Circulating LH and FSH Levels and Testicular Function in Hamsters During Light Deprivation and Subsequent Photoperiodic Stimulation1

Berndtson, W. E.; Desjardins, Claude

doi:10.1210/endo-95-1-195

Cited by 245 publications

(108 citation statements)

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“…However, another consideration is that the control mechanisms are not different at all but that for some unexplained reason the endocrine dynamics at the specific time of sacrifi.ce of the present study indeed differed between the two groups. Thus, the results obtained in the present study following afternoon injections of 25 pg mel into female hamsters exposed to short photoperiods are for the most part confirmatory of previous work (22,1,33,36,26,32,34,12). This includes the increase in ovarian weight which is a result of a proliferation of interstitial tissue and is indicative of a regressed ovary (27).…”

Section: Discussionsupporting

confidence: 92%

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THE INFLUENCE OF LARGE DOSES OF MELATONIN ADMINISTERED IN THE AFTERNOON ON THE NEUROENDOCRINEREPRODUCTIVE SYSTEM OF FEMALE SYRIAN HAMSTERS MAINTAINED EITHER IN A LONG OR SHORT PHOTOPERIOD

1982

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Adult female hamsters were maintained on either a long (l4L: 10D; lights on 0600) or short (l0L: 14D; lights on 0600) photoperiod. Within each photoperiodic regimen the animals were injected daily with either vehicle, 25 pg of melatonin (mel) or 2.5 mg of mel at 1600. Short photoperiod resulted in an inhibitory influence on vaginal cyclicity, uterine weight, plasma follicle-stimulating hormone (FSH) and pituitary prolactin (PRL). One hundred percent of both 14:10 and 10:14 LD female hamsters receiving 25 pg mel injections for ll weeks became acyclic along with significant decreases in uterine and anterior pituitary weights. Plasma luteinizing hormone (LH), FSH and PRL titers were significantly depressed in 14 : 10 LD animals injected with 25 pg of mel while no effect on these hormones was observed in 10: 14 LD animals. Pituitary concentrations of LH and FSH were increased in both short day and long day exposed hamsters injected with 25 pg mel; pituitary PRL was depressed in both groups. Hypothalamic luteinizing hormone releasing hormone (LH-RH) was increased in the 10: 14 LD animals receiving 25 pg of mel. Injections of 2.5 mg of mel failed to alter any of the parameters measured in 14 : 10 LD animals with the exception of plasma FSH which was depressed. However, in 10 : 14 LD hamsters the 2.5 mg injections appeared to prevent most of the antigonadotrophic effects of short photoperiod. These results demonstrated that a large bolus of mel given in the afternoon when smaller doses of the indole are known to have inhibitory actions on reproduction, either failed to have any effect or counteracted the antigonadotrophic influence of a short photoperiod.When Syrian hamsters are exposed to short photoperiodic conditions (<12.5h light/day), collapse of the reproductive system ensues (23, 11). Surgical extirpation of the pineal gland prevents the inhibitory effects of reduced photoperiod on the reproductive capacity of these animals (21). The pineal methoxyindole, melatonin (mel), is known to mimic the antigonadotrophic effects of short photoperiod in hamsters when 'low' doses (25 pg or less) are injected daily. However, mel administration must be carried out late in the light phase to inhibit reproduction (36, 37). In light of the suppressive actions of mel, it seems inconsistent that the same indole can also thwart the antigonadal influence of a short photoperiod (14, 30) and even more interestingly, its own antigonadotrophic effects (29, 37) when administered as a subcutaneous implant. Recently, Chen er a1., (7) and Richardson er al. (31) have demon-

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Section: Discussionsupporting

confidence: 92%

“…The antigonadotrophic effects of exogenously administered mel in Syrian hamsters are well documented (36,26,32,34) and are similar to the inhibitory effects of short photoperiod alone (22,1,33,12). This was also the case in the present study with the ex- ception of pituitary LH and FSH.…”

Section: Discussionmentioning

confidence: 95%

THE INFLUENCE OF LARGE DOSES OF MELATONIN ADMINISTERED IN THE AFTERNOON ON THE NEUROENDOCRINEREPRODUCTIVE SYSTEM OF FEMALE SYRIAN HAMSTERS MAINTAINED EITHER IN A LONG OR SHORT PHOTOPERIOD

1982

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“…In the male Syrian hamster, a photoperiod of <12 h light results in a decrease in plasma levels of FSH, LH, testosterone, and prolactin (Berndtson & Desjardins, 1974;Kelly et al, 1994), as well as a decrease in testicular weight and volume associated with both testicular germ cell loss and atrophy of the seminiferous epithelium . For this reason, the Syrian hamster is a good model for studying the control of reproduction through changes in photoperiod (Reiter, 1980;P evet, 1988).…”

Section: Introductionmentioning

confidence: 99%

Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod

et al. 2015

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SUMMARYDuring the non-breeding season some animals exhibit testicular atrophy, decreased testicular weight and reduced seminiferous tubule diameter accompanied by depletion of the seminiferous epithelium. Some cellular factors involved in this depletion are changes in germ cell proliferation and apoptosis. In the Syrian hamster this depletion has been studied histologically and in terms of the involvement of proliferation and apoptosis in the seminiferous epithelium of fully regressed testes. The objectives of this study included the histomorphometrical characterization of the testis and the determination of the proliferative and apoptotic activity of germ cells in the seminiferous epithelium during testicular regression owing to short photoperiod. The study was performed using conventional light microscopy (hematoxylin and eosin), proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP in situ nick end labelling staining, image analysis software, and transmission electron microscopy in three established regression groups: mild regression (MR), strong regression (SR), and total regression (TR). Morphometrically a gradual decrease in total tubular area and in the testicular, tubular, and epithelial volumes was observed during testicular regression. Interstitial and luminal volumes decreased from the MR group onwards. The tubular length decreased from MR to SR. As regards spermatogonial proliferation, only an initial decrease in proliferative activity was observed, whereas apoptotic germ cell activity increased throughout regression. The number of germ cells studied decreased throughout the process of testicular regression. In conclusion, testicular regression in Syrian hamster comprises two histomorphometrical phases, the first involving a decrease in seminiferous tubular diameter and volume and the second involving shortening of the seminiferous tubule and a decrease in interstitial volume. At the cellular level, there is an initial decrease in proliferation and increase in apoptosis involving all germ cells. At the end of regression, the proliferative and apoptotic activities of the spermatogonia recover the values observed prior to regression in preparation for recrudescence.

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“…Intra-assay variation was 5% (LH) and 7-6% (FSH). These assays have been previously validated for use in the hamster (Berndtson & Desjardins, 1974) and mouse (Beamer, Murr & Geschwind, 1972). Statistical analysis was by Student's t test.…”

Section: Introductionmentioning

confidence: 99%

Abnormal gonadotrophin release from pituitaries of muscular dystrophic mice and hamsters

Wilkinson¹

1984

Reproduction

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Circulating LH and FSH Levels and Testicular Function in Hamsters During Light Deprivation and Subsequent Photoperiodic Stimulation¹

Cited by 245 publications

References 2 publications

<b>THE INFLUENCE OF LARGE DOSES OF MELATONIN ADMINISTERED IN THE AFTERNOON ON THE NEUROENDOCRINEREPRODUCTIVE SYSTEM OF FEMALE SYRIAN HAMSTERS MAINTAINED EITHER IN A LONG OR SHORT </b><b>PHOTOPERIOD </b>

<b>THE INFLUENCE OF LARGE DOSES OF MELATONIN ADMINISTERED IN THE AFTERNOON ON THE NEUROENDOCRINEREPRODUCTIVE SYSTEM OF FEMALE SYRIAN HAMSTERS MAINTAINED EITHER IN A LONG OR SHORT </b><b>PHOTOPERIOD </b>

Testicular histomorphometry and the proliferative and apoptotic activities of the seminiferous epithelium in Syrian hamster (Mesocricetus auratus) during regression owing to short photoperiod

Abnormal gonadotrophin release from pituitaries of muscular dystrophic mice and hamsters

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