Effects of testosterone either alone or with IGF-I on growth of cells derived from the proliferation zone of regenerating antlers in vitro

Sadighi, M; Li, C.; Littlejohn, R. P.; Suttie, J. M.

doi:10.1054/ghir.2001.0232

Cited by 30 publications

(32 citation statements)

References 14 publications

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“…This is confirmed by in vitro studies that have been unable to demonstrate a direct effect of testosterone on the proliferation of mesenchymal or cartilage cells, despite the presence of tesosterone binding sites. The same group found that testosterone did not sensitize antler cells to the effects of IGF-I (Li et al 1999;Sadighi et al 2001), which has been proposed to be the elusive AGS (Suttie et al 1985). AGS is the non-gonadal trophic factor whose existence was first suggested 60 years ago (Wislocki 1943).…”

Section: The Control Of Antler Developmentmentioning

confidence: 99%

Exploring the mechanisms regulating regeneration of deer antlers

Price

Allen

2004

Phil. Trans. R. Soc. Lond. B

110

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Deer antlers are the only mammalian appendages capable of repeated rounds of regeneration; every year they are shed and regrow from a blastema into large branched structures of cartilage and bone that are used for fighting and display. Longitudinal growth is by a process of modified endochondral ossification and in some species this can exceed 2 cm per day, representing the fastest rate of organ growth in the animal kingdom. However, despite their value as a unique model of mammalian regeneration the underlying mechanisms remain poorly understood. We review what is currently known about the local and systemic regulation of antler regeneration and some of the many unsolved questions of antler physiology are discussed. Molecules that we have identified as having potentially important local roles in antlers include parathyroid hormone-related peptide and retinoic acid (RA). Both are present in the blastema and in the rapidly growing antler where they regulate the differentiation of chondrocytes, osteoblasts and osteoclasts in vitro. Recent studies have shown that blockade of RA signalling can alter cellular differentiation in the blastema in vivo. The trigger that regulates the expression of these local signals is likely to be changing levels of sex steroids because the process of antler regeneration is linked to the reproductive cycle. The natural assumption has been that the most important hormone is testosterone, however, at a cellular level oestrogen may be a more significant regulator. Our data suggest that exogenous oestrogen acts as a 'brake', inhibiting the proliferation of progenitor cells in the antler tip while stimulating their differentiation, thus inhibiting continued growth. Deciphering the mechanism(s) by which sex steroids regulate cell-cycle progression and cellular differentiation in antlers may help to address why regeneration is limited in other mammalian tissues.

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Section: The Control Of Antler Developmentmentioning

confidence: 99%

Exploring the mechanisms regulating regeneration of deer antlers

Price

Allen

2004

Phil. Trans. R. Soc. Lond. B

110

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“…testosterone and its derivatives) underlies the development of exaggerated male traits in many vertebrate lineages, including the lion's mane [16], swordtail swords [17], and dimorphism in body size and secondary sexual traits in lizards [11,15]. Alternatively, the insulin-like growth factor (IGF) pathway is thought to produce an honest signal of male condition owing to its sensitivity to nutritional condition, such as in the development of exaggerated rhinoceros beetle horns [18], deer antlers [19] and avian size dimorphism [20].…”

Section: Introductionmentioning

confidence: 99%

The oestrogen pathway underlies the evolution of exaggerated male cranial shapes in Anolis lizards

et al. 2014

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Sexual dimorphisms vary widely among species. This variation must arise through sex-specific evolutionary modifications to developmental processes. Anolis lizards vary extensively in their expression of cranial dimorphism. Compared with other Anolis species, members of the carolinensis clade have evolved relatively high levels of cranial dimorphism; males of this clade have exceptionally long faces relative to conspecific females. Developmentally, this facial length dimorphism arises through an evolutionarily novel, clade-specific strategy. Our analyses herein reveal that sex-specific regulation of the oestrogen pathway underlies evolution of this exaggerated male phenotype, rather than the androgen or insulin growth factor pathways that have long been considered the primary regulators of male-biased dimorphism among vertebrates. Our results suggest greater intricacy in the genetic mechanisms that underlie sexual dimorphisms than previously appreciated.

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“…When male deer carrying velvet antlers are castrated (Blauel, 1935;Wislocki et al, 1947;Goss, 1968) or treated with the antiandrogen cyproterone acetate (Bubenik GA et al, 1975;Kolle et al, 1993), the velvet is not shed. So far, it is a matter of debate whether or not antler growth itself requires (direct or indirect) stimulation by low levels of androgens (Bubenik GA, 1983Schams et al, 1992;Kolle et al, 1993;Suttie et al, 1995;Bartoš et al, 2000;Sadighi et al, 2001).…”

mentioning

confidence: 99%

Histological structure of antlers in castrated male fallow deer (Dama dama)

Kierdorf

Schultz

et al. 2004

Anat. Rec.

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Antlers are periodically replaced cranial appendages that, except for the reindeer, are grown only by male deer. The annual antler cycle is controlled by seasonal fluctuations of sex steroid concentrations in the blood, and accordingly castration of male deer causes deviations from normal antler growth. The present study investigated antler histology of castrated fallow bucks (Dama dama). Castration in early spring was followed by casting of the hard antlers carried by the bucks and the growth of a new set of antlers, which remained in velvet permanently. In the following year, numerous bony protuberances developed from the original antler surface. Further growth of these protuberances, which were formed by subperiosteal intramembranous ossification, led to a marked increase in antler diameter in the affected areas. Compared to antlers of intact bucks, the antlers of the castrates showed histological signs of immaturity, suggestive of a reduced bone remodeling and an impairment of the mineralization process. These changes point to the dependence of the above processes on a stimulation by higher levels of sex steroids. Two years after castration, the antlers also developed integumental thickening and showed an initial formation of skin outgrowths. Cystic structures were present in the skin, which were often filled with a presumably sebaceous and/or keratinous material. Formation of intradermal bone or cartilage was not observed in the antlers of the castrated fallow bucks. The histological structure of the skin outgrowths suggested that they were caused by a hypertrophy of the dermal component of the velvet. Due to the localized bone overgrowth, resulting from the periosteal bone apposition onto the original antler surface, skin-lined infoldings originated, which reached deep into the newly formed bone. Our study revealed no indication of invasive/destructive bone growth in the antlers, i.e., of a penetration of the newly formed bone tissue into the pre-existing bone. The hypertrophic bone growth in the antlers of the castrates is compared with other forms of periosteally derived hypertrophic bone formation, including osteomas, in the mammalian skeleton. It is discussed whether the skin and bone outgrowths of the antlers of castrated fallow bucks may be classified as benign tumors. Key words: antler; fallow deer (Dama dama); castration; bone; skin; histology Antlers are periodically cast and regenerated cranial appendages that develop on top of permanent processes (pedicles) of the frontal bones of deer. Except for the reindeer (Rangifer tarandus), in which both sexes carry antlers, these are normally grown only by male deer (Goss, 1983;Lincoln, 1992). Since the antler physiology of reindeer differs markedly from that in other deer species, this special case is not considered further and only the typical situation in male deer will be presented.The annual antler cycle is controlled by seasonal fluctuations in the blood levels of sex steroids

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Effects of testosterone either alone or with IGF-I on growth of cells derived from the proliferation zone of regenerating antlers in vitro

Cited by 30 publications

References 14 publications

Exploring the mechanisms regulating regeneration of deer antlers

Exploring the mechanisms regulating regeneration of deer antlers

The oestrogen pathway underlies the evolution of exaggerated male cranial shapes in Anolis lizards

Histological structure of antlers in castrated male fallow deer (Dama dama)

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