Effect of methomyl formulation, a carbamate pesticide on ovarian follicular development and fertility in albino mice.

Administration of 5 mg methomyl (40%) kg-1 b.wt. mouse-1 (equal to 50% of LD50 dose), every day for 90 days to adult female mice resulted in a significant decrease in body weight, relative weight of the ovary, uterus and fallopian tube; mean number of small, preantral, antral and pre-ovulatory follicles and fertility compared to controls. On the other hand, total duration of the estrous cycle was significantly increased compared to controls. One month after the cessation of the treatment (a commercial methomyl preparation-lannate) the effect on estrous cycle and organ weight was not restored. Treatment of 2.5 mg or 1 mg lannate kg-1 b. wt., although did not alter duration of the estrous cycle; relative weight of the ovary, uterus, and fallopian tube and fertility, caused a significant decrease in mean number of small follicles compared to controls. All the groups of mice treated with lannate showed loss in body weight (15.15% in 1 mg, 6.61% in 2 mg and 12.16% in 5 mg treated groups) whereas controls showed a gain in body weight (20.02%) during the period of experimentation. The results indicate that 5 mg lannate kg-1 b. wt. causes loss of follicles and infertility, whereas lower dosages (2.5 and 1 mg) reduce the number of small follicles which might shorten reproductive life span of mice.

Progesterone prevents corticosterone mediated inhibition of estrous behaviour in rats.

Stress induced by application of electric foot shocks (300 μA/shock, five shocks per episode, 4 episodes at 1800, 1830, 1900 and 1930 hrs on the proestrus day) to rats at the time of pre-ovulatory progesterone secretion, abolished lordosis and resulted in maximum rejection co-efficient, whereas treatment with a CRF receptor antagonist (α -helical CRF9-41) or metapirone, an inhibitor of corticosterone synthesis, prior to application of the electric foot shocks, resulted in normal lordosis and a significant reduction in rejection coefficient. Further, administration of a single dose of corticosterone (40 μg) at 1800 hrs of proestrus caused inhibition of lordosis and resulted in maximum rejection co-efficient. On the other hand, corticosterone + progesterone treatment at 1800 hrs of proestrus resulted in normal lordosis and a significant reduction in rejection coefficient. The facts that stress induced inhibition of lordosis is prevented by CRF receptor antagonist or metapirone and that corticosterone inhibits lordosis indicate that stress induced inhibition of lordosis is mediated by corticosterone. Further, normal display of lordosis by rats treated with corticosterone + progesterone in contrast to its absence in corticosterone alone treated rats suggests that impaired progesterone secretion due to action of corticosterone leads to inhibition of lordosis.

Concentration of cations in different parts of male reproductive system and their influence on in vitro sperm motility in lizard, Mabuya carinata Schneider.

Concentrations of mono- and divalent cations in the testis, three different regions of the epididymis and the vas deferens of lizard, M. carinata were determined. The concentrations of Na+, K+ and Ca2+ increased gradually from testis to vas deferens. However, no significant variation in the levels of Mg2+ was observed between testis and anterior epididymis, and between posterior epididymis and vas deferens. Further, in an in vitro sperm motility study, wherein different concentrations of the cations were tested, the maximum forward progressive motility of posterior epididymal spermatozoa was observed following treatment with 140 mMNaCl, 25 mM KCl, and 50 mM CaCl2 whereas, treatment with magnesium brought about a decrease in sperm motility. The results indicate that Na+, K+, and Ca2+ have stimulatory effect at an optimum dose, whereas Mg2+ has an inhibitory effect even at very low concentration, on sperm motility in the lizard M carinata.

A study on physicochemical parameters of an aquaculture body in Mysore city, Karnataka, India.

Monthly changes in water quality parameters (physicochemical) of a rain fed lake (Bilikere) in Mysore city, were investigated for two calendar years (2002 and 2003) to assess the suitability of this lake for pisciculture. Although there were monthly fluctuations in water temperature, total suspended solids (TSS), dissolved oxygen (DO), nitrite and ammonia, they were within the desirable limits. On the other hand, total alkalinity and hydrogen sulphide throughout the study period and pH for a major part, were higher than the desirable limits. Other parameters viz; turbidity, biological oxygen demand (BOD), phosphate, and nitrate in a few months were higher than the desirable limits for waters used for fish culture. The high levels of these factors are due to the entry of agricultural run off and occasional flow of sewage into the lake. In addition dense algal growth was noticed at times of the year which is caused by surge in nutrients level whenever there was a rainfall. Since, the lake has a great aquacultural potential, it is suggested that control of nutrient load that enters the lake occasionally, might help the lake to continue its mesotrophic status.

Progesterone restores stress induced inhibition of estrous behavior in rat.

Exposure to a stressor (mild electrical shocks to foot, five times per episode, at 1800, 1830, 1900 and 1930 hrs of proestrus) coinciding with period of pre-ovulatory progesterone secretion in rats abolished estrous behavior as shown by the absence of lordosis response and a significant increase in rejection quotient compared to controls. These rats did not show spermatozoa in the vaginal smear next day morning in contrast to their presence in controls. On the other hand, rats treated with progesterone (a single injection, 500 microg in 0.1 ml olive oil at 1800 hr of proestrus) prior to exposure to stressor showed normal estrous behavior, as shown by significantly lower rejection quotient than rats exposed to stress alone, lordosis quotient similar to controls and presence of spermatozoa in the vaginal smear next day. The results, albeit indirectly, to the best of our knowledge, first time indicate that stress induced impaired steroidogenesis leads to suppression of estrous behavior.

Influence of gonadotropins on adrenalectomy induced changes in the testis of albino mouse.

Effects of adrenalectomy and administration of gonadotropins on cell counts of different cell types of spermatogenesis and morphology of the Leydig cells were studied in 30 day old mice. Adrenalectomy (duration, 12 days; age at autopsy 42 days) caused a significant decrease in the diameters of seminiferous tubules and Leydig cell nucleus and, cell counts of intermediate spermatogonia, round and elongated spermatids. Administration of FSH (75 micrograms/0.1 ml saline) + LH (25 micrograms/0.1 ml saline) everyday for 12 days to adrenalectomized mice restored testicular activity as revealed by significant increases in mean diameter of the Leydig cell nuclei and cell counts of intermediate spermatogonia and elongated spermatids over those of adrenalectomized mice. The results indicate that (i) testis of adrenalectomized mouse responds to gonadotropin treatment and (ii) impairment in gonadotropin secretion is possibly a major factor in inducing testicular regression following adrenalectomy.

LHRH induced changes in the interrenal gland of the frog Rana cyanophlyctis (Schn.).

Administration (i.m.) of synthetic mammalian LHRH (40 ng/frog, alternate day for 30 days) to adult male intact frogs R. cyanophlyctis resulted in activation of the interrenal cells as shown by increases in nuclear diameters of the interrenal cells, activity (histochemical demonstration) of delta 5-3 beta-hydroxysteroid dehydrogenase and glucose-6-phosphate dehydrogenase and concomitant decrease in sudanophilic lipid droplets in the interrenal gland when compared to those of controls. These changes were not observed in the interrenal gland of LHRH treated hypophysectomized frogs. The results indicate that LHRH stimulates secretory activity of the interrenal cells and action may not be directly on the adrenal gland.