Secretory activity of gonadotropin and the responsiveness of gonadotrophs to gonadotropin-releasing hormone during the annual reproductive cycle of male bats,Rhinolophus ferrumequinum: Analysis by cell immunoblot assay

Kawamoto, Keiichi; Tanaka, Susumu; Hayashi, Toshiyuki

doi:10.1002/1097-010x(20000801)287:3<213::aid-jez3>3.0.co;2-n

Cited by 12 publications

(5 citation statements)

References 54 publications

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“…The present immunohistochemical study of the LHβ and FSH‚ cells of the pars distalis of Lagostomus maximus maximus during the annual reproductive cycle and after the chronic administration of melatonin demonstrates that: 1) the LHβand FSH‚ cells exhibit seasonal variations in their distribution, size and percentage area occupied during the annual reproductive cycle, 2) the size and percentage area occupied by the LHβ cells reach their maximum values in the reproductive period (summer-early autumn) and they are widely distributed throughout in pars distalis, 3) the administration of melatonin causes a decrease of the cellular size and of the percentage area occupied by the LHβ cells, 4) the size and percentage immunopositive area occupied by the FSHβ cells reach their maximum values in the gonadal recovery period (spring) and they are widely distributed throughout in pars distalis, and 5) the administration of melatonin causes a decrease of the cellular size but not of the percentage immunopositive area occupied by the FSHβ cells. In mice (Kuwahara et al, 2000), bats (Kawamoto et al, 2000) and ruin lizards (Desantis et al, 2000) have observed a decrease in number and size of cells LH in the nonbreeding season suggesting a decrease in the LH hormone synthesis. Variations in the secretion of LH as a function of the gonadal activity were described during the annual reproductive cycle in the mink (Jallageas et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations of gonadotropins in the pars distalis male Viscacha pituitary. Effect of chronic melatonin treatment

Filippa¹,

Penissi²,

Mohamed³

2009

Eur J Histochem

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The gonadotropes, LH and FSH cells, were immunohistochemically identified in the pituitary pars distalis of the adult male viscacha (Lagostomus maximus maximus) using specific antibodies against hLH‚ and hFSH‚ with the streptavidinbiotin- peroxidase complex. The distribution, size and percentage immunopositive area of these cells were analyzed by image analysis in viscachas captured during the annual reproductive cycle and after the chronic administration of melatonin. The LH‚ and FSHb cells showed seasonal changes in the distribution, size and percentage immunopositive area. The LHb cells were found widely distributed throughout the pars distalis during the reproductive period, and they were found in the ventro-medial region in the pars distalis during the gonadal regression and gonadal recovery periods. The LHb cells reached the largest size and immunopositive area during the reproductive period and the smallest size and immunopositive area during the gonadal regression period. The FSHb cells were found in the ventro-medial region during reproductive and gonadal regression periods. The FSHb cells were found widely distributed throughout the pars distalis during the gonadal recovery period when they showed the maximum percentage immunopositive area. A decrease in the size of LH‚ and FSHb cells was observed after the chronic administration of melatonin. Moreover, it produces a decrease in the immunopositive area occupied by the LH‚ cells but not in the immunopositive area occupied by the FSHb cells. Our results show great activity of LHb and FSHb cells in different moments of the annual reproductive cycle demonstrating that these cells are not secrete in parallel. Moreover, melatonin acts differentially on the activity of the gonadotrope cells

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Section: Discussionmentioning

confidence: 99%

Seasonal variations of gonadotropins in the pars distalis male Viscacha pituitary. Effect of chronic melatonin treatment

Filippa¹,

Penissi²,

Mohamed³

2009

Eur J Histochem

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“…Asterisks represent significant differences between males and females, p<0.05. Krishna, 1996a;Kawamoto et al ., 2000a). Our studies of rhinolophid bats of both sexes verified that the immunoreactivity and size of LH β -and FSH β -immunoreactive cells varied significantly throughout the seasons (Fig.…”

Section: (1) Pars Distalismentioning

confidence: 99%

“…5). We found that the seasonal variations in the total amount of gonadotropins secreted from gonadotrophs per unit volume of chamber were considered due to the changes in gonadotropin secretion per cell and in the number of gonadotropinsecreting cells (Kawamoto et al ., 2000a). The total amount of LH secreted from gonadotrophs was marked in spermatogenic and mating periods but extremely small in other phases (post-arousal period, mid-May, and hibernation period, late January).…”

Section: (1) Pars Distalismentioning

confidence: 99%

“…Thus, the responsiveness of gonadotrophs to GnRH also shows seasonal variations, which may be closely associated with the number of GnRH receptors on gonadotrophs and/or with the increased response of gonadotrophs to GnRH caused by the action of gonadal steroids (Conn, 1994;Turzillo et al ., 1998;Kawakami and Winters, 1999). In the hibernation period, the majority of gonadotrophs were composed of non-releasable cells but a slight secretory response of gonadotrophs to GnRH was detected at low incubation temperature (10 ° C, Kawamoto et al ., 2000a). These results suggest that the GnRH receptor and subsequent post-receptor events that regulate the action of GnRH on gonadotropin secretion do not completely disappear under heterothermic conditions during hibernation.…”

Section: (1) Pars Distalismentioning

confidence: 99%

“…2. Reprinted from Kawamoto et al (2000a) with permission from Wiley-Liss, Inc. mitted). In addition, by employing using RT-PCR assay and in situ hybridization we found that exposure to a short-day photoperiod increased the incidence of gonadotropin β mRNA-expressing cells and the level of gonadotropin β mRNA in the hamster pars tuberalis, whereas these were decreased in the pars distalis.…”

Section: ) Pars Tuberalismentioning

confidence: 99%

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Endocrine Control of the Reproductive Activity in Hibernating Bats

Kawamoto

2003

Zoological Science

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Bats, Chiroptera, constitute the second largest order of the class Mammalia and vary greatly in habitats, available foods and mating systems. The timing, duration and patterns of reproduction in bats vary considerably among species and different localities. Though much is known about the reproductive phenomena and associated endocrine characteristics of various species, the central mechanism regulating the peculiar delay and asynchrony in reproductive activity remains to be elucidated. The current understanding on the endocrine characteristics and possible mechanism of regulation of the hypothalamo-adenohypophysial-gonadal axis of bats will be reviewed, based mainly on our own studies in hibernating rhinolophid bats.

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Basic properties and annual changes of follicle‐stimulating hormone receptors in the testis of horseshoe bats, Rhinolophus ferrumequinum

2002

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The unique reproductive patterns, delayed fertilization in females, and asynchrony between spermatogenesis and mating behavior in males are well documented in bats living in temperate latitudes. The present study was undertaken to examine follicle-stimulating hormone (FSH) receptors in the testis of bats, Rhinolophus ferrumequinum, during the annual reproductive cycle. Male bats were captured at natural roosting sites and testicular preparations were subjected to a radioligand binding assay for FSH receptors. The weight of paired testes increased considerably in the spermatogenic period and decreased from the mating to hibernation periods. Meiotic division in the testis was observed in the spermatogenic period but not the mating period. Serum testosterone concentrations increased in the spermatogenic period and rapidly decreased in the mating period. The binding of FSH was specific for mammalian FSHs and detected primarily in the testis. Scatchard plot analyses of the binding of FSH to bat testicular preparations showed straight lines, suggesting the presence of a single class of binding sites. The affinities (equilibrium association constant) of FSH receptors were consistent throughout the annual reproductive cycle. The specific binding per unit weight of testis and total binding in the paired testes were highest in the mating period and in the spermatogenic period, respectively, among reproductive periods. The accumulation of cyclic adenosine 3', 5'-monophosphate to FSH stimulation was higher in the spermatogenic period than in the hibernation period. These findings suggest that testicular function of bats is associated with seasonal changes in the number of binding sites, while the number per target cell and the activation of adenylate cyclase led by FSH-receptor complex considerably decreases in the hibernation period.

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Secretory activity of gonadotropin and the responsiveness of gonadotrophs to gonadotropin-releasing hormone during the annual reproductive cycle of male bats,Rhinolophus ferrumequinum: Analysis by cell immunoblot assay

Cited by 12 publications

References 54 publications

Seasonal variations of gonadotropins in the pars distalis male Viscacha pituitary. Effect of chronic melatonin treatment

Seasonal variations of gonadotropins in the pars distalis male Viscacha pituitary. Effect of chronic melatonin treatment

Endocrine Control of the Reproductive Activity in Hibernating Bats

Basic properties and annual changes of follicle‐stimulating hormone receptors in the testis of horseshoe bats, Rhinolophus ferrumequinum

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