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Journal ArticleDOI

Suppression of annual testicular development in Indian Palm Squirrel, Funambulus pennanti by 8 hr temporal relationship of serotonin and dopamine precursor drugs

01 Jan 1992-Journal of Neural Transmission (Springer Verlag)-Vol. 88, Iss: 1, pp 53-60
TL;DR: Results indicate that induced suppression of gonadal function in a fashion similar to seasonal regression leading to non-breeding condition is the consequence of specific phase relationship (8 hr) between serotonergic and dopaminergic activities and not due to Serotonin or dopamine alone.
Abstract: Daily injections of 5-HTP (5-hydroxytryptophan, serotonin precursor) and L-DOPA (L-Dihydroxyphenylalanine, dopamine precursor) given 8 hour apart inhibited normal testicular growth in seasonally breeding Indian Palm Squirrel,Funambuluspennanti leading to complete gonadal atrophy, which was maintained till the end of the study. HCG administration induced higher degree of gonadal development but, when the two treatments (HCG + 8 hr relationship of 5-HTP and L-DOPA) were given simultaneously no significant difference was observed compared to control.
Citations
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Journal ArticleDOI
TL;DR: Findings not only suggest the modulation of gonadal development in mice by changing the temporal phase relation of serotonergic and dopaminergic oscillations, but also demonstrate an inverse correlation of RFRP-3 neurons and gonadal activity in both control and experimental conditions.
Abstract: In order to study the effect of the temporal synergism of neural oscillations on reproductive regulation and the response of RFamide-related peptide-3 (RFRP-3; a mammalian ortholog of avian gonadotropin-inhibitory hormone), expression of immunoreactive RFRP-3 in the neurons of the dorsomedial nucleus of the hypothalamus was monitored in sexually immature and mature laboratory mice (study I). In study II, the effects of serotonin and dopamine precursors (5-hydroxytryptophan and L-dihydroxyphenylalanine; injected daily, 8 or 12 h apart, for 13 days in 3-week-old mice) on testicular activity and immunoreactive RFRP-3 neurons were studied until 24 days after treatment. Results indicate high levels of expression of immunoreactive RFRP-3 in the sexually immature and 8-hour mice (simulating gonadal suppression), while a low level was noted in mature and 12-hour mice (simulating gonadal stimulation). These findings not only suggest the modulation of gonadal development in mice (during the course of puberty attainment) by changing the temporal phase relation of serotonergic and dopaminergic oscillations (as in some seasonally breeding species), but also demonstrate an inverse correlation of RFRP-3 neurons and gonadal activity in both control and experimental conditions.

23 citations


Cites background from "Suppression of annual testicular de..."

  • ...On the other hand, in this subtropical mammalian species, an 8-hour phase relation stimulates non-breeding conditions out of season [...

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Journal ArticleDOI
01 Nov 2009-Zoology
TL;DR: It is concluded that normal somatic and gonadal growth of pre-puberal mice may be suppressed with an 8-hr phase relation of circadian serotonergic and dopaminergic oscillations, which accelerated the rate of gonadal maturation and led to more or less similar gonadal development as in the control mice.

19 citations

Journal ArticleDOI
TL;DR: The findings suggest that the temporal phase relation of circadian serotonergic and dopaminergic oscillator varies as a function of reproductive status of the bird, and breeding/non-breeding conditions may be induced experimentally by changing the phase relationof these oscillations.
Abstract: Temporal phase relations of circadian hypothalamic neurotransmitters are reported to regulate seasonal reproduction in some avian species. Present experiments were designed to study circadian variation in the hypothalamic concentration of neurotransmitters (serotonin and dopamine) and the plasma thyroxine level in sexually active (long day) and inactive (short day) Japanese Quail. A significant circadian cycle was noted in the hypothalamic content of both serotonin and dopamine, but with different patterns. In breeding Quail, peak activity of serotonin and dopamine was noted at 10.00 A.M. and 10.00 P.M. respectively i.e. at the interval of 12 hours. However, during sexually quiescent condition, peaks of both neurotransmitters occurred at 2.00 P.M. i.e. having a 0-hour temporal relationship. During the breeding phase, the plasma thyroxine level showed a biphasic pattern with two circadian peaks at 10.00 A.M. and 10.00 P.M. whereas in the non-breeding condition a single peak was observed at 10.00 A...

16 citations


Cites background from "Suppression of annual testicular de..."

  • ...Hamster (Wilson & Meier 1988), Indian palm squirrel (Chaturvedi & Jaiwal 1990; Jaiwal & Chaturvedi 1991; Chaturvedi & Singh 1992) and in Killfish (Emata et al. 1985)....

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Journal ArticleDOI
TL;DR: It is suggested that administration of 5‐HTP and L‐DOPA at specific time interval and variation in pineal functions that modulate reproductive responses also alter the circadian pattern (acrophase and amplitude) of hypothalamic serotonin and dopamine, maintaining a specific phase relation between these cycles and breeding status.
Abstract: In this study, hypo‐ and hyper‐reproductive conditions, as measured by concentrations of plasma testosterone in male Japanese quail held on long days LD 16:8, were experimentally simulated with injections of 5‐hydroxytryptophan (5‐HTP) and L‐dihydroxyphenylalanine, (L‐DOPA) with 8 h and 12 h phase angle differences between them in intact and melatonin‐treated birds. The effects of these treatments were assessed on the characteristics of the circadian rhythm in the hypothalamic concentration of serotonin (5‐HT), dopamine (DA), and plasma levels of thyroxine (T4), triiodothyronine (T3), and testosterone (T). These rhythms were also studied in sham‐operated (SO), pinealectomized (Px), vehicle‐ (Veh), and melatonin (Mel)‐treated birds. On the basis of the circadian mesors of the testosterone rhythms, three distinct categories could be identified: category A (i.e., normal breeding concentrations of plasma testosterone), which includes control, sham‐operated, and vehicle‐treated groups; category A+ (i.e., conce...

11 citations

Journal ArticleDOI
TL;DR: Results are in agreement with the internal coincidence model of photoperiodic time measurement and indicate that birds can detect specific phase relationship between the two neural oscillations for their reproductive regulations and circadian organization is intricately involved in the regulation of seasonality.

8 citations


Cites background from "Suppression of annual testicular de..."

  • ...…discussed for birds has been reported to modulate the gonadal development of seasonally breeding mammalian species Syrian hamster (Wilson and Meier, 1989), Indian palm squirrel (Chaturvedi and Jaiwal, 1990; Chaturvedi and Singh, 1992; Jaiwal and Chaturvedi, 1991) as well as laboratory mouse....

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  • ...The protocol discussed for birds has been reported to modulate the gonadal development of seasonally breeding mammalian species Syrian hamster (Wilson and Meier, 1989), Indian palm squirrel (Chaturvedi and Jaiwal, 1990; Chaturvedi and Singh, 1992; Jaiwal and Chaturvedi, 1991) as well as laboratory mouse....

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References
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Journal ArticleDOI
TL;DR: By the usual criteria in endocrinology, the pineal now fulfills all the qualifications of an organ of internal secretion.
Abstract: ONLY A LITTLE over a decade ago, any discussion of the function of the pineal gland included qualifying adjectives such as alleged, supposed, and putative. In the same vein, since it connoted a hormonal function, rather than referring to the pineal as a gland, the phrase pineal organ was usually employed to describe this portion of the epithalamus. However, this is no longer the case, at least in mammals. By the usual criteria in endocrinology, the pineal now fulfills all the qualifications of an organ of internal secretion. Several major discoveries revolutionized ideas concerning the function of the pineal gland. Certainly, as noted frequently in other reviews, the isolation and identification of N-acetyl-5-methoxytryptamine (melatonin), a pineal hormone, from bovine pineal tissue by Lerner et al. (1, 2) provided a strong impetus for subsequent investigations on this sometimes exasperating organ. At least as important as this discovery, however, were the observations that light and darkness govern both ...

1,229 citations


"Suppression of annual testicular de..." refers background in this paper

  • ...Although much attention has been paid to study the mechanism underlying seasonality in temperate zone mammals (Reiter, 1981; Stetson etal., 1984) studies are scanty in subtropical species....

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Journal ArticleDOI
TL;DR: The ability of the 5‐ HT neurons to take up and accumulate 5‐HT in the presence of5‐HTP is relatively low in spite of large amounts of 5-HTP present in the brain neuropil after extracerebral decarboxylase inhibition.
Abstract: The histochemical effects of 500 and 1000 mg/kg of dl-5-hydroxy-tryptophan (5-HTP), both alone and in combination with a peripheral decarboxylase inhibitor (seryl-trihydroxy benzyl hydrazine; Ro 4–4602) have been examined on central monoamine neurons of rats by the Falck-Hillarp fluorescence technique that demonstrates monoamines and their precursors. 5-HTP alone or together with Ro 4–4602 caused only weak intraneuronal accumulation of 5-HT in the central 5-HT neurons, in spite of an increased entry of 5-HTP into the brain after Ro 4–4602 treatment, as shown by an increase in the specific neuropil fluorescence and a reduction of 5-HT accumulation in the cells of the capillary walls. Ro 4–4602 markedly potentiated the effects of 5-HTP on the central dopamine neurons, many of which became clearly yellow fluorescent. The mechanism of dopamine depletion by 5-HTP is probably therefore mainly one of displacement. The effects on the noradrenaline neurons were also potentiated by Ro 4–4602 pretreatment, the neurons exhibiting a yellow-green fluorescence. This depletion may therefore also be mainly be due to amine displacement. It is concluded that the ability of the 5-HT neurons to take up and accumulate 5-HT in the presence of 5-HTP is relatively low in spite of large amounts of 5-HTP present in the brain neuropil after extracerebral decarboxylase inhibition.

156 citations


"Suppression of annual testicular de..." refers background in this paper

  • ...These doses of neurotransmitter precursors are reported to increase brain content of Serotonin (Fuxe et al., 1971; Bobillier etal., 1975; Korf et al., 1974) and Dopamine (Shindo etal., 1973; Jimenez et al., 1978) respectively in rats....

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  • ...Results indicate that induced suppression of gonadal function in a fashion similar to seasonal regression leading to non-breeding condition is the consequence of specific phase relationship (8 hr) between serotonergic and dopaminergic activities and not due to Serotonin or dopamine alone....

    [...]

  • ...These doses of neurotransmitter precursors are reported to increase brain content of Serotonin (Fuxe et al., 1971; Bobillier etal., 1975; Korf et al., 1974) and Dopamine (Shindo etal....

    [...]

  • ...Daily injections of 5-HTP (Serotonin precursor) and L-DOPA (Dopamine precursor) in specific temporal relationship has been reported to convert scotosensitive (reproductivity inhibited by short daylengths) hamsters to scotorefractory condition and vice-versa (Wilson and Meier, 1989)....

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Journal ArticleDOI
TL;DR: The results suggest that some relationships occurred between the changes in 5-HT SYNTHESIs and release after the first hour of perfusion and the absence of effects of tryptophan treatments on 5- HT release during the firsthour of perfusions are discussed.

85 citations