Opposite changes of pituitary and ovarian receptors for lhrh in ageing rats

Further evidence for a direct neural control of ovarian lhrh receptor activity

Bianca Marchetti, Matteo Cioni

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15 Citations (Scopus)

Abstract

Hypophyseal and ovarian receptors for the neurohormone LHRH (LHRH-R) have been measured in young (3-4 months), middle-aged (8-11 months), constant estrous (CE, 10-14 months) and pseudopregnant (PR, 16-18 months) rats in order to study whether changes in hypothalamic and/or peripheral LHRH-like peptide production might precede and/or accompany the onset of reproductive failure observed in aging rats. Furthermore, we have investigated whether the neural efferent system from the brain to the ovary is affected with aging. The pattern of pituitary LHRH-R modifications during the estrous cycle of middle-aged rats shows lower LHRH-R levels on the second day of diestrus, resulting in a shift of the maximal LHRH binding capacity in the morning of proestrus. On the other hand, when comparing pituitary LHRH-R of animals exhibiting constant vaginal cornification (CVC) or repetitive PP with young estrus rats, no significant difference could be observed. Young rats responded to electrical stimulation (ES) of the medial preoptic area with an acute elevation of LHRH-R while ES performed in CVC, or PP animals resulted in a significant increase of hypophyseal LHRH binding capacity similar to the one observed in young estrous controls, indicating an impairment in the neural signals impinging in the pulse generating system, in old rats, and not an intrinsic defect of the LHRH-R per se. Ovarian LHRH-R concentration is higher in middle-aged cycling animals on the day of vaginal proestrus, compared to levels measured in young animals at any phase of the estrous cycle. Similarly, CE rats displaying CVC as well as PP animals show significantly higher numbers of LHRH-R with no change in affinity, than young estrus rats. CVC and PP rats receiving unilaterally an intraovarian injection of the potent LHRH antagonist, Ac-D-Cl-Phe1-2, D-Trp3, D-Phe6, D-Ala10, LHRH, showed an acute drop of LHRH-R measured within the treated ovary with no significant changes taking place in the vehicle-treated contralateral gland, suggesting that changes of endogenous ovarian LHRH-like peptide might participate in the mechanism(s) responsible for LHRH receptor increase observed in aging rats. In order to investigate the participation of a direct neural efferent pathway in ovarian LHRH-R regulation, young and old rats were subjected to spinal cord transection (above T10-T11). Bilateral transection of the spinal cord in young animals in the morning of proestrous markedly increased ovarian LHRH-R concentration in the afternoon (17.00 h) of the same day. When spinalectomy was performed unilaterally, a marked increase of ovarian LHRH-R capacity in the gonad ipsilateral to the intervention was measured, with no effect taking place in the contralateral gland. On the other hand, the same intervention did not modify the already stimulated LHRH-R levels measured in old rats. It is suggested that an increase of ovarian LHRH-R activity might trigger the neuroEndoerine mechanisms leading to reproductive dysfunction in aging female rats. Furthermore, present data also suggest that the establishment of a central defect in aging animals might directly interfere with ovarian function, by means of a neural signal, modulating ovarian LHRH-R activity, which further reinforces our view that the brain and the gonads can directly communicate via a neural pathway.

Original languageEnglish
Pages (from-to)242-251
Number of pages10
JournalNeuroendocrinology
Volume48
Issue number3
DOIs
Publication statusPublished - 1988

Fingerprint

Gonadotropin-Releasing Hormone
LHRH Receptors
Proestrus
Neural Pathways
Estrous Cycle
Estrus
Gonads
Spinal Cord Injuries
Electric Stimulation
Ovary
Efferent Pathways
Diestrus
Preoptic Area
Brain

Keywords

  • Ageing
  • Central and peripheral
  • LHRH
  • Medial preoptic area
  • Ovarian innervation
  • Ovary
  • Pathway neural
  • Pituitary
  • Receptors, LHRH
  • Spinal cord

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism
  • Cellular and Molecular Neuroscience
  • Endocrine and Autonomic Systems
  • Neuroscience(all)

Cite this

@article{bf67bd82e202413bb00cc095809b5b91,
title = "Opposite changes of pituitary and ovarian receptors for lhrh in ageing rats: Further evidence for a direct neural control of ovarian lhrh receptor activity",
abstract = "Hypophyseal and ovarian receptors for the neurohormone LHRH (LHRH-R) have been measured in young (3-4 months), middle-aged (8-11 months), constant estrous (CE, 10-14 months) and pseudopregnant (PR, 16-18 months) rats in order to study whether changes in hypothalamic and/or peripheral LHRH-like peptide production might precede and/or accompany the onset of reproductive failure observed in aging rats. Furthermore, we have investigated whether the neural efferent system from the brain to the ovary is affected with aging. The pattern of pituitary LHRH-R modifications during the estrous cycle of middle-aged rats shows lower LHRH-R levels on the second day of diestrus, resulting in a shift of the maximal LHRH binding capacity in the morning of proestrus. On the other hand, when comparing pituitary LHRH-R of animals exhibiting constant vaginal cornification (CVC) or repetitive PP with young estrus rats, no significant difference could be observed. Young rats responded to electrical stimulation (ES) of the medial preoptic area with an acute elevation of LHRH-R while ES performed in CVC, or PP animals resulted in a significant increase of hypophyseal LHRH binding capacity similar to the one observed in young estrous controls, indicating an impairment in the neural signals impinging in the pulse generating system, in old rats, and not an intrinsic defect of the LHRH-R per se. Ovarian LHRH-R concentration is higher in middle-aged cycling animals on the day of vaginal proestrus, compared to levels measured in young animals at any phase of the estrous cycle. Similarly, CE rats displaying CVC as well as PP animals show significantly higher numbers of LHRH-R with no change in affinity, than young estrus rats. CVC and PP rats receiving unilaterally an intraovarian injection of the potent LHRH antagonist, Ac-D-Cl-Phe1-2, D-Trp3, D-Phe6, D-Ala10, LHRH, showed an acute drop of LHRH-R measured within the treated ovary with no significant changes taking place in the vehicle-treated contralateral gland, suggesting that changes of endogenous ovarian LHRH-like peptide might participate in the mechanism(s) responsible for LHRH receptor increase observed in aging rats. In order to investigate the participation of a direct neural efferent pathway in ovarian LHRH-R regulation, young and old rats were subjected to spinal cord transection (above T10-T11). Bilateral transection of the spinal cord in young animals in the morning of proestrous markedly increased ovarian LHRH-R concentration in the afternoon (17.00 h) of the same day. When spinalectomy was performed unilaterally, a marked increase of ovarian LHRH-R capacity in the gonad ipsilateral to the intervention was measured, with no effect taking place in the contralateral gland. On the other hand, the same intervention did not modify the already stimulated LHRH-R levels measured in old rats. It is suggested that an increase of ovarian LHRH-R activity might trigger the neuroEndoerine mechanisms leading to reproductive dysfunction in aging female rats. Furthermore, present data also suggest that the establishment of a central defect in aging animals might directly interfere with ovarian function, by means of a neural signal, modulating ovarian LHRH-R activity, which further reinforces our view that the brain and the gonads can directly communicate via a neural pathway.",
keywords = "Ageing, Central and peripheral, LHRH, Medial preoptic area, Ovarian innervation, Ovary, Pathway neural, Pituitary, Receptors, LHRH, Spinal cord",
author = "Bianca Marchetti and Matteo Cioni",
year = "1988",
doi = "10.1159/000125018",
language = "English",
volume = "48",
pages = "242--251",
journal = "Neuroendocrinology",
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TY - JOUR

T1 - Opposite changes of pituitary and ovarian receptors for lhrh in ageing rats

T2 - Further evidence for a direct neural control of ovarian lhrh receptor activity

AU - Marchetti, Bianca

AU - Cioni, Matteo

PY - 1988

Y1 - 1988

N2 - Hypophyseal and ovarian receptors for the neurohormone LHRH (LHRH-R) have been measured in young (3-4 months), middle-aged (8-11 months), constant estrous (CE, 10-14 months) and pseudopregnant (PR, 16-18 months) rats in order to study whether changes in hypothalamic and/or peripheral LHRH-like peptide production might precede and/or accompany the onset of reproductive failure observed in aging rats. Furthermore, we have investigated whether the neural efferent system from the brain to the ovary is affected with aging. The pattern of pituitary LHRH-R modifications during the estrous cycle of middle-aged rats shows lower LHRH-R levels on the second day of diestrus, resulting in a shift of the maximal LHRH binding capacity in the morning of proestrus. On the other hand, when comparing pituitary LHRH-R of animals exhibiting constant vaginal cornification (CVC) or repetitive PP with young estrus rats, no significant difference could be observed. Young rats responded to electrical stimulation (ES) of the medial preoptic area with an acute elevation of LHRH-R while ES performed in CVC, or PP animals resulted in a significant increase of hypophyseal LHRH binding capacity similar to the one observed in young estrous controls, indicating an impairment in the neural signals impinging in the pulse generating system, in old rats, and not an intrinsic defect of the LHRH-R per se. Ovarian LHRH-R concentration is higher in middle-aged cycling animals on the day of vaginal proestrus, compared to levels measured in young animals at any phase of the estrous cycle. Similarly, CE rats displaying CVC as well as PP animals show significantly higher numbers of LHRH-R with no change in affinity, than young estrus rats. CVC and PP rats receiving unilaterally an intraovarian injection of the potent LHRH antagonist, Ac-D-Cl-Phe1-2, D-Trp3, D-Phe6, D-Ala10, LHRH, showed an acute drop of LHRH-R measured within the treated ovary with no significant changes taking place in the vehicle-treated contralateral gland, suggesting that changes of endogenous ovarian LHRH-like peptide might participate in the mechanism(s) responsible for LHRH receptor increase observed in aging rats. In order to investigate the participation of a direct neural efferent pathway in ovarian LHRH-R regulation, young and old rats were subjected to spinal cord transection (above T10-T11). Bilateral transection of the spinal cord in young animals in the morning of proestrous markedly increased ovarian LHRH-R concentration in the afternoon (17.00 h) of the same day. When spinalectomy was performed unilaterally, a marked increase of ovarian LHRH-R capacity in the gonad ipsilateral to the intervention was measured, with no effect taking place in the contralateral gland. On the other hand, the same intervention did not modify the already stimulated LHRH-R levels measured in old rats. It is suggested that an increase of ovarian LHRH-R activity might trigger the neuroEndoerine mechanisms leading to reproductive dysfunction in aging female rats. Furthermore, present data also suggest that the establishment of a central defect in aging animals might directly interfere with ovarian function, by means of a neural signal, modulating ovarian LHRH-R activity, which further reinforces our view that the brain and the gonads can directly communicate via a neural pathway.

AB - Hypophyseal and ovarian receptors for the neurohormone LHRH (LHRH-R) have been measured in young (3-4 months), middle-aged (8-11 months), constant estrous (CE, 10-14 months) and pseudopregnant (PR, 16-18 months) rats in order to study whether changes in hypothalamic and/or peripheral LHRH-like peptide production might precede and/or accompany the onset of reproductive failure observed in aging rats. Furthermore, we have investigated whether the neural efferent system from the brain to the ovary is affected with aging. The pattern of pituitary LHRH-R modifications during the estrous cycle of middle-aged rats shows lower LHRH-R levels on the second day of diestrus, resulting in a shift of the maximal LHRH binding capacity in the morning of proestrus. On the other hand, when comparing pituitary LHRH-R of animals exhibiting constant vaginal cornification (CVC) or repetitive PP with young estrus rats, no significant difference could be observed. Young rats responded to electrical stimulation (ES) of the medial preoptic area with an acute elevation of LHRH-R while ES performed in CVC, or PP animals resulted in a significant increase of hypophyseal LHRH binding capacity similar to the one observed in young estrous controls, indicating an impairment in the neural signals impinging in the pulse generating system, in old rats, and not an intrinsic defect of the LHRH-R per se. Ovarian LHRH-R concentration is higher in middle-aged cycling animals on the day of vaginal proestrus, compared to levels measured in young animals at any phase of the estrous cycle. Similarly, CE rats displaying CVC as well as PP animals show significantly higher numbers of LHRH-R with no change in affinity, than young estrus rats. CVC and PP rats receiving unilaterally an intraovarian injection of the potent LHRH antagonist, Ac-D-Cl-Phe1-2, D-Trp3, D-Phe6, D-Ala10, LHRH, showed an acute drop of LHRH-R measured within the treated ovary with no significant changes taking place in the vehicle-treated contralateral gland, suggesting that changes of endogenous ovarian LHRH-like peptide might participate in the mechanism(s) responsible for LHRH receptor increase observed in aging rats. In order to investigate the participation of a direct neural efferent pathway in ovarian LHRH-R regulation, young and old rats were subjected to spinal cord transection (above T10-T11). Bilateral transection of the spinal cord in young animals in the morning of proestrous markedly increased ovarian LHRH-R concentration in the afternoon (17.00 h) of the same day. When spinalectomy was performed unilaterally, a marked increase of ovarian LHRH-R capacity in the gonad ipsilateral to the intervention was measured, with no effect taking place in the contralateral gland. On the other hand, the same intervention did not modify the already stimulated LHRH-R levels measured in old rats. It is suggested that an increase of ovarian LHRH-R activity might trigger the neuroEndoerine mechanisms leading to reproductive dysfunction in aging female rats. Furthermore, present data also suggest that the establishment of a central defect in aging animals might directly interfere with ovarian function, by means of a neural signal, modulating ovarian LHRH-R activity, which further reinforces our view that the brain and the gonads can directly communicate via a neural pathway.

KW - Ageing

KW - Central and peripheral

KW - LHRH

KW - Medial preoptic area

KW - Ovarian innervation

KW - Ovary

KW - Pathway neural

KW - Pituitary

KW - Receptors, LHRH

KW - Spinal cord

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U2 - 10.1159/000125018

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EP - 251

JO - Neuroendocrinology

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