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Effect of Interleukin‐1β on Gonadotropin‐Releasing Hormone (GnRH) and GnRH Receptor Gene Expression in Castrated Male Rats
Author(s) -
Alice Kang,
Ki Wook Kim,
Leonhardt,
Jarry,
Wuttke
Publication year - 2000
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1046/j.1365-2826.2000.00466.x
Subject(s) - medicine , endocrinology , preoptic area , gonadotropin releasing hormone , hypothalamus , gnrhr , biology , luteinizing hormone , anterior pituitary , hormone
Increasing evidence suggests that interleukin‐1 β (IL‐1 β ) regulates luteinizing hormone (LH) release primarily through modulation of the gonadotropin‐releasing hormone (GnRH) neuronal activity. This study was undertaken to elucidate the effect of IL‐1 β on GnRH as well as GnRH receptor (GnRHR) gene expression in the preoptic area. IL‐1 β (100 ng/rat) or saline was administered into the lateral ventricle of castrated rats. RNA samples were isolated from micropunches of the preoptic area and mediobasal hypothalamus from individual brain slices and GnRH mRNA levels in the preoptic area and GnRHR mRNA levels in the mediobasal hypothalamus were determined by competitive reverse transcription‐polymerase chain reaction (RT‐PCR) protocols. Serum LH concentrations were decreased from 1 h to 3 h after IL‐1 β treatment, but rebounded at 5 h, while serum concentrations of follicle‐stimulating hormone (FSH) and prolactin were not altered. There were no significant changes in GnRH mRNA levels from the micropunched preoptic area, while GnRHR mRNA levels from the preoptic area and mediobasal hypothalamus micropunch samples, but not in the anterior pituitary, showed a pattern similar to the serum LH profile following i.c.v. administration of IL‐1 β . We then examined the effect of IL‐1 β on the translational efficiency of the GnRH mRNA. After the separation and fractionation of polyribosome‐associated cytoplasmic RNA from the hypothalamic fragments containing the preoptic area‐anterior hypothalamic area of control (saline‐treated) and IL‐1 β ‐treated group 3 h after administration, GnRH transcript levels were examined from the each fraction. IL‐1 β decreased the translational efficiency of the transcribed GnRH mRNA. These results clearly demonstrate that central administration of IL‐1 β suppresses the translational activity of GnRH mRNA. Moreover, GnRHR may play an important role in the modulation of GnRH neuronal activity through GnRHR‐expressing neurones (or glia) in the hypothalamus.