Showing papers by "Chandra Mohini Chaturvedi published in 2003"

Effect of temporal synergism of neural oscillators on gonadal development, egg production and hatchability of Japanese quail (Coturnix coturnix japonica)

Abstract: To study the effect of temporal synergism of neural oscillators (serotonergic and dopaminergic) on gonadal development, egg production and hatchability, three weeks old sexually immature Japanese quail were divided into three groups. First group quail received two daily injections of normal saline (control), second group quail received serotonin precursor (5-Hydroxytryptophan-5-HTP, 5 mg/100gm body weight) at 5.00 A.M. and dopamine precursor (L-dihydroxyphenylalanine-L-DOPA, 5mg/l00gm body weight) at 1.00 P.M. (8-hr) and third group quail received above two injections at the interval of 12 hour i.e. at 5.00 A.M. and 5.00 P.M. respectively (12-hr). Each group contained colony of male and female quail (1:2 ratio). After 11 days of treatment, given in continuous condition of light (LL), quail were transferred to long day length condition (LD 16:8) and biweekly observations were taken. The 12-hr quail showed significant increase in the rate and degree of development of cloacal gland and testicular size, whereas in 8-hr group suppression of reproductive development was seen compared to control. Female quail also showed similar trend in follicular diameter and ovarian weight. Onset of egg laying was observed by 5th week in 12-hr quail, by 7th week in control and no egg laying was noted in 8-hr quail. Moreover, rate of egg production, egg size and hatchability rate was remarkably high in 12-hr quail compared to control. It is obvious that 12-hr relation induced precocious sexual maturity and increased the rate of tertility. These observations suggest that injections of serotonergic and dopaminergic precursor drugs (5-HTP and L-DOPA) given at specific time interval had significant intluence on the maturation of neuroendocrine gonadal axis as well as rate of reproduction.

Regulation of seasonal reproduction by neurotransmitter affecting drugs in spotted munia, Lonchura punctulata

Abstract: Timed daily injection of serotonin precursor, 5-HTP (5-Hydroxytryotophan) and dopamine precursor, L-DOPA (Dihydroxyphenylalanine) determine seasonality in wild finch spotted munia. Lonchura punctulata, which does not utilize photoperiod to tune their seasonal reproduction. These effects are due to serotonergic and dopanunergic activities and not due to serotomn and dopamine alone. Further, L-DOPA was effective when converted into dopamine and not into nor-adrenaline or adrenaline, the next biosynthetic product of dopamine. The findings suggest that seasonal changes in the reproductive functions may be related to seasonal changes in the phase relationship between daily rhythms in serotonergic and dopaininergic activity in the central nervous system.

In ovo administration of sex steroids alters vasotocin synthesis in bed nucleus of stria terminalis in female chicken

Abstract: The present study was performed to check the effect of in ovo administration of sex steroids on expression of arginine vasotocin (AVT) gene in a sexually dimorphic hypothalamic nucleus, the bed nucleus of stria terminalis(BnST) in chicken. Sex steroids (estradiol benzoate/testosterone propionate; 20 μg/egg) were administered at embryonic day 6 (E 6 ) and embryonic brains were processed for localization of AVT mRNA and immuno reactive (ir)-AVT by in situ hybridization and immunohistochemistry at E 1 8 , D 7 , D 2 1 and D 4 0 . Our results indicate that in ovo administration of sex steroids can increase the steady-state level of AVT mRNA in BnST. Sex-steroid administration upregulated the expression/synthesis of AVT transcript/ir-AVT throughout the stages of development studied. In the testosterone propionate-treated group, few neurons showing ir-AVT in BnST were observed at D 2 1 and D 4 0 post-hatch. It is obvious that expression of AVT gene in BnST which is related with reproductive behaviour, may be altered following administration of sex steroids in the egg during development (E6). It is suggested that single injection (in ovo) of sex hormone during early embryonic stage(s) may modulate vasotocinergic neurons and expression of AVT gene in the developing brain of chicken. Further, administration of sex steroids appears to have an irreversible and long-lasting effect on AVT neurons of sexually dimorphic BnST nuclei, an effect similar to that of sex hormones in mammals during the critical period of differentiation of the brain into male or female type.