Circadian Rhythms in Reproductive and Thyroid Hormones in Gonadally Regressed Male Hamsters Exposed to Natural Autumn Photoperiod and Temperature Conditions

Vaughan, Mary K.; Menéndez-Peláez, Armando; Buzzell, Gerald R.; Vaughan, George M.; Little, John C.; Reíter, Russel J.

doi:10.1159/000126725

Cited by 11 publications

(8 citation statements)

References 17 publications

(29 reference statements)

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“…The present results concerni n g a v i a n t e s t e s c l e a r l y d e m o n s t r a t e d n o spermatogenesis in seminiferous tubules in the treatment group compared with the control group. This finding is similar to that in other animals, such as in male rats [29,30], male guinea pigs [31] and male hamsters [32][33][34]. In rats, previous reports have demonstrated that hypothyroidism inhibits steroidogenesis [29,30].…”

Section: Discussionsupporting

confidence: 90%

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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Section: Discussionsupporting

confidence: 90%

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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“…Localization of haPer1 and/ or PER1 protein to particular cell types in hamster testis may help to explain apparent species differences and suggest a physiological role of period gene expression in testicular function. Syrian hamsters exhibit significant (twofold) daily rhythms of testosterone secretion (Vaughan et al, 1994), whereas the expression of such rhythms in mice varies with strain (Lucas and Eleftheriou, 1980). Despite the fact that Per1 expression is concentrated in the seminiferous tubules rather than the interstitial tissue, it may be functionally related to androgen production.…”

Section: Discussionmentioning

confidence: 99%

Expression of haPer1 and haBmal1 in Syrian Hamsters: Heterogeneity of Transcripts and Oscillations in the Periphery

et al. 2004

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The molecular biology of circadian rhythms has been extensively studied in mice, and the widespread expression of canonical circadian clock genes in peripheral organs is well established in this species. In contrast, much less information about the peripheral expression of haPer1, haPer2, and haBmal1 is available in Syrian hamsters despite the fact that this species is widely used for studies of circadian organization and photoperiodic responses. Furthermore, examination of oscillating expression of these genes in mouse testis has generated discrepant results, and little is known about gonadal expression of haPer1 and haBmal1 or their environmental control. To address these questions, the authors examined the pattern of haPer1 and haBmal1 in heart, kidney, liver, muscle, spleen, and testis of hamsters exposed to DD. In most organs, Northern blots suggested the existence of single transcripts of each of these messenger RNAs (mRNAs). haPer1 peaked in late subjective day and haBmal1 during the late subjective night. Closer inspection of SCN and muscle haPer1, however, revealed the existence of two major transcripts of similar size, as well as minor transcripts that varied in the 3′-untranslated region. In hamster testis, two haPer1 transcripts were found, both of which are truncated relative to the corresponding mouse transcript and both of which contain a sequence homologous to intron 18 of mPer1. Neither testis transcript contains a nuclear localization signal, and haPer1 transcripts lacked the putative C-terminal CRY1-binding domain. Furthermore, the testis deviated from the general pattern in that haPer1 and haBmal1 both peaked in the subjective night. In situ hybridization revealed that haPer1, but not haBmal1, showed a heterogeneous distribution among seminiferous tubules. Hamster testis also expresses 2 haPer2 transcripts, but no circadian variation is evident. In a second experiment, long-term exposure to DD sufficient to induce gonadal regression was found to eliminate circadian oscillations of both testicular haPer1 transcripts. In contrast, gonadal regression was accompanied by a more robust rhythm of haBmal1.

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“…De fato, foram medidas, no início do período claro concentrações mais altas do que no início do período escuro, o que sugere um ciclo circadiano de variação da concentração sanguínea de testosterona com acrofase 12 horas antes, ou seja, no início da noite. Este resultado está de pleno acordo com o ritmo circadiano da produção de testosterona relatado na literatura para o hamster macho (Vaughan et al 1994). Na mesma espécie, prazos de 5 a 25 horas foram relatados para metabolização e excreção de esteróides ovarianos (Chelini et al 2005) e de 20 horas para o aparecimento nas fezes dos machos do sinal da elevação dos níveis de glicocorticóides em resposta a um desafio por ACTH (Chelini et al 2010).…”

Section: Discussionunclassified

Validação de um radioimunoensaio para a quantificação de metabólitos fecais de testosterona em hamster Sírio (Mesocricetus auratus)

2011

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Modelo para o estudo de diversas doenças humanas, o hamster tem sido objeto de numerosos estudos comportamentais e envolvendo estresse e/ou comportamento agonístico que supõem, muitas vezes, o monitoramento das flutuações hormonais nos indivíduos envolvidos. O objetivo do presente trabalho foi confirmar a adequação de um conjunto comercial para dosagem de testosterona em sangue humano para a quantificação de metabólitos fecais de testosterona (MFT) em hamsters Sírios machos e fêmeas. Dez machos foram submetidos a um desafio com um agonista de GnRH para estimular a atividade testicular, elevando os níveis circulantes de testosterona. Cinco fêmeas receberam uma injeção de testosterona enquanto cinco outras receberam uma injeção de solução salina. Amostras de fezes coletadas antes e depois dos procedimentos, assim como amostras fecais de 20 fêmeas gestantes coletadas ao longo da gestação foram analisadas com um conjunto comercial para radioimunoensaio. Um pico de MFT 12h após a injeção seguido de uma queda abaixo do nível basal comprovou que, nos machos, as alterações nos níveis de MFT refletem as alterações da concentração de testosterona no sangue. Nestes observou-se um ciclo circadiano das concentrações de MFT com acrofase no início do período claro correspondendo ao ciclo descrito para as concentrações sanguíneas na literatura. Nas fêmeas a administração de testosterona exógena provocou uma elevação importante dos níveis de MFT, mas as concentrações medidas ao longo da gestação não refletiram o padrão dos níveis sanguíneos do hormônio endógeno. O conjunto para radioimunoensaio para testosterona em sangue humano mostrou-se adequado para o monitoramento da função testicular no hamster macho, mas um ensaio mais específico seria necessário para as fêmeas.

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Circadian Rhythms in Reproductive and Thyroid Hormones in Gonadally Regressed Male Hamsters Exposed to Natural Autumn Photoperiod and Temperature Conditions

Cited by 11 publications

References 17 publications

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

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

Expression of haPer1 and haBmal1 in Syrian Hamsters: Heterogeneity of Transcripts and Oscillations in the Periphery

Validação de um radioimunoensaio para a quantificação de metabólitos fecais de testosterona em hamster Sírio (Mesocricetus auratus)

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