The Timing of Thyroid-Dependent Programming in Seasonally Breeding Male American Tree Sparrows (Spizella arborea)

Wilson, Fred E.; Reinert, Bryan D.

doi:10.1006/gcen.1996.0096

Cited by 41 publications

(23 citation statements)

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“…However, some species show seasonal changes in HVC neuron number (Tramontin and Brenowitz, 2000), suggesting that this balance can be altered seasonally in a manner reminiscent of our chronic T 4 effects. Thyroxine may play an important role in the regulation of seasonal breeding (reviewed by Nicholls et al, 1988;Dawson, 1989a,b;Wilson and Reinert, 1996); in canaries, this hormone varies seasonally in register with seasonal changes in neuronal replacement (unpublished observations). Thyroid hormone could play an important role in regulating the normal timing of song learning or song production, both during development and, in some species, seasonally throughout life.…”

Section: Discussionmentioning

confidence: 94%

Effects of excess thyroid hormone on cell death, cell proliferation, and new neuron incorporation in the adult zebra finch telencephalon

Tekumalla¹,

Tontonoz²,

Hesla³

et al. 2002

J. Neurobiol.

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Widespread telencephalic neuronal replacement occurs throughout life in birds. We explored the potential relationship between thyroxine (T4) and cell turnover in the adult male zebra finch. We found that many cells in the zebra finch brain, including long-projection neurons in the high vocal center (HVC), stained positively with an antibody to thyroid hormone receptors (TR). Labeling was generally weak in the ventricular zone (VZ) that gives rise to new neurons but some proliferative VZ cells and/or their progeny, identified by [3H]-thymidine labeling, co-labeled with anti-TR antibody. Acute T4 treatment dramatically increased the number of pyknotic and TUNEL-positive cells in HVC and other telencephalic regions. In contrast, degenerating cells were never observed in the archistriatum or sub-telencephalic regions, suggesting that excess T4 augments cell death selectively in regions that show naturally occurring neuronal turnover. VZ mitotic activity was not altered shortly after acute T4 treatment at a dosage that stimulated cell death, although [3H]-labeling intensity per cell was slightly reduced. Moreover, the incorporation rates for neurons formed shortly before or after acute hormone treatment were no different from control values. Chronic T4 treatment resulted in a reduction in the total number of HVC neurons. Thus, hyperthyroidism augmented neuronal death, which was not compensated for by neuronal replacement. Collectively, these results indicate that excess T4 affects adult neuronal turnover in birds, and raises the possibility that thyroxine plays an important role in the postnatal development of the avian brain and vocal behavior.

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Section: Discussionmentioning

confidence: 94%

Effects of excess thyroid hormone on cell death, cell proliferation, and new neuron incorporation in the adult zebra finch telencephalon

Tekumalla¹,

Tontonoz²,

Hesla³

et al. 2002

J. Neurobiol.

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“…In birds, photoresponses may involve T4 [15,16], since T4 may be necessary to induce and maintain the photorefractory state [9]. However, little information is available on the relationships of T4 to reproduction in male turkeys.…”

Section: Introductionmentioning

confidence: 97%

Effects of Photoperiod and Age on Secretory Patterns of Luteinizing Hormone and Testosterone and Semen Production in Male Domestic Turkeys1

Yang

Long

Inpanbutr

et al. 1998

Biology of Reproduction

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The objective of this study was to determine effects of photoperiod and age on the circulating concentrations of LH, testosterone (T), thyroxine (T4), and semen production in male turkeys. Male turkeys from 10 or 12 wk of age were maintained under either a long-day (LD) photoperiod of 16L:8D up to 35 wk (LL), or a short-day (SD) photoperiod of 6L:18D to 29 wk and then an LD photoperiod of 16L:8D up to 35 wk of age (SL). Plasma concentrations of both LH and T increased by 17 or 18 wk of age under both photoperiods, but higher levels were attained in the LL group prior to 29 wk of age. Both LH and T levels increased significantly within days in the SL group after the group was switched to LD at 29 wk of age. Higher levels of T4 were present in the LL group prior to sexual maturation. No differences were observed in T4 concentration between lighting treatments after sexual maturation. The LL group first produced semen at 20-22 wk of age, which was about 1 wk earlier than first semen production in the SL group. A significantly larger volume of semen was produced in the LL group at most ages. No further increase in semen production was observed in the first 6 wk after the SL group was switched to the LD photoperiod at 29 wk of age. Pulsatile patterns of LH and T were characterized by serial blood sampling at 13, 23, and 35 wk of age under both the LL and SL photoperiods. The baseline levels of both LH and T in male turkeys were influenced by age and photoperiod. However, pulse characteristics (numbers, duration, and amplitude) of LH did not change with age or lighting treatment, while pulse characteristics of T did change with age. We conclude that exposing male turkeys to an LD photoperiod from 10 or 12 wk of age advanced the age of sexual maturation and induced earlier increased concentrations of LH and T.

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“…Other studies in birds support the hypothesis that the thyroid axis plays a permissive role in the reproduction of seasonally breeding species [11][12][13]. Therefore, the aim of this study was to investigate the effects of hypothyroidism on the adrenal and gonadal functions in adult male Japanese quail.…”

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confidence: 93%

Effect of Methimazole-induced Hypothyroidism on Adrenal and Gonadal Functions in Male Japanese Quail (<i>Coturnix japonica</i>)

Wang

Saita

Watanabe

et al. 2007

Journal of Reproduction and Development

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Abstract.To investigate the effect of hypothyroidism on gonadal and adrenal functions in male Japanese quail (Coturnix japonica), hypothyroidism was induced in male adult Japanese quail by daily administration of 2-Mercapto-1-methylimidazole (methimazole) in their drinking water. Four weeks after methimazole treatment, the Japanese quail were scarificed, and the plasma concentrations of free triiodothyronine (FT3), free thyroxine (FT4), total T3 (TT3), total T4 (TT4), corticosterone, testosterone, LH and immunoreactive (ir) inhibins were measured by radioimmunoassy, the testes and adrenal glands were removed and weighed and the thyroid glands and testes were fixed in 4% paraformaldehyde for histological observation. The results showed that the hypothyroidism induced by methimazole caused a significant decrease in body and testes weight; the plasma levels of FT3, FT4 and TT4 significantly decreased, and the hypothyroid quail possessed a greater number of small follicles and more follicular epithelial cells in the thyroid gland. In addition, hypothyroidism resulted in a significant decrease in the plasma concentrations of corticosterone, LH, testosterone and irinhibin. Furthermore, no spermatogenesis was found in the seminiferous tubules of the methimazole treatment groups. These results clearly demonstrate that hypothyroidism caused both gonadal and adrenal disturbances in the adult male Japanese quail.

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The Timing of Thyroid-Dependent Programming in Seasonally Breeding Male American Tree Sparrows (Spizella arborea)

Cited by 41 publications

References 0 publications

Effects of excess thyroid hormone on cell death, cell proliferation, and new neuron incorporation in the adult zebra finch telencephalon

Effects of excess thyroid hormone on cell death, cell proliferation, and new neuron incorporation in the adult zebra finch telencephalon

Effects of Photoperiod and Age on Secretory Patterns of Luteinizing Hormone and Testosterone and Semen Production in Male Domestic Turkeys1

Effect of Methimazole-induced Hypothyroidism on Adrenal and Gonadal Functions in Male Japanese Quail (<i>Coturnix japonica</i>)

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