AMPA glutamate receptor subunits in the guinea pig hypothalamus: Distribution and colocalization with progesterone receptor

Abstract

Excitatory amino acids (EAAs), particularly glutamate, have been implicated in the control of luteinizing hormone (LH) secretion through facilitation of gonadotropin-releasing hormone release. The effects of EAAs are mediated by means of ionotropic glutamate receptors, which are divided into N-methyl-D-aspartate (NMDA) and non-NMDA (kainate and AMPA) subtypes. Moreover, ovarian steroids are responsible for inducing the preovulatory surge of LH and are involved in the actions of EAAs on LH release. Progesterone is directly involved in the potentiating effect of ovarian steroids on the stimulating effect of AMPA neurotransmission on gonadotropin secretion. To broaden our understanding of the role of hypothalamic AMPA receptors in the steroid-induced LH surge, we determined the cellular localization of AMPA receptors in the hypothalamus of guinea pigs by using antibodies that recognize the GluR1, GluR2, GluR2/3, or GluR4 subunits, and then we examined the neuroanatomic relationships between these receptors and the progesterone receptor (PR). Different patterns of immunostaining within the preoptic area and hypothalamus were evident with the antibodies to the four subunits with marked contrasts between moderate staining for GluR1, intensely stained structures for GluR2 and GluR2/3, and little specific staining for GluR4. Immunoreactive (IR) neurons were visualized in many regions, including the two regions known to contain a dense population of estradiol-induced PR-IR cells: the preoptic periventricular and ventrolateral hypothalamic nuclei. Approximately 60% of GluR1-IR and 39% of GluR2-IR cells in the preoptic region possessed PR, whereas 46% of GluR1-IR and 54% of GluR2-IR cells in the ventrolateral nucleus expressed PR. These neuroanatomic results suggest that the coordinated actions of progesterone and glutamatergic inputs on mammalian reproductive functions are integrated at the cellular level.

Glutamate in Male and Female Sexual Behavior: Receptors, Transporters, and Steroid Independence

“…In terms of the progesterone receptor, only one study appeared to show possible interactions with glutamate. This study demonstrated that AMPA receptor colocalized with the progesterone receptor in guinea pig hypothalamus (Warembourg and Leroy, 2002).…”

AMPA, kainate, and NMDA receptor densities in the hippocampus of untreated male rats and females in estrus and diestrus

“…In addition, the observed fluctuation in AMPA binding densities could be a result of an AMPA receptor translocation from intracellular inactive stores specially known for this receptor (Kullmann, 1994;Hall and Soderling, 1997) to the cell surface, where it becomes functional (Hall and Soderling, 1997;Shi et al, 1999). Moreover, variations in AMPA receptor densities could also be due to estradiol-induced changes in progesterone receptor densities, since a colocalization of AMPA receptor subunits and the progesterone receptor has recently been described in the guinea pig brain (Warembourg and Leroy, 2002). These known rapid AMPA receptor fluctuations indicate that AMPA receptor densities are more variable than the NMDA receptor system.…”

Effects of nonylphenol on endocrine regulation-associated gene expression profiles in whole brain of F1 generation male rats

“…AMPA type glutamate receptor mediates rapid excitatory synapse transmission, which is mainly permeable for Na þ , rather than Ca 2þ (Zhang et al 2006). Warembourg and Leroy (2002) reported that essential amino acid, particularly glutamate, was implicated in the control of luteinizing hormone (LH) secretion through facilitation of gonadotropin-releasing hormone release. LH mainly promotes Leydig cells of the adult testis to synthesize testosterone.…”