Neuroendocrine Regulation of GnRH and Behavior During Aging in Birds

Ottinger, Mary Ann; Thompson, Nichola; Viglietti‐Panzica, C.; Panzica, Giancarlo

doi:10.1016/s0361-9230(97)00228-1

Cited by 33 publications

(19 citation statements)

References 44 publications

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“…Male gonads make very little estrogen but some testosterone. To retain male brain organization, males need to convert testosterone to estrogen within the brain via aromatase activity (51). To retain female brain organization, females use their gonadal estrogens, as suggested in previous work with in ovo estrogen treatments (20), but shunt the production of additional estrogens in certain brain areas with high levels of steroid reductases in them.…”

Section: Discussionmentioning

confidence: 99%

Male Japanese quails with female brains do not show male sexual behaviors

Gahr

2003

Proc. Natl. Acad. Sci. U.S.A.

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During embryonic development, gonadal steroid hormones (androgens and estrogens) are thought to organize the sexual differentiation of the brain in the heterogametic sexes of higher vertebrates (males in mammals, females in birds). Brain differentiation of the homogametic sexes is thought to proceed by default, not requiring sex hormones for sex-specific organization. In gallinaceous birds such as the Japanese quail, female brain organization is thought to develop via estrogen-dependent demasculinization of a default male brain phenotype. We performed male donor-tofemale host (MF), female-to-male (FM), male-to-male (MM), and female-to-female (FF) isotopic, isochronic transplantation of the forebrain primordium in Japanese quail embryos before gonadal differentiation had occurred; brain chimeras had a forebrain (including the hypothalamus) originating exclusively from donor cells. MM, FF, and MF chimeras all showed sexual behavior governed by the genetic sex of the host. In contrast, FM chimeras (genetically female forebrain, all other tissues genetically male) showed no mounting and only rudimentary crowing behavior. Although MM, FF, MF, and FM chimeras all showed host-typical production of steroid hormones during embryonic life, only FM chimeras were hypogonadal, had atypical low levels of circulating testosterone in adulthood, and showed reduction (crowing) or absence (mounting) of reproductive behaviors. Morphological features of the medial preoptic nucleus (a sexually dimorphic brain area) also were not male-like in FM males. These data demonstrate a brain-intrinsic, genetically determined component that organizes the sex-typical production of gonadal hormones in adulthood and call for a reevaluation of the mechanisms underlying brain sexual differentiation in other higher-vertebrate species.

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Section: Discussionmentioning

confidence: 99%

Male Japanese quails with female brains do not show male sexual behaviors

Gahr

2003

Proc. Natl. Acad. Sci. U.S.A.

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“…When combined with results of extensive work on forebrain neuroendocrine mechanisms of sexual behavior in this species [Adkins-Regan, 1983, 1996Balthazart et al, 1996;Panzica et al, 1996;Ottinger et al, 1997], a fuller picture emerges of the neural system that leads to successful fertilization of the female. Interesting questions are raised about how the forebrain and spinal cord mechanisms are integrated and about the pathway by which the sight of a female leads to cloacal muscle movement.…”

Section: Discussionmentioning

confidence: 99%

“…This work is part of a continuing program of research to determine neuroendocrine mechanisms of reproductive behaviors in this species, an effort that thus far has focused on forebrain mechanisms [Adkins-Regan, 1983, 1996Balthazart et al, 1996;Ottinger et al, 1997;Panzica et al, 1996].…”

Section: Introductionmentioning

confidence: 99%

The Foam Production System of the Male Japanese Quail: Characterization of Structure and Function

1998

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The research described here characterizes a unique neuromuscular system involved in reproductive behavior – the foam production system of the male Japanese quail (Coturnix japonica). Male quail produce a large amount of foam that is transferred to the female during copulation, enhancing male fertilization success. The source is the foam gland complex, a large sexually dimorphic, androgen sensitive, external protuberance of the dorsal cloaca, consisting of glandular units interdigitated with striated muscle fibers of the sphincter cloacae muscle (mSC). Electromyographic (EMG) analysis of mSC activity in freely moving males interacting with females revealed different characteristics of the EMG signal during copulation, voiding of excreta, and other mSC movement. The amount of mSC activity and also the amount of foam produced were greatly increased by the presence of a female behind a screen. Denervation of mSC eliminated normal mSC movement and also abolished foam production, confirming that mSC activity is the mechanism for foam production. The spinal cord locations of the motoneurons innervating the major cloacal muscles, including mSC, were determined by injecting cholera-toxin conjugated horseradish peroxidase into each muscle. Labelled somata with multiple primary dendrites were located in Area IX of the lateral motor column of synsacral segments 7, 8, or 9 or 8, 9, and 10. The motoneurons serving mSC were intermingled with those projecting to the other cloacal muscles, but there were differences in the rostral-caudal placement of these neural populations. Thus mSC activity is an integral part of the male’s reproductive behavior, mSC activity can be socially stimulated, and mSC activity occurring in anticipation of copulation is likely to be functionally significant. Continued investigation of this highly accessible system has the potential to shed light on the mechanisms by which complex motor acts are produced and hormonally regulated.

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“…The pattern of GnRH-I release is pulsatile and neuropeptides, neurotransmitters, and steroid hormones modulate amplitude and in some cases frequency of release (Li et al, 1994a, b;Ottinger et al, 1997). During aging, the releasable pool of GnRH-I decreases in both males and fe-males in spite of little change in number of cells in females Ottinger et al, unpublished data).…”

Section: Elements Of Reproductive Aging In a Short-lived Avian Modelmentioning

confidence: 99%

Neuroendocrine and immune characteristics of aging in avian species

Ottinger¹,

Lavoie²

2007

Cytogenet Genome Res

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Avian species show a remarkable diversity in lifespan. The differing lifespan patterns are found across a number of birds, in spite of higher body temperature and apparent increased metabolic rate. These characteristics make study of age-related changes of great interest, especially for understanding the biology of aging associated with surprisingly long lifespan in some birds. Our studies have focused on a short-lived avian model, the Japanese quail in order to describe reproductive aging and the neuroendocrine characteristics leading to reproductive senescence. Biomarkers of aging used in mammalian species include telomere length, oxidative damage, and selected metabolic indicators. These markers provide confirming evidence that the long-lived birds appear to age more slowly. A corollary area of interest is that of immune function and aging. Immune responses have been studied in selected wild birds and there has been a range of studies that have considered the effects of stress in wild and domestic species. Our laboratory studies have specifically tested response to immune challenge relative to aging in the quail model and these studies indicate that there is an age-related change in the qualitative aspects of the response. However, there are also intriguing differences in the ability of the aging quail to respond that differ from mammalian data. Finally, another approach to understanding aging is to attempt to develop or test strategies that may extend lifespan and presumably health. One area of great interest has been to consider the effect of calorie restriction, which is a treatment shown to extend lifespan in a variety of species. This approach is routinely used in domestic poultry as a means for extending reproductive function and enhancing health. Our data indicate that moderate calorie restriction has beneficial effects, and that physiological and endocrine responses reflect these benefits.

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Neuroendocrine Regulation of GnRH and Behavior During Aging in Birds

Cited by 33 publications

References 44 publications

Male Japanese quails with female brains do not show male sexual behaviors

Male Japanese quails with female brains do not show male sexual behaviors

The Foam Production System of the Male Japanese Quail: Characterization of Structure and Function

Neuroendocrine and immune characteristics of aging in avian species

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