Social Status and Sex Effects on Neural Morphology in Damaraland Mole-Rats, &lt;i&gt;Fukomys damarensis&lt;/i&gt;

Anyan, Jeff J.; Seney, Marianne L.; Holley, Amanda; Bengston, Lynn; Goldman, Bruce D.; Forger, Nancy G.; Holmes, Melissa M.

doi:10.1159/000328640

Cited by 16 publications

(10 citation statements)

References 47 publications

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“…Instead, the heterogeneity of the expression indicates the existence of distinct neuron-subpopulations in this region that differ in their steroid hormone sensitivity. Previous studies using Nissl-stained sections of both naked mole-rats and Damaraland mole-rats also failed to identify such a distinct cell group within the medial preoptic area [ 7 , 10 , 38 ]. With ARO as a marker, we found in all three groups of females a cluster of expression in the MPOA, which caudally of the anterior commissure merges with the BST to form a V-shaped structure (Figures 2 and 4 ).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, breeding naked mole-rats, regardless of sex, were found to have significantly less androgen receptor-immunoreactive cells in those areas than non-breeders [8,9]. A recent study in Damaraland mole-rats ( Fukomys damarensis ) reports similar results concerning social status-related differences in gross morphology for the BSTp and PVN but not for the MeA [10]. …”

Section: Introductionmentioning

confidence: 96%

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Breeding status and social environment differentially affect the expression of sex steroid receptor and aromatase mRNA in the brain of female Damaraland mole-rats

et al. 2014

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IntroductionThe Damaraland mole-rat (Fukomys damarensis) is a eusocial, subterranean mammal, which exhibits an extreme reproductive skew with a single female (queen) monopolizing reproduction in each colony. Non-reproductive females in the presence of the queen are physiologically suppressed to the extent that they are anovulatory. This blockade is thought to be caused by a disruption in the normal gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. In order to understand the underlying physiological mechanisms of reproductive suppression in subordinate females we studied the expression of steroid hormone receptors and the androgen-converting enzyme aromatase in forebrain regions involved in the control of reproductive behaviour in female breeders and non-breeders from intact colonies. Additionally, we included in our analysis females that experienced the release from social suppression by being removed from the presence of the queen.ResultsWe found expression of androgen receptor, estrogen receptor α and aromatase in several forebrain regions of female Damaraland mole-rats. Their distribution matches previous findings in other mammals. Quantification of the hybridisation signal revealed that queens had increased expression of androgen receptors compared to non-breeders and removed non-breeders in most brain regions examined, which include the medial preoptic area (MPOA), the principal nucleus of the bed nucleus of the stria terminalis (BSTp), the ventromedial nucleus of the hypothalamus (VMH), the arcuate nucleus (ARC) and the medial amygdala (MeA). Furthermore, breeders had increased estrogen receptor α expression in the anteroventral periventricular nucleus (AVPV) and in the MeA, while aromatase expression in the AVPV was significantly reduced compared to non-breeders. Absence of social suppression was associated with increased androgen receptor expression in the ARC, increased estrogen receptor α expression in the MeA and BSTp and reduced aromatase expression in the AVPV.ConclusionThis study shows that social suppression and breeding differentially affect the neuroendocrine phenotype of female Damaraland mole-rats. The differential expression pattern of estrogen receptor α and aromatase in the AVPV between breeders and non-breeders supports the view that this region plays an important role in mediating the physiological suppression in subordinate females.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Breeding status and social environment differentially affect the expression of sex steroid receptor and aromatase mRNA in the brain of female Damaraland mole-rats

et al. 2014

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“…Our recent findings in female Damaraland mole‐rats (Voigt et al ., ), led us to investigate to what extent the difference in reproductive behaviour affects the neuroendocrine phenotype of males in this species. Previous work identified social status‐related gross‐morphological differences concerning two brain areas involved in reproductive behaviour, the principal nucleus of the bed nucleus of the stria terminalis (BSTp) and the paraventricular nucleus (PVN) being larger in reproductive males than in non‐reproductive males (Anyan et al ., ). However, the properties of steroid‐hormone‐sensitive neuron populations in hypothalamic and limbic regions of males are unknown.…”

Section: Introductionmentioning

confidence: 97%

Breeding status affects the expression of androgen and progesterone receptor mRNA in the brain of male Damaraland mole‐rats

2015

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The eusocial Damaraland mole-rat (Fukomys damarensis) represents an extreme example of reproductive skew, in that reproduction is completely blocked in female subordinate group members. Similarly, male subordinates within the colony show no sexual behaviour. In contrast to females, however, non-reproductive males have functional gonads and do not differ in circulating levels of pituitary hormones and testosterone from reproductive males. Nevertheless, they have reduced numbers of follicle-stimulating hormone receptors in their testes and they produce fewer spermatozoa with a large proportion of immature spermatozoa and precursors. To understand the mechanism of reproductive suppression operational in subordinate males we studied the expression of androgen and progesterone receptor genes in forebrain regions involved in the control of reproductive behaviour in male breeders and nonbreeders from intact colonies. While it is well documented that testosterone activates maletypical behaviour, the role of progesterone in this process is less clear as previous studies have produced contradictory results. We found expression of androgen receptor (AR) and progesterone receptor (PGR) genes in several forebrain regions of male Damaraland molerats. The distribution of AR in males matches our previous findings in females. This is the first report showing the distribution of PGR in mole-rats. We found PGR in all areas which were also sensitive to androgens and estrogens. Analysis of the optical densities of the AR and PGR hybridisation signal revealed that breeding males had increased expression of AR and PGR compared to non-breeders in most brain regions examined, which include the medial preoptic area, the bed nucleus of the stria terminalis, the ventromedial nucleus of the hypothalamus, the arcuate nucleus and the medial amygdala. These status-related differences were more pronounced for PGR than for AR. This study shows that breeding position affects the neuroendocrine phenotype of male Damaraland mole-rats. Further, it suggests that androgens and progesterone might act synergistically in activating sexual behaviour in males.3

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“…These include an increase in brain volume, pituitary sensitivity, reproductive hormone concentrations, and body length Bennett 1994;Bennett et al 1994;Bennett et al 1996;Young & Bennett 2010;Anyan et al 2011). Although it has yet to be explored, it is possible that some of these adjustments could be correlated with extended longevity.…”

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confidence: 99%

The long-lived queen: reproduction and longevity in female eusocial Damaraland mole-rats (Fukomys damarensis)

2013

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The inverse relationship between reproduction and lifespan is one of the main concepts of life history theory. This association has been observed in most taxa, although exceptions have been found in which a breeding female outlives her non-reproductive cohorts. This relationship is well known in social insects, and it has recently come to light that reproductive females of certain social mole-rat species also exhibit extended lifespans relative to non-breeders. We analysed mark-recapture data over 13 years in 12 colonies of Damaraland mole-rats (Fukomys damarensis) to assess if colony queens lived longer than non-reproductive adult females. Queens were recaptured up to 8.5 years after initial capture (X = 6.2 years); significantly longer than non-reproductive females (X = 1.3 years), suggesting that a colony queen lives longer than her non-reproductive subordinates. This difference may be attributed to both physiological and social factors which may relax reproductive costs in queens.

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Social Status and Sex Effects on Neural Morphology in Damaraland Mole-Rats, <i>Fukomys damarensis</i>

Cited by 16 publications

References 47 publications

Breeding status and social environment differentially affect the expression of sex steroid receptor and aromatase mRNA in the brain of female Damaraland mole-rats

Breeding status and social environment differentially affect the expression of sex steroid receptor and aromatase mRNA in the brain of female Damaraland mole-rats

Breeding status affects the expression of androgen and progesterone receptor mRNA in the brain of male Damaraland mole‐rats

The long-lived queen: reproduction and longevity in female eusocial Damaraland mole-rats (Fukomys damarensis)

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