Steroidal feedback on photoperiodic induction of testicular growth and development in two bird species.

Present study was performed to demonstrate the effect of exogenous administration of testosterone propionate on photoperiodic induction of testicular growth and development in brahminy myna (Sturnus pagodarum) and baya weaver (Ploceus philippinus). Two groups of brahminy myna and baya weaver (n=5 each) were exposed to15L:9D (group-I) and 9L:15D (group-II), and received 30 µg of TP bird-1 for 15 days. Then, the photoperiod was reversed; the one receiving15L was exposed to 9L and vice versa. Observations on body mass and testis volume were taken at the beginning and at 15 days interval. In brahminy myna, a significant change in body mass occurred under 9L:15D, transfer to 15L:9D, but not under 15L:9D group, transfer to 9L:15D. Also, testes were stimulated under 15L:9D transferred to 9L:15D, but not under 9L:15D transferred to 15L:9D. In baya weaver, body mass increased under 15L:9D and 9L:15D for first 15 days and was maintained until the end of the experiment. Testes enlarged gradually in both groups (15L:9D and 9L:15D transfer to vice versa), but it regressed in 15L:9D group, transferred to 9L:15D after 45 days. Taken together it appears that body mass response indicates the photoperiodic effect and gonadal response indicates the hormonal effect. Finally results conclude that the photoperiod and circulating testosterone levels feedback on to hypothalamus regulates reproductive cycle in these birds.

Response to complete and skeleton photoperiods in subtropical male house sparrow, Passer domesticus (Linnaeus).

To examine the importance of the inductive light period of a skeleton photoperiod in relation to the endogenous circadian rhythm of photoinducibility mediating photoperiodic induction, P. domesticus were exposed for 28 weeks to a series of skeleton photoperiods, viz. 6L:4D:1L:13D, 6L:6D:1L:11D. 6L:8D:1L:9D and 6L:14D:1L:3D. The inductive effects of 1 hr light pulse at night varied depending on the time of its placement. To compare the inductive effects of complete and its corresponding skeleton photoperiods, birds in the second experiment were subjected for 20 weeks to 12L:12D and 6L:5D:1L:12D given daily or interposed on alternate days with constant darkness (12L:12D/DD and 6L:5D:1L:12D/DD). There was a difference in the rate and magnitude of response between the complete and skeleton photoperiods. It appears that the subtropical house sparrow uses photoperiodic strategy in regulation of its seasonal testicular responses similar to that is reported for its temperate population.

Effect of a composite Indian herbal preparation, CIHP(III) on avoidance learning during endurance performance of rats.

A nine week cross over study (5 weeks drug administration and 4 weeks withdrawal) was performed to see the effect of a composite Indian herbal preparation (CIHP III), viz. Mentat, on avoidance learning during endurance performance of albino rats. Runimex, a circular runway was used for this purpose. The number of stimuli viz. electrical shock of 10 mv, in drug treated rats at an oral dose of 47.86 mg/100 g body wt/single dose/day for 5 days were significantly reduced as compared to rats not taking any drug. The number of stimuli decreased significantly when the drug was started in the control group. No change in avoidance learning was observed over the period of 9 weeks in another group of rats. Results indicate significant improvement in avoidance learning during endurance performance due to the intake of CIHP(III).

Effect of age on susceptibility of carcinogen benzidine-hydrochloride.

Susceptibility of carcinogen (benzidine hydrochloride) was checked by degranulation technique in rats of three different (young, adult and old) age groups. The dose response curves of these three different groups showed different per cent degranulation. Comparative data of dose response of benzidine hydrochloride observed on the basis of RNA/Protein ratio basis showed that old animals were more susceptible to carcinogens than young and adult animals.