Effects of testosterone on the development of a sexually dimorphic neuromuscular system in ciliary neurotrophic factor receptor knockout mice

Park, Joong Jean; Howell, Michelle; Winseck, Adam; Forger, Nancy G.

doi:10.1002/(sici)1097-4695(19991115)41:3<317::aid-neu1>3.0.co;2-x

Cited by 16 publications

(7 citation statements)

References 49 publications

(78 reference statements)

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“…The LA muscle persisted from birth through at least PND10 in female gerbils. The ontogeny of the perineal muscles in female gerbils is consistent with previous research in adult female rats and mice describing the initial presence and subsequent involution of the BC muscle, and often the LA muscle as well (C ihá k et al, 1970;Breedlove and Arnold, 1983b;Tobin and Joubert, 1988;Forger et al, 1992;Park et al, 1999). TP-treated females that were collected on PND10.…”

Section: Normal Ontogeny Of Bc and La Musclessupporting

confidence: 86%

“…The presence of both the BC and LA muscles in male gerbils at birth is consistent with findings in newborn rats and mice (C ihá k et al, 1970;Breedlove and Arnold, 1983b;Forger et al, 1992;Park et al, 1999). Compared with the LA muscles of male rats, the BC muscles of male gerbils grew more slowly in the early postnatal period.…”

Section: Normal Ontogeny Of Bc and La Musclessupporting

confidence: 84%

“…Androgen treatment administered either prenatally or in the early postnatal period masculinizes the perineal musculature of female rats and mice through the early postnatal period (C ihá k et al, 1970;Park et al, 1999;Varela et al, 2000) and into adulthood (Breedlove and Arnold, 1983b;Sachs and Thomas, 1985;Wagner and Clemens, 1989b;Tobin and Joubert, 1991). Treatment of female rats with T prenatally or within a week of birth causes an increase in both the volume of the perineal muscles and the number and size of fibers in the LA (Breedlove and Arnold, 1983b;Tobin and Joubert, 1991;Varela et al, 2000).…”

Section: Androgen Treatment Of Femalesmentioning

confidence: 99%

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Normal ontogeny of perineal muscles and testosterone levels in Mongolian gerbils; Response to testosterone in developing females

Siegford¹,

Mansouri²,

Ulibarri³

2003

Anat. Rec.

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The spinal nucleus of the bulbocavernosus (SNB) of Mongolian gerbils (Meriones unguiculatus) becomes sexually dimorphic during postnatal life, rather than prenatally as in rats. We therefore examined the early postnatal ontogeny of Mongolian gerbils, focusing on growth, serum testosterone (T) levels, and the sexually dimorphic perineal musculature innervated by the SNB. Serum T levels were higher in males than in females from birth through adulthood, with several early postnatal peaks and a large increase in T occurring during puberty in males. The SNB target muscles-the bulbocavernosus (BC) and levator ani (LA)-were present in both sexes on postnatal day 1 (PND1). Cross-sectional areas of BC fibers in males increased with age, and concurrently the myofibers of the BC became more fully developed and organized. In PND10 female pups, the BC muscle was virtually absent, while the LA muscle remained (although it was reduced in size). Postnatal treatment of female gerbils with androgen caused the BC muscle to remain and the LA muscle to become larger by PND10. Sexual dimorphism of the SNB develops differently in gerbils compared to other species, although its target muscles appear to respond to androgen in a manner similar to that in rats. Anat Rec Part A 275A: 997-1008, 2003.

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Section: Normal Ontogeny Of Bc and La Musclessupporting

confidence: 86%

Section: Normal Ontogeny Of Bc and La Musclessupporting

confidence: 84%

Section: Androgen Treatment Of Femalesmentioning

confidence: 99%

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Normal ontogeny of perineal muscles and testosterone levels in Mongolian gerbils; Response to testosterone in developing females

Siegford¹,

Mansouri²,

Ulibarri³

2003

Anat. Rec.

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“…Most SNB motoneurons that survive the perinatal cell death period in female rats innervate the vestigial LA or the nondimorphic external anal sphincter (McKenna and Nadelhaft, 1986;Tobin and Joubert, 1988). Although the SNB neuromuscular system has been best studied in rats, the androgen dependence and developmental profile of the perineal muscles appears similar in mice (Wagner and Clemens, 1989;Forger et al, 1993;Park et al, 1999). Perineal muscle morphology is also altered by androgen manipulations during development in dogs, spotted hyenas, and gerbils (Forger and Breedlove, 1986;Forger et al, 1996;Siegford et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Effects of Bax Gene Deletion on Muscle and Motoneuron Degeneration in a Sexually Dimorphic Neuromuscular System

Jacob

Bengston²,

Forger³

2005

Journal of Neuroscience

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Motoneurons in the spinal nucleus of the bulbocavernosus (SNB) and their target muscles in the perineum, bulbocavernosus (BC), and levator ani (LA) normally degenerate in female rodents. Death of the motoneurons and muscles can be prevented by androgen treatments around the time of birth. To identify the intracellular mechanisms underlying hormone-dependent survival of this neuromuscular system, we examined mice with a targeted disruption of the pro-death gene Bax. SNB motoneuron number was increased in female Bax؊/؊ mice, whether measured using immunolabeling for a motoneuron-specific marker or retrograde labeling with the fluorescent tracer Fluoro-Gold. Based on retrograde tracing, the sex difference in SNB cell number is eliminated in Bax؊/؊ mice. Thus, Bax is required for sexually dimorphic motoneuron death in the SNB, and motoneurons rescued by Bax deletion project their axons to the periphery. Mean soma size in the SNB of Bax؊/؊ females is reduced, however, and there is a subpopulation of very small cells in the SNB of female knock-outs. In addition, the BC muscle was not identified in any female, regardless of Bax gene status. All females possessed a small LA muscle, and Bax deletion resulted in a tripling of LA fiber number in females. This increase was small, however, relative to the Ͼ50-fold sex difference in LA muscle fiber number. Thus, the sex difference in the perineal muscles is mostly unaffected by the absence of Bax protein, and SNB motoneuron number is dissociated from target muscle size in Bax؊/؊ animals.

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“…SNB and RDLN motoneurons were counted in alternate sections as in previous studies (Forger et al, 1997;Park et al, 1999). Only motoneurons with a clearly visible nucleus and nucleolus were included in the analysis; the SNB was counted bilaterally, and motoneurons in the RDLN were counted unilaterally.…”

Section: Methodsmentioning

confidence: 99%

Overexpression of Bcl-2 Reduces Sex Differences in Neuron Number in the Brain and Spinal Cord

Zup

Waters

et al. 2003

J. Neurosci.

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Several sex differences in the nervous system depend on differential cell death during development in males and females. The anti-apoptotic protein, Bcl-2, promotes the survival of many types of neurons during development and in response to injury. To determine whether Bcl-2 might similarly control cell death in sexually dimorphic regions, we compared neuron number in wild-type mice and transgenic mice overexpressing Bcl-2 under the control of a neuron-specific promoter. Three neural areas were examined: the spinal nucleus of the bulbocavernosus (SNB), in which neuron number is greater in males; the retrodorsolateral nucleus (RDLN) of the spinal cord, which exhibits no sex difference in neuron number; and the anteroventral periventricular nucleus (AVPV) of the hypothalamus, in which both overall cell density and the number of tyrosine hydroxylase immunoreactive (TH-ir) neurons are greater in females. Bcl-2 overexpression significantly increased SNB cell number in females, overall cell density of AVPV in males, and RDLN cell number in both sexes. Bcl-2 overexpression did not alter the number of TH-ir neurons in AVPV of males or females. These findings indicate that Bcl-2 can regulate sexually dimorphic cell number in the brain and spinal cord and suggest that Bcl-2 may mediate effects of testosterone on cell survival during neural development. In contrast to the regulation of overall cell density in AVPV, the sex difference in TH cell number apparently is not caused by a Bcl-2-dependent mechanism.

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Effects of testosterone on the development of a sexually dimorphic neuromuscular system in ciliary neurotrophic factor receptor knockout mice

Cited by 16 publications

References 49 publications

Normal ontogeny of perineal muscles and testosterone levels in Mongolian gerbils; Response to testosterone in developing females

Normal ontogeny of perineal muscles and testosterone levels in Mongolian gerbils; Response to testosterone in developing females

Effects of Bax Gene Deletion on Muscle and Motoneuron Degeneration in a Sexually Dimorphic Neuromuscular System

Overexpression of Bcl-2 Reduces Sex Differences in Neuron Number in the Brain and Spinal Cord

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