Rostral medial preoptic area lesions' influence on female estrous processes and LHRH distribution

Popolow, Herbert B.; King, Joan C.; Gerall, Arnold A.

doi:10.1016/0031-9384(81)90053-6

Cited by 33 publications

(19 citation statements)

References 25 publications

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“…All of the fe males treated with TP on the 5th day of life failed to show a phasic secretion of LH in response to estrogen and proges terone treatment. This failure to show a positive feedback response to ovarian steroids was also found in animals with discrete lesions of the AVPv [62], Since the lesions did not encoroach upon the GnRH system [41,53], it appears that ablation of the AVPv eliminated a key neural element in volved in the mediation of steroid effects on phasic gonado tropin secretion. The sexually dimorphic dopaminergic cell group in this nucleus, which is at least greatly reduced in both the lesioned and androgen-sterilized animals, may be just such a neural element.…”

Section: Discussionmentioning

confidence: 88%

Influence of Perinatal Androgen on the Sexually Dimorphic Distribution of Tyrosine Hydroxylase-Immunoreactive Cells and Fibers in the Anteroventral Periventricular Nucleus of the Rat

Simerly¹,

Swanson

Handa³

et al. 1985

Neuroendocrinology

178

107

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Recently we reported that the anteroventral periventricular nucleus (AVPv) of the preoptic region contains a dramatic sexual dimorphism in the distribution of tyrosine hydroxylase- (TH-)immunoreactive cells and fibers in the rat. This sexual dimorphism appears to be due to a greater density of dopaminergic fibers, and a larger number of dopaminergic cell bodies, in the AVPv of the female. In the present study we used an indirect immunohistochemical method to evaluate the distribution of TH-immunoreactive cell bodies and fibers, and of dopamine-β-hydroxylase-(DBH-)stained fibers, in the AVPv of female rats that were treated with testosterone propionate (TP) perinatally or postnatally, or were left untreated. All of the postnatally TP-treated animals failed to show a phasic pattern of luteinizing hormone (LH) secretion in response to estrogen and progesterone injections. Both the perinatally and postnatally TP-treated females had polyfollicular ovaries that lacked corpora lutea at the time of gonadectomy. Perinatal TP exposure resulted in what appears to be a complete masculinization of both the number of TH-stained cells and the density of TH-stained fibers in the AVPv. The number of TH-stained cells in the postnatally TP-treated females was also completely masculinized, although the density of TH-stained fibers did not appear to be altered significantly. Gonadectomy resulted in a moderate increase in the density of TH-stained fibers in adult males, and did not significantly affect the fiber density in females, or the number of TH-stained cells in either sex. The distribution of DBH-stained fibers in the AVPv did not appear to be altered in any of the treatment groups. These results suggest that the distribution of dopaminergic fibers in the AVPv may be sensitive to testosterone levels in the adult male, and that although the critical period for the development of this fiber distribution may begin in the prenatal period, the number of dopaminergic cells in the AVPv can be completely sex reversed by a single postnatal dose of TP that appears to correlate with a permanent disruption of the normal pattern of gonadotropin secretion.

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Section: Discussionmentioning

confidence: 88%

Influence of Perinatal Androgen on the Sexually Dimorphic Distribution of Tyrosine Hydroxylase-Immunoreactive Cells and Fibers in the Anteroventral Periventricular Nucleus of the Rat

Simerly¹,

Swanson

Handa³

et al. 1985

Neuroendocrinology

178

107

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“…A particularly important and sexually dimorphic part of neural circuits that regulate the secretion of LH is the anteroventral periventricular nucleus of the preoptic region (AVPV). The AVPV has been shown to play a critical role in transducing hormonal feedback on LH secretion and is required for spontaneous ovulation (8,9). Consistent with this functional role, the AVPV contains high densities of neurons that express receptors for estrogen and progesterone (10) and implants of antiestrogens cause significant changes in LH secretion (11).…”

mentioning

confidence: 76%

Estrogen receptor-dependent sexual differentiation of dopaminergic neurons in the preoptic region of the mouse

Simerly

Zee

Pendleton

et al. 1997

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

190

141

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Although it has been known for some time that estrogen exerts a profound inf luence on brain development a definitive demonstration of the role of the classical estrogen receptor (ER␣) in sexual differentiation has remained elusive. In the present study we used a sexually dimorphic population of dopaminergic neurons in the anteroventral periventricular nucleus of the hypothalamus (AVPV) to test the dependence of sexual differentiation on a functional ER␣ by comparing the number of tyrosine hydroxylase (TH)-immunoreactive neurons in the AVPV of wild-type (WT) mice with that of mice in which the ER␣ had been disrupted by homologous recombination (ERKO␣). Only a few ER␣-immunoreactive neurons were detected in the AVPV of ERKO␣ mice, and the number of TH-immunoreactive neurons was three times that of WT mice, suggesting that disruption of the ER␣ gene feminized the number of THimmunoreactive neurons. In contrast, the AVPV contains the same number of TH-immunoreactive neurons in testicular feminized male mice as in WT males, indicating that sexual differentiation of this population of neurons is not dependent on an intact androgen receptor. The number of THimmunoreactive neurons in the AVPV of female ERKO␣ mice remained higher than that of WT males, but TH staining appeared to be lower than that of WT females. Thus, the sexual differentiation of dopamine neurons in the AVPV appears to be receptor specific and dependent on the perinatal steroid environment.From an evolutionary perspective, the most adaptive physiological responses are those that ensure successful reproduction. Coordinated sex-specific behaviors and physiological mechanisms have evolved to facilitate reproduction and it is now clear that most are determined by the central action of steroid hormones during brain development. For example, only female rats display a massive surge in gonadotropin secretion in response to treatment of gonadectomized animals with estrogen and progesterone, and exposure of genetic females to high levels of gonadal hormones such as testosterone near the time of birth results in defeminization of the sexually dimorphic pattern of luteinizing hormone (LH) secretion that triggers ovulation (1-4). Abundant evidence from a variety of animal models indicates that steroid hormones secreted by the gonads during development cause profound sex-specific changes in the structure and neurochemistry of certain forebrain regions, including sexually dimorphic regions in the hypothalamus thought to play key roles in mediating the preovulatory secretion of LH (4-7). A particularly important and sexually dimorphic part of neural circuits that regulate the secretion of LH is the anteroventral periventricular nucleus of the preoptic region (AVPV). The AVPV has been shown to play a critical role in transducing hormonal feedback on LH secretion and is required for spontaneous ovulation (8, 9). Consistent with this functional role, the AVPV contains high densities of neurons that express receptors for estrogen and progesterone (10) and implan...

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“…Immunocytochemical studies have revealed, however, that the majority of the perikarya of LHRH neurons are located in the preoptic and suprachiasmatic regions (Setalo et al, 1976;King et al, 1982;Hoffman and Gibbs, 1982 This coincidence indicated that the effect of anterior deafferentations or lesions of the preoptic area in inducing persistent estrus might be due to impairment of the LHRH neurosecretory neurons. Indeed, anterior deafferentations of the MBH (Merchenthaler et al, 1980a) or lesions of the ventral part of the preoptic area (Ibata et al, 1979;Popolow et al, 1981;Krey and Silverman, 1981) reduced the concentration of immunoreactive LHRH fibers in the median eminence, although it should be noted that a substantial proportion of the fibers were spared.…”

Section: Discussionmentioning

confidence: 99%

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

Terasawa¹,

Davis²

1983

Endocrinol Japon

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Previously we have found that small lesions confined to the medial preoptic nucleus (MPN) or the suprachiasmatic nucleus (SCN) blocked the cyclic release of gonadotropins in the female rat, inducing a persistent estrous state. Since the MPN is located just caudal to the organum vasculosum of the lamina terminalis (OVLT) where LHRH cell bodies are most concentrated, we applied an immunocytochemical technique to examine the possibility that the lesions had simply disrupted LHRH neurons or fibers.Using a new anti-LHRH provided by Dr. V. D. Ramirez, we found that the distribution pattern of immunoreactive LHRH cell bodies and fibers was similar to that previously reported, although the staining was more intense and extensive with low background.There was no concentration of LHRH cell bodies and fibers in the MPN or SCN and, in fact, these nuclei generally showed a lower density of stained elements than did sorrounding tissue. In persistent estrous animals with lesions confined to the MPN there was no detectable reduction of staind fibers in the median eminence.These results, along with the results of other workers, suggest that persistent estrus following lesions of the MPN or SCN is not due to reduction of LHRH neurons or fibers. Rather, they support the hypothesis that these nuclei are critical for triggering the ovulatory release of LHRH.

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Rostral medial preoptic area lesions' influence on female estrous processes and LHRH distribution

Cited by 33 publications

References 25 publications

Influence of Perinatal Androgen on the Sexually Dimorphic Distribution of Tyrosine Hydroxylase-Immunoreactive Cells and Fibers in the Anteroventral Periventricular Nucleus of the Rat

Influence of Perinatal Androgen on the Sexually Dimorphic Distribution of Tyrosine Hydroxylase-Immunoreactive Cells and Fibers in the Anteroventral Periventricular Nucleus of the Rat

Estrogen receptor-dependent sexual differentiation of dopaminergic neurons in the preoptic region of the mouse

The LHRH neuronal system in female rats: Relation to the medial preoptic nucleus.

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