Infertility in GABAB1KO Female Mice: Possible Role of Brain Estrogens and Hypothalamic Response to Kisspeptin

NOELIA PAULA DI GIORGIO, ; PAULA V LÓPEZ; NADIA BOURGUIGNON; SHEILA J SEMAAN; BERNHARD BETTLER; ALEXANDER S KAUFFMAN; CARLOS LIBERTUN; VICTORIA ADELA LUX-LANTOS

Chicago, ILL

Congreso; The Endocrine Society (USA). 96th Annual Meeting XVI International Congress of Endocrinology.; 2014

The Endocrine Society (USA).

Abstract #13932 Infertility in GABAB1KO Female Mice: Possible Role of Brain Estrogens and Hypothalamic Response to Kisspeptin Noelia Paula Di Giorgio, PhD1, Paula V López1, Nadia Bourguignon, Msc1, Sheila J Semaan, PhD2, Bernhard Bettler, PhD3, Alexander S Kauffman, PhD2, Carlos Libertun, MD, PhD1 and Victoria Adela Lux-Lantos, PhD1, (1)Neuroendocrinology, Instituto de Biologia y Medicina Experimental-CONICET, Buenos Aires, Argentina, (2)Dept. of Reproductive Medicine, University of California San Diego, La Jolla, CA, (3)Dept of Biomedicine, Univ. of Basel, Basel, Switzerland Adult GABAB1KO (KO) female mice, which lack functional GABAB receptors, have altered cyclicity, increased GnRH pulsatility and infertility. Moreover, Gnrh1 and Gad1 (enzyme that synthesizes GABA) mRNA expressions are altered in KO hypothalami (H), especially in anterior H (AH) and this is not due to serum estrogen levels. We also showed that Kiss1 mRNA in anteroventral/periventricular (AVPV/PeN) and arcuate (ARC) nuclei is similar to adult WT females (1,2). Here we evaluated the role of brain estrogens in these effects, in WT and KO adult female mice (in estrus) and, comparatively, in males. We also evaluated GnRH pulsatility in the presence of Kiss1r agonist and/or antagonist in E2-treated ovariectomized adult mice. We determined aromatase (Cyp19a1) and alpha estrogen receptor (Er1) mRNA expressions in AH and medial basal H (MBH) and progesterone receptor (Pgr) mRNA expression in micropunches of AVPV/PeN and ARC by qPCR in WT and KO mice.  For in vitro GnRH pulsatility studies, adult WT and KO females were ovariectomized and treated immediately with a single dose of estradiol valerate (sc, 10µg/kg). Seven days post-ovariectomy, they were sacrificed. H were collected and incubated in 250 µl of Krebs-Ringer bicarbonate buffer-4.5 mg/ml glucose-16 mM HEPES at 37°C for 7.5h. Treatments: control (CT), Kiss-10 (agonist, 1.10-7M), Kiss-234 (antagonist, 1.10-7M) and Kiss-10+Kiss-234 (1.10-7M each). Media were collected at 9-min intervals and replaced with fresh medium with/without stimuli. Secreted GnRH was measured by RIA. Cyp19a1 was higher in males vs females (p<0.01) in AH and MBH. Er1 was higher in females vs males (p<0.01) and higher in KO mice vs WTs (p<0.05) in AH and MBH. In AVPV/PeN, Pgr was higher in males vs females (p<0.05), but this difference was lost in KO mice. In ARC, Pgr was lower in KO mice vs WTs (p<0.05), without sex differences. Pulsatility studies revealed that H of WT females have decreased amplitude of GnRH pulses in all treated groups vs CT (p<0.05). However, Kiss-10 induced higher GnRH pulse amplitude in H of KO females compared to WT females (p<0.05). In conclusion, KO H may have a different sensitivity to estrogens due to the higher Er1 expression. Moreover the H of KO females show a different response to Kiss-10 compared to WTs, probably due to different expression levels, desensitization mechanisms and/or signalling of the Kiss1r in these animals.