Seasonal changes in plasma concentrations of gonadotropins and in the responsiveness of the pituitary and testis to GnRH in a desert rodent, the sand rat (Psammomys obesus)

Khammar, Farida; Brudieux, R

doi:10.1051/rnd:19910607

Cited by 6 publications

(3 citation statements)

References 14 publications

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“…In the sand rat (Psammomys obesus), a short day breeder, plasma LH concentration increases in early summer and that intravenous administration of GnRH (200 ng/100 g of body weight) fails to elicit significant season-dependent changes in LH release, whereas the increase in plasma testosterone was maximum in June-July and low between November and March-April. The summer seasonal onset of the testicular endocrine activity of the sand rat is due to increases in both in LH release and testes sensitivity to gonadotropin [34]. Other studies showed that GnRH is involved in the regulation of pituitary gonadotropin secretion by a system that depends on frequency pulsations.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season

Boufermes

Belhocine

Amirat

et al. 2021

Animals

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The Libyan jird (Meriones libycus, 1823) is a wild desert rodent that is a seasonal breeder species adapted to breed when the environmental conditions can satisfy the energy and hydrous requirements of pregnant and nursing females to ensure that births occur at the most favorable time of the year. We assessed gene expression of testicular luteinizing hormone receptor (Lhcgr) correlated to testis activity. The expression of Lhcgr was evaluated using quantitative Real Time-Polymerase Chain Reaction (qRT-PCR and the testis activity by a histological method in adult male Libyan jirds during the nonbreeding and breeding seasons. Our results showed that Lhcgr mRNA expression increased in autumn during the nonbreeding season and decreased in spring during the breeding season. This expression varied in contrast to testicular structure or function and plasma testosterone levels. These results help to elucidate this desert rodent’s seasonal sexual activity, which is correlated with central regulation.

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Section: Discussionmentioning

confidence: 99%

Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season

Boufermes

Belhocine

Amirat

et al. 2021

Animals

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“…However, in the jerboa, striking seasonal changes in GnRH expression in the POA appear to be independent of photoperiod, and also independent of both seasonal variations in food availability and environmental temperature. As concerns the sex steroids–GnRH interaction, a functional relation has been well established in mammals (29–33). Recently, evidence has been provided that the GnRH receptor mRNA is positively regulated during the morning of proestrus, probably following an increase in the level of oestradiol, in preparation for the preovulatory GnRH‐LH surge (30).…”

Section: Discussionmentioning

confidence: 99%

The Gonadotropin‐Releasing Hormone Neurosecretory System of the Jerboa (Jaculus orientalis) and its Seasonal Variations

Ouezzani

Tramu²,

Magoul

2000

J Neuroendocrinology

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The distribution of cells expressing gonadotropin-releasing hormone (GnRH) immunoreactivity was examined in the brain of adult jerboa during two distinct periods of the reproductive cycle. During spring-summer, when the jerboa is sexually active, a high density of cell bodies and fibres immunoreactive (IR) for GnRH was observed at the level of separation of the frontal lobes, in the medial septal nucleus (MS) and in the diagonal band of Broca (DBB), in the preoptic area (POA), in the organum vasculosum laminae terminalis (OVLT), in the retrochiasmatic area and hypothalamus. In autumn, when the jerboa is sexually inactive, GnRH-immunoreactivity was less intense than during spring-summer. In the POA, we noted a 55% decrease in the number of GnRH containing cells with no change in cell numbers in the MS-DBB. Furthermore, a lower density of GnRH immunopositive axon fibres is observed in all the previously mentioned structures and the immunoreaction intensity was very weak particularly within the median eminence and OVLT. Independently of the season, the GnRH immunoreactivity within neurones and fibres was similar in jerboas living in captivity and in jerboas living in their natural biotope. The effects of photoperiod on the density of POA-GnRH and arcuate nucleus beta-endorphin-containing cells were studied in jerboas maintained in long day [(LD) 16-h light, 8-h dark] and short day [(SD) 8-h light, 16-h dark] for 8 weeks. In the POA, the GnRH-IR cell number was not significantly altered by the photoperiod. Similarly, in the mediobasal hypothalamus, the number of beta-endorphin-IR neurones was not affected by such a parameter. Consequently, the GnRH seasonal variations cannot be correlated to changes in the photoperiod alone.

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“…Indeed, this species constituted a model for studying several metabolic disorders when confined to standard laboratory diet, Psammomys develops diabetes [22,23] and other pathology [24,25]. In the male, different studies were already published [26][27][28]. In the female, the estrous cycle was characterized [29], in the gonad the histological aspect was published [30], the histological and cytological seasonal variations of the reproductive tract were studied [31].…”

Section: Introductionmentioning

confidence: 99%

Morphometry and immunohistochemistry of follicles growth and steroidogenesis in saharian wild sand rat, Psammomys obesus, ovary.

Boubekri

Gernigon-Spychalowicz²,

Khammar³

et al. 2010

Folia Histochem Cytobiol.

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Abstract:The sand rat (Psammomys obesus) constitutes a model to study seasonal changes and several metabolic disorders. In order to perform breeding laboratory conditions, the reproductive function of this species living in North Occidental Algerian Sahara was studied. The aim of this work was to investigate the follicular growth changes and the steroidogenic associated aspects. The study was performed using morphometrical and immunohistochemical methods. From primordial to preantral states, the follicle diameter increased progressively from 17-20 μm to 192-225 μm. The preovulatory follicles reached about 500 μm in diameter. Immunoreactivity to progesterone, androstenediol and estradiol, varied in the different parts of the ovary and follicular cells. The progesterone antibody appeared clearly labelled in the theca interna of the growing follicle and increased in the granulosa; the androgen antibody was continuously weak and diffuses in all follicles; the estradiol labelling appeared weak and diffuse in preantral follicles then increased in antral follicles in both theca and granulosa or only in granulosa. In antral follicles, estradiol label was clearly localized in granulosa cells and totally devoid in theca cells. In Psammomys ovary, labels of hormone were diffuse or localized, weak or intense in the theca and or in the granulosa according to the follicle size.

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Seasonal changes in plasma concentrations of gonadotropins and in the responsiveness of the pituitary and testis to GnRH in a desert rodent, the sand rat (Psammomys obesus)

Cited by 6 publications

References 14 publications

Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season

Assessment of Testicular Lhcgr mRNA Expression Correlated with Testis and Seminal Vesicle Activities in the Libyan jird (Meriones libycus, Rodentia: Muridae) during Breeding Season Compared with Nonbreeding Season

The Gonadotropin‐Releasing Hormone Neurosecretory System of the Jerboa (Jaculus orientalis) and its Seasonal Variations

Morphometry and immunohistochemistry of follicles growth and steroidogenesis in saharian wild sand rat, Psammomys obesus, ovary.

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