Role of the progesterone receptor in restrained glutamic acid decarboxylase gene expression in the hypothalamus during the preovulatory luteinizing hormone surge

Darrell W Brann, Richard Unda, Virendra B. Mahesh

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Previous work by our laboratory demonstrated that activation of the progesterone receptor through exogenous administration of progesterone suppressed glutamic acid decarboxylase-67 (GAD67) mRNA in the hypothalamus of the estrogen-primed ovariectomized rat. Since GAD67 is the major synthetic enzyme for the inhibitory transmitter, γ-aminobutyric acid, the finding raised the possibility that the endogenous activation of the progesterone receptor may act to restrain GAD67 expression during the natural preovulatory gonadotropin surge during proestrus in the rat, thereby allowing GnRH secretion and the resultant LH surge. To test this hypothesis, the progesterone receptor antagonist, RU486, was administered to regularly cycling proestrous rats and the effect on GAD67 and GAD65 mRNA levels in the preoptic area (POA) and medial basal hypothalamus (MBH) was examined. Serum luteinizing hormone (LH) levels were also examined in order to identify correlations between changes in POA and MBH GAD levels and production of the LH surge. GAD67 mRNA levels in the POA were increased in the cycling rat during proestrus at 18.00 h at the peak and just preceding the termination of the LH surge. There was no change in GAD67 mRNA levels in the MBH, and GAD65 expression was also unchanged during proestrus in the POA and MBH. Treatment with the anti-progestin RU486 resulted in an increase in GAD67 mRNA levels at 12.00 and 14.00 h in the POA, and in the MBH at 14.00, 16.00, and 18.00 h during proestrus, effects which preceded and correlated with the attenuated LH surge in RU486-treated rats at 18.00 h. GAD65 mRNA levels were also elevated by RU486 at 14.00 and 16.00 h in the POA, and at 14.00 h in the MBH during proestrus. These findings suggest that the progesterone receptor plays a role in restraining GAD expression in the hypothalamus during proestrus, and that this effect may be important for the production of the GnRH and LH surge.

Original languageEnglish (US)
Pages (from-to)283-289
Number of pages7
JournalNeuroendocrinology
Volume76
Issue number5
DOIs
StatePublished - Dec 12 2002

Fingerprint

Glutamate Decarboxylase
Middle Hypothalamus
Proestrus
Progesterone Receptors
Luteinizing Hormone
Preoptic Area
Hypothalamus
Gene Expression
Messenger RNA
Gonadotropin-Releasing Hormone
Aminobutyrates
Progestins
Gonadotropins
Progesterone
Estrogens
Enzymes
Serum

Keywords

  • Estrous cycle
  • Gamma-aminobutyric acid
  • Gonadal steroid receptors
  • Gonadal steroids
  • Gonadotropin releasing hormone
  • Gonadotropins
  • Preoptic area

ASJC Scopus subject areas

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

Cite this

Role of the progesterone receptor in restrained glutamic acid decarboxylase gene expression in the hypothalamus during the preovulatory luteinizing hormone surge. / Brann, Darrell W; Unda, Richard; Mahesh, Virendra B.

In: Neuroendocrinology, Vol. 76, No. 5, 12.12.2002, p. 283-289.

Research output: Contribution to journalArticle

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abstract = "Previous work by our laboratory demonstrated that activation of the progesterone receptor through exogenous administration of progesterone suppressed glutamic acid decarboxylase-67 (GAD67) mRNA in the hypothalamus of the estrogen-primed ovariectomized rat. Since GAD67 is the major synthetic enzyme for the inhibitory transmitter, γ-aminobutyric acid, the finding raised the possibility that the endogenous activation of the progesterone receptor may act to restrain GAD67 expression during the natural preovulatory gonadotropin surge during proestrus in the rat, thereby allowing GnRH secretion and the resultant LH surge. To test this hypothesis, the progesterone receptor antagonist, RU486, was administered to regularly cycling proestrous rats and the effect on GAD67 and GAD65 mRNA levels in the preoptic area (POA) and medial basal hypothalamus (MBH) was examined. Serum luteinizing hormone (LH) levels were also examined in order to identify correlations between changes in POA and MBH GAD levels and production of the LH surge. GAD67 mRNA levels in the POA were increased in the cycling rat during proestrus at 18.00 h at the peak and just preceding the termination of the LH surge. There was no change in GAD67 mRNA levels in the MBH, and GAD65 expression was also unchanged during proestrus in the POA and MBH. Treatment with the anti-progestin RU486 resulted in an increase in GAD67 mRNA levels at 12.00 and 14.00 h in the POA, and in the MBH at 14.00, 16.00, and 18.00 h during proestrus, effects which preceded and correlated with the attenuated LH surge in RU486-treated rats at 18.00 h. GAD65 mRNA levels were also elevated by RU486 at 14.00 and 16.00 h in the POA, and at 14.00 h in the MBH during proestrus. These findings suggest that the progesterone receptor plays a role in restraining GAD expression in the hypothalamus during proestrus, and that this effect may be important for the production of the GnRH and LH surge.",
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AB - Previous work by our laboratory demonstrated that activation of the progesterone receptor through exogenous administration of progesterone suppressed glutamic acid decarboxylase-67 (GAD67) mRNA in the hypothalamus of the estrogen-primed ovariectomized rat. Since GAD67 is the major synthetic enzyme for the inhibitory transmitter, γ-aminobutyric acid, the finding raised the possibility that the endogenous activation of the progesterone receptor may act to restrain GAD67 expression during the natural preovulatory gonadotropin surge during proestrus in the rat, thereby allowing GnRH secretion and the resultant LH surge. To test this hypothesis, the progesterone receptor antagonist, RU486, was administered to regularly cycling proestrous rats and the effect on GAD67 and GAD65 mRNA levels in the preoptic area (POA) and medial basal hypothalamus (MBH) was examined. Serum luteinizing hormone (LH) levels were also examined in order to identify correlations between changes in POA and MBH GAD levels and production of the LH surge. GAD67 mRNA levels in the POA were increased in the cycling rat during proestrus at 18.00 h at the peak and just preceding the termination of the LH surge. There was no change in GAD67 mRNA levels in the MBH, and GAD65 expression was also unchanged during proestrus in the POA and MBH. Treatment with the anti-progestin RU486 resulted in an increase in GAD67 mRNA levels at 12.00 and 14.00 h in the POA, and in the MBH at 14.00, 16.00, and 18.00 h during proestrus, effects which preceded and correlated with the attenuated LH surge in RU486-treated rats at 18.00 h. GAD65 mRNA levels were also elevated by RU486 at 14.00 and 16.00 h in the POA, and at 14.00 h in the MBH during proestrus. These findings suggest that the progesterone receptor plays a role in restraining GAD expression in the hypothalamus during proestrus, and that this effect may be important for the production of the GnRH and LH surge.

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