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Trotta M, Bello EP, Alsina R, Tavella MB, Ferrán JL, Rubinstein M, Bumaschny VF. Hypothalamic Pomc expression restricted to GABAergic neurons suppresses Npy overexpression and restores food intake in obese mice. Mol Metab 2020; 37:100985. [PMID: 32311511 PMCID: PMC7292867 DOI: 10.1016/j.molmet.2020.100985] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/17/2020] [Accepted: 03/23/2020] [Indexed: 12/28/2022] Open
Abstract
Objective Hypothalamic arcuate proopiomelanocortin (Arc-POMC) neurons are involved in different physiological processes such as the regulation of energy balance, glucose homeostasis, and stress-induced analgesia. Since these neurons heterogeneously express different biological markers and project to many hypothalamic and extrahypothalamic areas, it is proposed that Arc-POMC neurons could be classified into different subpopulations having diverse physiological roles. The aim of the present study was to characterize the contribution of the subpopulation of Arc-POMC neurons cosecreting gamma-aminobutyric acid (GABA) neurotransmitter in the control of energy balance. Methods Arc-Pomc expression restricted to GABAergic-POMC neurons was achieved by crossing a reversible Pomc-deficient mouse line (arcPomc−) with a tamoxifen-inducible Gad2-CreER transgenic line. Pomc expression was rescued in the compound arcPomc−/−:Gad2-CreER female and male mice by tamoxifen treatment at postnatal days 25 (P25) or 60 (P60), and body weight, daily food intake, fasting glycemia, and fasting-induced hyperphagia were measured. POMC recovery was quantified by immunohistochemistry and semiquantitative RT-PCR. Neuropeptide Y (NPY) and GABAergic neurons were identified by in situ hybridization. Arc-POMC neurons projecting to the dorsomedial hypothalamic nucleus (DMH) were studied by stereotactic intracerebral injection of fluorescent retrobeads into the DMH. Results Tamoxifen treatment of arcPomc−/−:Gad2-CreER mice at P60 resulted in Pomc expression in ∼23–25% of Arc-POMC neurons and ∼15–23% of Pomc mRNA levels, compared to Gad2-CreER control mice. Pomc rescue in GABAergic-POMC neurons at P60 normalized food intake, glycemia, and fasting-induced hyperphagia, while significantly reducing body weight. Energy balance was also improved in arcPomc−/−:Gad2-CreER mice treated with tamoxifen at P25. Distribution analysis of rescued POMC immunoreactive fibers revealed that the DMH is a major target site of GABAergic-POMC neurons. Further, the expression of the orexigenic neuropeptide Y (NPY) in the DMH was increased in arcPomc−/− obese mice but was completely restored after Pomc rescue in arcPomc−/−:Gad2-CreER mice. Finally, we found that ∼75% of Arc-POMC neurons projecting to the DMH are GABAergic. Conclusions In the present study, we show that the expression of Pomc in the subpopulation of Arc-GABAergic-POMC neurons is sufficient to maintain normal food intake. In addition, we found that DMH-NPY expression is negatively correlated with Pomc expression in GABAergic-POMC neurons, suggesting that food intake may be regulated by an Arc-GABAergic-POMC → DMH-NPY pathway. The subpopulation of arcuate GABAergic-POMC neurons is sufficient to maintain normal food intake. Overweight induced by Pomc deficiency is reduced by arcuate Pomc expression restricted to GABAergic-POMC neurons. DMH-Npy overexpression in POMC-deficient mice is restored by Pomc rescue restricted to GABAergic-POMC neurons. Arcuate POMC neurons projecting to the DMH are mainly GABAergic.
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Affiliation(s)
- Milagros Trotta
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Estefanía Pilar Bello
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Ramiro Alsina
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
| | - María Belén Tavella
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428, Ciudad Autónoma de Buenos Aires, Argentina.
| | - José Luis Ferrán
- Department of Human Anatomy, School of Medicine, University of Murcia and IMIB-Arrixaca Institute, Carretera Buenavista s/n, 30120, El Palmar, Murcia, Spain.
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, 1428, Ciudad Autónoma de Buenos Aires, Argentina; Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, C1428EGA, Ciudad Autónoma de Buenos Aires, Argentina.
| | - Viviana Florencia Bumaschny
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO HOUSSAY), Facultad de Medicina, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina; Departamento de Ciencias Fisiológicas, Facultad de Medicina. Universidad de Buenos Aires, Paraguay 2155, C1121ABG, Ciudad Autónoma de Buenos Aires, Argentina.
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Bello EP, Casas-Cordero R, Galiñanes GL, Casey E, Belluscio MA, Rodríguez V, Noaín D, Murer MG, Rubinstein M. Inducible ablation of dopamine D2 receptors in adult mice impairs locomotion, motor skill learning and leads to severe parkinsonism. Mol Psychiatry 2017; 22:595-604. [PMID: 27431292 DOI: 10.1038/mp.2016.105] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 04/20/2016] [Accepted: 05/06/2016] [Indexed: 11/09/2022]
Abstract
Motor execution and planning are tightly regulated by dopamine D1 and D2 receptors present in basal ganglia circuits. Although stimulation of D1 receptors is known to enhance motor function, the global effect of D2 receptor (D2R) stimulation or blockade remains highly controversial, with studies showing increasing, decreasing or no changes in motor activity. Moreover, pharmacological and genetic attempts to block or eliminate D2R have led to controversial results that questioned the importance of D2R in motor function. In this study, we generated an inducible Drd2 null-allele mouse strain that circumvented developmental compensations found in constitutive Drd2-/- mice and allowed us to directly evaluate the participation of D2R in spontaneous locomotor activity and motor learning. We have found that loss of D2R during adulthood causes severe motor impairments, including hypolocomotion, deficits in motor coordination, impaired learning of new motor routines and spontaneous catatonia. Moreover, severe motor impairment, resting tremor and abnormal gait and posture, phenotypes reminiscent of Parkinson's disease, were evident when the mutation was induced in aged mice. Altogether, the conditional Drd2 knockout model studied here revealed the overall fundamental contribution of D2R in motor functions and explains some of the side effects elicited by D2R blockers when used in neurological and psychiatric conditions, including schizophrenia, bipolar disorder, Tourette's syndrome, dementia, alcohol-induced delusions and obsessive-compulsive disorder.
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Affiliation(s)
- E P Bello
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - R Casas-Cordero
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - G L Galiñanes
- Instituto de Fisiología y Biofísica Bernardo Houssay, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - E Casey
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M A Belluscio
- Instituto de Fisiología y Biofísica Bernardo Houssay, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - V Rodríguez
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - D Noaín
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M G Murer
- Instituto de Fisiología y Biofísica Bernardo Houssay, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.,Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.,Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
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