Alterations in Hypothalamic Content of Luteinizing Hormone-Releasing Hormone Associated with Pineal-Mediated Testicular Regression in the Golden Hamster
1

Jackson, Fred L.; Heindel, Jerrold J.; Preslock, James P.; Berkowitz, Albert S.

doi:10.1095/biolreprod31.3.436

Cited by 40 publications

(22 citation statements)

References 27 publications

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“…The reduced release of this peptide could in turn be responsible for the decrease in circulating gonadotropin levels and testicular function, as reported previously [2, 3, 5, 24, 27, 28]. Although the period of SD exposure was far shorter in the present study than in earlier reports, the results were consistent with previous findings, as shown in table 1.…”

Section: Discussionsupporting

confidence: 93%

“…In seasonal breeding mammals, secretion of GnRH by the hypothalamus depends upon the photoperiod [1, 2, 3, 4, 5]. In long-day breeding rodents, exposure to short-day (SD) photoperiods suppresses gonadal function and increases the number and the staining intention of GnRH-immunoreactive (ir) neurons, and hypothalamic GnRH content [2, 3, 4, 5, 6, 7, 8, 9, 10].…”

Section: Introductionmentioning

confidence: 99%

“…In long-day breeding rodents, exposure to short-day (SD) photoperiods suppresses gonadal function and increases the number and the staining intention of GnRH-immunoreactive (ir) neurons, and hypothalamic GnRH content [2, 3, 4, 5, 6, 7, 8, 9, 10]. However, studies in hamsters, typical long-day breeding rodents, have been restricted to just two species, Syrian (Mesocricetus auratus) and Siberian (Phodopus sungorus) hamsters [2, 3, 4, 5, 6, 10], and in other rodents to relatively few species, such as white-footed mice (Peromyscus leucopus) , deer mice (Peromyscus maniculatus) and prairie voles (Microtus ochrogaster) [7, 8, 9]. In the present work, we investigated the effects of several environmental factors on the GnRH neuronal system in the gray hamster, Tscherskia triton.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Photoperiod and Ambient Temperature on the Gonadotropin-Releasing Hormone Neuronal System in the Gray Hamster, <i>Tscherskia triton</i>

et al. 2000

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In seasonal breeders like the hamster, gonadal function depends on the photoperiod. The present study examined the effects of different photoperiods and ambient temperatures on the gonadotropin-releasing hormone (GnRH) neuronal system in male gray hamsters, Tscherskia triton. Hamsters were kept from birth under a long-day (LD: 16 h light and 8 h dark) photoperiod and at 23°C until the experiment began. The animals were then kept for 30 days under different photoperiods and ambient temperatures. After autopsy, immunocytochemical and semiquantitative reverse transcription-polymerase chain reaction analyses were performed on the hamster forebrain. Exposure to a short-day (SD: 8 h light and 16 h dark) photoperiod at 23°C induced a functional decline in the GnRH neuronal system (increased neuron number and immunoreactivity, and reduced cell size). LD with low ambient temperature (7°C) did not influence the GnRH neuronal system. In contrast, SD with low ambient temperature enhanced the SD-induced functional decline in GnRH neurons. Changes in immunoreactivity of GnRH fibers in the median eminence, their release site, were also similar to those in neuronal perikarya. Significant differences in GnRH gene expression were detected in the SD only group and the SD with low ambient temperature group. However, no differences were detected between the two groups. These findings suggest that low ambient temperature enhanced the SD-induced decline in GnRH release from nerve terminals, but was not a crucial factor in the synthesis of this decapeptide.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Photoperiod and Ambient Temperature on the Gonadotropin-Releasing Hormone Neuronal System in the Gray Hamster, <i>Tscherskia triton</i>

et al. 2000

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“…For example, in P. leuco pus exposure to short photoperiod [10], blinding or treat ment with a subcutaneous melatonin implant [23] increases the intensity of immunocytochemical staining for GnRH in the median eminence (ME). In the Syrian hamster, expo sure to short photoperiod increases hypothalamic contents of radioimmunoassayable GnRH [16,24,28]. On the basis of these observations, it is possible that melatonin may sup press the rate of release of GnRH from the ME to a level that is not sufficient to maintain the reproductively active state.…”

mentioning

confidence: 99%

A Brain Site for the Antigonadal Action of Melatonin in the White-Footed Mouse (Peromyscus (leucopus): Involvement of the Immunoreactive GnRH Neuronal System

Glass¹,

Knotts²

1987

Neuroendocrinology

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Quantitative assessment of immunocytochemical staining for gonadotropin-releasing hormone (GnRH) was undertaken to determine the effects of an intracranial implant of melatonin on the GnRH neuronal system in the male white-footed mouse (Peromyscus leucopus). Melatonin-containing pellets stereotaxically placed in the anterior hypothalamic area (AH) caused a 60% reduction in testes weight relative to control mice with melatonin-free pellets in the AH (p< 0.01). Subcutaneous melatonin-containing implants had little effect on reproductive state (p < 0.8). Melatonin pellets in the AH increased significantly both the optical density (OD) for immunostaining of cell bodies in the medial preoptic area and AH (p < 0.04), and the percentage of area covered by GnRH fibers and beads in the median eminence (p < 0.01). The melatonin-induced increase in OD of the GnRH cell bodies was independent of the distance of the cells from the melatonin implant, and there was little apparent effect of melatonin on the size and morphology of the GnRH cell bodies, or the trajectories of their fiber pathways. These results support the hypothesis that the antigonadal action of melatonin in the brain involves suppression of the release, rather than the synthesis of GnRH. Also, this effect may not be mediated via a direct action of melatonin on GnRH neurons. The finding that the brain site and time course for melatonin’s antigonadal action in male. P. leucopus is similar to that found previously in the female is evidence that melatonin may induce gonadal regression, in part, by helping to suppress the tonic secretion of gonadotropins.

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“…The level of inbreeding did not affect true V E and OI (Bongers et al 1997b). Outbred (1) Outbred ( Jackson et al 1984; (e) Bongers et al (1988, in press); (f) Komen et al 1993; (g) Bongers et al 1997c iation than (partly) outbred stocks. However, in most cases the [partly) outbred stocks in this table can be considered more as inbred strains than outbred stocks.…”

Section: Residual Variation Within Inbred Strainsmentioning

confidence: 90%

Development and use of genetically uniform strains of common carp in experimental animal research

Bongers¹,

Sukkel²,

Gort

et al. 1998

Lab Anim

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SummaryFish are widely used in numerous fields of basic and applied research. Currently, they are the third laboratory animal group in numbers, and will become increasingly important. Common carp is a major species in both aquaculture and research. Inbred strains of carp by gynogenetic (only female inheritance) and androgenetic (only male inheritancel reproduction techniques were developed at our university. With these methods, homozygous animals are produced in one generation and we present the production of homozygous inbred and FI hybrid strains of common carp.As in mammalian research, using genetically well defined fish is a methodological necessity since in outbred stocks: (1) repeatability between experiments is low, (2) high levels of inbreeding may have accumulated and (3) high intrastrain variability might obscure treatment effects. Within inbred strains, the variation is reduced and as a result, less animals (compared to outbreds) are necessary to obtain statistically significant results. We illustrate this with experimental data from an FI hybrid and partly outbred strain of common carp, both subjected to an antibiotic treatment resulting in reduced gonadal growth.Results obtained from a single inbred strain should be generalized with the use of a panel of inbred strains. We show that optimal allocation of animals between and within inbred strains depends on the ratio (variation between strainsl : (variation within strains). When selecting a panel of inbred strains, attention has to be paid to genetic relations between strains to avoid testing within a limited genetic range. It should be considered that in inbred strains, (genic) dominance and interaction effects are absent, due to the absence of heterozygous genotypes.In general, variation within inbred strains will be reduced for traits with a high degree of genetic determination. However, in inbred strains of carp produced by gynogenesis or androgenesis, the chromosome manipulation treatment induces considerable (environmental) variation. By using FI hybrids of carp, derived from crossing homozygous clonal siblings this source of variation can be avoided. Still, variation in FI hybrids of carp is relatively large and varies greatly between strains when compared to inbred strains of laboratory rodents. It is assumed that their poikilothermic nature makes them more susceptible to environmental variation. Using inbred fish lines will increase experimental quality and leads to a more efficient use of experimental animals. KeywordsCyprinus carpio; common carp; gynogenesis; androgenesis; inbred strain; toxicology; fish Fish are widely used in the field of neurobiology, endocrinology, immunology, developmental biology, aquatic toxicology and cancer research, The advantages of fish as

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Alterations in Hypothalamic Content of Luteinizing Hormone-Releasing Hormone Associated with Pineal-Mediated Testicular Regression in the Golden Hamster 1

Cited by 40 publications

References 27 publications

Effects of Photoperiod and Ambient Temperature on the Gonadotropin-Releasing Hormone Neuronal System in the Gray Hamster, <i>Tscherskia triton</i>

Effects of Photoperiod and Ambient Temperature on the Gonadotropin-Releasing Hormone Neuronal System in the Gray Hamster, <i>Tscherskia triton</i>

A Brain Site for the Antigonadal Action of Melatonin in the White-Footed Mouse (Peromyscus (leucopus): Involvement of the Immunoreactive GnRH Neuronal System

Development and use of genetically uniform strains of common carp in experimental animal research

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