodic and anti-inflammatory activities were reproduced with quercetin, luteolin and quercetin 3-methyl ether, flavonoids that have been isolated from this plant. A partial evaluation of the toxicity of the extracts was also performed. The pharmacological effects assayed are discussed in relation to the chemical constituents of this plant and its popular use in gastrointestinal disturbances, and inflammatory conditions could be related to the presence of the flavonoids.

The mechanism of the 3H-noradrenaline releasing effect of various substrates of uptake1: multifactorial induction of outward transport.

The mechanism of action of indirectly acting sympathomimetic amines was studied in the rat vas deferens, after inhibition of vesicular uptake (by reserpine), of MAO (by pargyline) and of COMT (by U-0521). 1. Km-values for the neuronal uptake of 12 substrates were determined as the IC50 of the unlabelled substrate inhibiting the initial rate of neuronal uptake of 0.2 mumol/l 3H-(-)-noradrenaline. The IC50 ranged from 0.35 mumol/l (for(+)-amphetamine) to 44.3 mumol/l (for 5-HT). The Vmax (determined for 8 substrates) was substrate-dependent. 2. Tissues were loaded with 0.2 mumol/l 3H-(-)-noradrenaline and then washed out with amine-free solution. All 12 substrates of uptake1 induced an outward transport of 3H-noradrenaline, and equieffective concentrations were positively correlated with Km. Moreover, the EC50 for release greatly exceeded Km. It is proposed that this discrepancy between EC50 and Km is indicative of the fact that at least four factors (each one in strict dependence on Km) contribute to the initiation of outward transport of 3H-noradreanline: a) the appearance of the carrier on the inside of the axonal membrane (facilitated exchange diffusion), b) the co-transport of Na+, c) the co-transport of Cl- (both lowering the Km for 3H-noradrenaline at the inside carrier), and d) inhibition of the re-uptake of released 3H-noradrenaline (through competition for the outside carrier). 3. At least for amezinium, Vmax appears to limit the maximum rate of outward transport. 4. For some substrates (especially for the highly lipophilic ones) bell-shaped concentration-release curves were obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism of the 3H-noradrenaline releasing effect of various substrates of uptake1: role of monoamine oxidase and of vesicularly stored 3H-noradrenaline.

The mechanism of action of indirectly acting sympathomimetic amines was studied in vasa deferentia of unpretreated rats (COMT inhibited), preloaded with 3H-noradrenaline. 1. Concentration-release curves were obtained for 12 unlabelled indirectly acting amines. From differences between these results and those in an accompanying report (involving tissues from rats pretreated with reserpine and pargyline), it is concluded that a "mobilisation" of vesicular 3H-noradrenaline is required for high and sustained rates of outward transport of 3H-noradrenaline from intact adrenergic varicosities. 2. Experiments with a reserpine-like compound (Ro 4-1284) supported the view that a "mobilisation" of vesicular 3H-noradrenaline is required for substantial release. 3. An atypical time course of release and abnormally high rates of release were observed in the presence of excessive concentrations of (+)-amphetamine. Such atypical effects are ascribed to the of basic amines to increase the intravesicular pH. 4. Analysis of the ratio NA/DOPEG (rate of efflux of 3H-noradrenaline/rate of efflux of 3H-DOPEG) indicated that the inward transport (by uptake) of substrates of MAO fails to achieve axoplasmic concentrations which saturate MAO. Inhibition (or saturation) of MAO is not a prerequisite for the initiation of outward transport. 5. A larger fraction of vesicular 3H-noradrenaline is accessible to equireleasing concentrations of (+)-amphetamine (an inhibitor of MAO) than of tyramine (a substrate of MAO). 6. From the present and the accompanying report it is concluded that "substantial and sustained indirect sympathomimetic effects" are to be expected for substrates of uptake which additionally mobilise vesicular noradrenaline. However, this "mobilisation" does not seem to involve a change in intravesicular pH, except at excessive concentrations.

Mechanism of action of indirectly acting sympathomimetic amines.

The mode of action of indirectly acting sympathomimetic amines was analysed in the rat vas deferens (preloaded with 3H-(-)-noradrenaline). When monoamine oxidase (MAO), catechol-O-methyltransferase and vesicular uptake were inhibited (i.e., when the concentration of 3H-noradrenaline in the axoplasm was high), all substrates of neuronal uptake induced a carrier-mediated outward transport of 3H-noradrenaline, in strict dependence on the Km for neuronal uptake of the substrate. However, when MAO and vesicular uptake were not inhibited, some of the substrates of neuronal uptake were better releasers of 3H-noradrenaline than others; obviously, when the axoplasmic 3H-noradrenaline concentration is very low (intact vesicular uptake, intact MAO), a 'mobilization' of vesicular 3H-noradrenaline is a prerequisite for substantial release.

The functional coupling of neuronal and extraneuronal transport with intracellular monoamine oxidase.

"Metabolizing systems" are responsible for the quick inactivation of noradrenaline released from adrenergic nerve endings: a transport mechanism (uptake1 or uptake2) is arranged in series with the intracellular enzyme (monoamine oxidase, MAO; catechol-O-methyltransferase, COMT). In the perfused rat heart, kenzyme-values were determined, i.e., those rate constants which characterize the unsaturated intracellular enzymes. In the extraneuronal metabolizing system kcomt greater than kmao for noradrenaline and adrenaline, while rather similar rate constants were obtained for dopamine. However, for the neuronal deaminating system, kmao is considerably higher than kmao for the extraneuronal system. Second, in the rat vas deferens it is demonstrated that inhibition of neuronal MAO leads to very pronounced rises of the axoplasmic noradrenaline concentration--and this is again a reflection of the high activity of neuronal MAO. In a third series of experiments (with the rat vas deferens), the evidence indicates that the neuronal inward transport of substrates of MAO fails to saturate the enzyme. This is the functional consequence of the high activity of neuronal MAO. It is concluded that a) neuronal MAO activity is very high, and--as a consequence--b) axoplasmic noradrenaline levels are very low.

Neuronal efflux of noradrenaline induced by tris or lithium as substitutes for extracellular sodium.

Vasa deferentia of either untreated or reserpine (R) and/or pargyline (P) pretreated rats were incubated with 3H-noradrenaline and then washed with amine- and Ca2+-free solution until (after 100 min) the efflux of radioactivity largely originated from adrenergic nerve endings; COMT was inhibited by U-0521 (U). After 110 min of wash out, the sodium chloride in the wash-out solution was replaced by an equimolar concentration of either Tris-HCl or LiCl. This caused a desipramine-sensitive (i.e., carrier-mediated) efflux of tritiated noradrenaline. The initial increase of the "low Na+"-induced efflux dependent on the experimental conditions: it was most pronounced when the axoplasmic concentration of noradrenaline was high (RPU) and relatively small when MAO and vesicular storage were intact (U). The effects of Li+ and Tris+ differed with regard to the time course of the efflux of tritium: under all three experimental conditions (RPU, PU, U), Tris+ caused the rate of efflux of tritium to increase gradually within the 30 min period of observation, while Li+ either had a "peak-effect" (RPU, PU) or a "plateau-effect" (U). Under "U-conditions" Tris+ caused a slowly increasing, pronounced increase with time of the efflux of both, 3H-noradrenaline and 3H-DOPEG; whereas Li+ caused only a small and sustained increase of the efflux of 3H-noradrenaline and a decrease in the efflux of 3H-DOPEG.(ABSTRACT TRUNCATED AT 250 WORDS)

Time-response curves for barium and noradrenaline in vas deferens of castrated rat.

Time-response curves for barium chloride and noradrenaline were obtained in the isolated vas deferens of 30-day castrated rats. The contractions induced by a maximal dose of barium chloride reached a peak after about 20-30 sec and then decreased to a lower level (fade). 5 min after drug addition the response had faded to about 20% of the peak contraction while in normal preparations it decreased to about 55%. When calcium was removed from the nutrient solution, both peak and 5-min effects of sequential doses were reduced, and fell progressively at a faster rate than in normal preparations. When Ca2+ concentration was increased from 1.8 mM up to 36.0 mM, fading was abolished. The data were analyzed on the basis of receptor changes involving the translocation of calcium in smooth muscle.