Research Areas

  • Cell Biology / Molecular Biology
  • Neurobiology / Neurophysiology

 

The Laboratory of Neurophysiology is dedicated to study various aspects of cellular and molecular biology of sexual differentiation of the brain before (and after) the organizing action of gonadal steroids in utero. The classical hypothesis argues that the sexual dimorphism of non-gonadal tissues such as the brain is a consequence of gonadal steroids action. The organization of male brain circuits is the result of the action of androgens secreted by the testis during the “critical period” of brain development, while the organization of the female brain occurs in the absence of testicular secretions, irrespectively of sex chromosome complement. Although the role of gonadal steroids in sexual dimorphisms is undeniable, our group and other laboratories have demonstrated that some sex differences in the brain and other tissues are a consequence of a multifactorial process in which hormonal, genetic and epigenetic factors could act before or in parallel with gonadal hormones. Current projects in the lab use biochemical, molecular and electrophysiological procedures to evaluate the contribution of these factors using the mouse model known as Four Core Genotype in which the gonadal sex and sex chromosome complement are dissociated.

 Dra. María Julia Cambiasso. Independent  Researcher of CONICET

 

Role of X-linked genes in the generation of sex differences in neuronal development

 Sexual differentiation of the brain results from the complex interplay of diverse hormonally regulated mechanisms, including morphological differentiation of individual neurons and epigenetic activity.  Previous findings from our lab indicate that hypothalamic neurons show sex differences in neuritogenesis, female neurons have longer axons and higher levels of the neuritogenic factor neurogenin 3 (Ngn3) than male neurons in vitro. Moreover, the effect of 17-β-estradiol (E2) on axonal growth and Ngn3 expression is only found in male derived neurons.  We evaluated the role of sex chromosome complement on the regulation of axonal effect of E2 and also on the Ngn3 expression and regulation in hypothalamic neurons before the critical period of sexual differentiation. We found that sex chromosomes regulate early development of hypothalamic neurons by orchestrating not only sex differences in neuritogenesis, but also regulating the effect of E2 on Ngn3 expression through activation of ERα in hypothalamic neurons. We are currently analyzing the sex-biasing contribution of X-linked genes on sex differences in neuronal development and neuritogenesis.

 

Role of the sex chromosome complement as a primary orchestrator of epigenetic mechanisms involved in brain sexual differentiation

Both hormonal and genetic factors interact to induce long lasting effects on sexually dimorphic gene expression. Epigenetic mechanisms such as DNA mehtylaiton and histone acetylation have been proposed as mediators of hormonal-dependent sexual differentiation of the brain. Interestingly, some of the X- and Y-linked genes are epigenetic regulators involved in brain development. We testing the hypothesis that  X/Y chromosomes are the primary regulators of the epigenetic machinery involved in the sexual differentiation of brain. To this end we use mice of the four core genotype model to dissect the contribution of sex chromosomes and gonadal hormones in the regulation of DNA methylation and histone acetylation during development.

 

Sex differences in GABA response in hypothalamic neurons in vitro

GABAA receptor functions are dependent on subunit composition and, through their activation, GABA can exert trophic actions in immature neurons. Several sex differences in GABA-mediated responses are gonadal hormone-dependent; however, few studies have dealt with sex differences detected before the critical period of brain masculinization. In this project, we are evaluating early sex differences in GABAA receptor functionality before the critical period of sexual differentiation.  Performing calcium imaging and electrophysiology recordings we demonstrated that calcium entry in immature hypothalamic neurons is mainly through L-type voltage-dependent calcium channels. Nifedipine blocked calcium entry more efficiently in male than in female neurons. There were more male than female neurons responding to GABA, and they needed more time to return to resting levels. Pharmacological characterization revealed that propofol enhanced GABAA-mediated currents and blunted GABA-mediated calcium entry more efficiently in female neurons than in males. Testosterone treatment did not erase such sex differences. These data suggest sex differences in the expression of GABAA receptor subtypes. GABA-mediated responses are sexually dimorphic even in the absence of gonadal hormone influence, suggesting genetically biased differences. These results highlight the importance of GABAA receptors in hypothalamic neurons even before hormonal masculinization of the brain.

 

Effect of estradiol on the inflammatory response of dental pulp fibroblasts

We are also investigating the mechanism of E2-action on dental pulp fibroblast in an inflammation model of LPS exposure. We have characterized the pulp fibroblast cultures and found that the cells express ERβ and PGER (but no ERα), TLR4 and respond to LPS through   IL-6 and TNFα in a time dependent manner. VEGF did not change over time. We are currently analyzing the signaling cascade activated by E2 in response to LPS stimulation.

 

Associate Researchers

 

Dr. Carla Cisternas

Ccisternas@immf.uncor.edu

 

 

Students

 

Biol. Lucas Cabrera Zapata

lcabrerazapata@immf.uncor.edu

 

 

Od. Sabrina Soto

ssoto@immf.uncor.edu

 

 

Lic. Camila Sosa

csosa@immf.uncor.edu

 

 

GRANTS

  • CONICET, FONCyT, MINCyT CBA, SECyT-UNC, IBRO-LARC and CSIC-Spain.

 

PUBLICATIONS (Last 5 Years)

  1. Cisternas CD, Cabrera Zapata LE, Mir FR, Scerbo MJ, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Estradiol-dependent axogenesis and Ngn3 expression are determined by XY sex chromosome complement in hypothalamic neurons. Sci Rep.2020 May 19;10(1):8223. doi: 10.1038/s41598-020-65183-x. PMID: 32427857.
  2. Mir FR, Wilson C, Cabrera Zapata LE, Aguayo LG, Cambiasso MJ. Gonadal hormone-independent sex differences in GABAA receptor activation in rat embryonic hypothalamic neurons. Br J Pharmacol. 2020 Mar 4. doi: 10.1111/bph.15037. Epub ahead of print. PMID: 32133616.
  3. Cabrera Zapata LE, Bollo M, Cambiasso MJ. Estradiol-Mediated Axogenesis of Hypothalamic Neurons Requires ERK1/2 and Ryanodine Receptors-Dependent Intracellular Ca2+ Rise in Male Rats. Front Cell Neurosci. 2019 Apr 2;13:122. doi: 10.3389/fncel.2019.00122. PMID: 31001087; PMCID: PMC6454002.
  4. Virgolini MJ, Feliziani C, Cambiasso MJ, Lopez PH, Bollo M. Neurite atrophy and apoptosis mediated by PERK signaling after accumulation of GM2-ganglioside. Biochim Biophys Acta Mol Cell Res. 2019 Feb;1866(2):225-239. doi: 10.1016/j.bbamcr.2018.10.014. Epub 2018 Oct 30. PMID: 30389374.
  5. Rulli SB, Cambiasso MJ, Ratner LD. Programming of the reproductive axis by hormonal and genetic manipulation in mice. Reproduction. 2018 Oct 1;156(4):R101–R109. doi: 10.1530/REP-18-0054. PMID: 30304933.
  6. Cambiasso MJ, Cisternas CD, Ruiz-Palmero I, Scerbo MJ, Arevalo MA, Azcoitia I, Garcia-Segura LM. Interaction of sex chromosome complement, gonadal hormones and neuronal steroid synthesis on the sexual differentiation of mammalian neurons. J Neurogenet. 2017 Dec;31(4):300-306. doi: 10.1080/01677063.2017.1390572. Epub 2017 Oct 27. PMID: 29078716.
  7. Cisternas CD, Garcia-Segura LM, Cambiasso MJ. Hormonal and genetic factors interact to control aromatase expression in the developing brain. J Neuroendocrinol. 2018 Feb;30(2). doi: 10.1111/jne.12535. PMID: 28891264.
  8. Cisternas CD, Cabrera Zapata LE, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Regulation of aromatase expression in the anterior amygdala of the developing mouse brain depends on ERβ and sex chromosome complement. Sci Rep. 2017 Jul 13;7(1):5320. doi: 10.1038/s41598-017-05658-6. PMID: 28706210; PMCID: PMC5509695.
  9. Dadam FM, Cisternas CD, Macchione AF, Godino A, Antunes-Rodrigues J, Cambiasso MJ, Vivas LM, Caeiro XE. Sex chromosome complement involvement in angiotensin receptor sexual dimorphism. Mol Cell Endocrinol. 2017 May 15;447:98-105. doi:  10.1016/j.mce.2017.02.041. Epub 2017 Feb 27. PMID: 28254489.
  10. Mir FR, Carrer HF, Cambiasso MJ. Sex differences in depolarizing actions of GABAA receptor activation in rat embryonic hypothalamic neurons. Eur J Neurosci. 2017 Feb;45(4):521-527. doi: 10.1111/ejn.13467. Epub 2016 Nov 25. PMID: 27888546.
  11. Rossetti MF, Cambiasso MJ, Holschbach MA, Cabrera R. Oestrogens and Progestagens: Synthesis and Action in the Brain. J Neuroendocrinol. 2016 Jul;28(7). doi: 10.1111/jne.12402. PMID: 27306650.
  12. Cisternas CD, Tome K, Caeiro XE, Dadam FM, Garcia-Segura LM, Cambiasso MJ. Sex chromosome complement determines sex differences in aromatase expression and regulation in the stria terminalis and anterior amygdala of the developing mouse brain. Mol Cell Endocrinol. 2015 Oct 15;414:99-110. doi: 10.1016/j.mce.2015.07.027. Epub 2015 Jul 29. PMID: 26231585.
  13. Scerbo MJ, Freire-Regatillo A, Cisternas CD, Brunotto M, Arevalo MA, Garcia-Segura LM, Cambiasso MJ. Neurogenin 3 mediates sex chromosome effects on the generation of sex differences in hypothalamic neuronal development. Front Cell Neurosci. 2014 Jul 8;8:188. doi: 10.3389/fncel.2014.00188. PMID: 25071448; PMCID: PMC4086225.
  14. Gonzalez B, Ratner LD, Scerbo MJ, Di Giorgio NP, Poutanen M, Huhtaniemi IT, Calandra RS, Lux-Lantos VA, Cambiasso MJ, Rulli SB. Elevated hypothalamic aromatization at the onset of precocious puberty in transgenic female mice hypersecreting human chorionic gonadotropin: effect of androgens. Mol Cell Endocrinol. 2014 Jun 5;390(1-2):102-11. doi: 10.1016/j.mce.2014.04.005. Epub 2014 Apr 19. PMID: 24755422.
  15. Vivas L, Godino A, Dalmasso C, Caeiro XE, Macchione AF, Cambiasso MJ. Neurochemical Circuits Subserving Fluid Balance and Baroreflex: A Role for Serotonin, Oxytocin, and Gonadal Steroids. In: De Luca LA Jr, Menani JV, Johnson AK, editors. Neurobiology of Body Fluid Homeostasis: Transduction and Integration. Boca Raton (FL): CRC Press/Taylor & Francis; 2014. Chapter 9. PMID: 24829993.
  16. Dadam FM, Caeiro XE, Cisternas CD, Macchione AF, Cambiasso MJ, Vivas L. Effect of sex chromosome complement on sodium appetite and Fos-immunoreactivity induced by sodium depletion. Am J Physiol Regul Integr Comp Physiol. 2014 Feb 1;306(3):R175-84. doi: 10.1152/ajpregu.00447.2013. Epub 2013 Nov 20. PMID: 24259464.