Interplay between the endocannabinoid system and GnRH-I in the forebrain of the anuran amphibian Rana esculenta.
The morphofunctional relationship between the endocannabinoid system and GnRH activity in the regulation of reproduction has poorly been investigated in vertebrates. Due to the anatomical features of lower vertebrate brain, in the present paper, we chose the frog Rana esculenta (anuran amphibian) as a suitable model to better investigate such aspects of the reproductive physiology. By using double-labeling immunofluorescence aided with a laser-scanning confocal microscope, we found a subpopulation of the frog hypothalamic GnRH neurons endowed with CB1 cannabinoid receptors. By means of semiquantitative RT-PCR assay, we have shown that, during the annual sexual cycle, GnRH-I mRNA (formerly known as mammalian GnRH) and CB1 mRNA have opposite expression profiles in the brain. In particular, this occurs in telencephalon and diencephalon, the areas mainly involved in GnRH release and control of the reproduction. Furthermore, we found that the endocannabinoid anandamide is able to inhibit GnRH-I mRNA synthesis; buserelin (a GnRH agonist), in turn, inhibits the synthesis of GnRH-I mRNA and induces an increase of CB1 transcription. Our observations point out the occurrence of a morphofunctional anatomical basis to explain a reciprocal relationship between the endocannabinoid system and GnRH neuronal activity.
Meccariello
Rosaria
R
Dipartimento di Studi delle Istituzioni e dei Sistemi Territoriali, Università di Napoli Parthenope, 80133 Napoli, Italy.
Franzoni
Maria Fosca
MF
Chianese
Rosanna
R
Cottone
Erika
E
Scarpa
Donatella
D
Donna
Daniela
D
Cobellis
Gilda
G
Guastalla
Alda
A
Pierantoni
Riccardo
R
Fasano
Silvia
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002064:Buserelin / Q000494:pharmacology; D063385:Cannabinoid Receptor Modulators / Q000378:metabolism / Q000502:physiology*; D003001:Cloning, Molecular; D063388:Endocannabinoids; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D016548:Prosencephalon / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011893:Rana esculenta / Q000378:metabolism / Q000502:physiology*; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism / Q000502:physiology*; D012098:Reproduction / Q000235:genetics; D017386:Sequence Homology, Amino Acid
D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D012333:RNA, Messenger; D043884:Receptor, Cannabinoid, CB1; D007987:Gonadotropin-Releasing Hormone; D002064:Buserelin