Alterations in metabolism and diurnal rhythms following bilateral surgical removal of the superior cervical ganglia in rats

• Autores: Mul Fedele, Malena L.; Galiana, María D.; Golombek, Diego A.; Muñoz, Estela M.; Plano, Santiago Andrés
• Año de publicación: 2018
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Frontiers in Endocrinology. 2018, 8.
• Materia: MELATONINA; RITMO CIRCADIANO; METABOLISMO; HOMEOSTASIS; FISIOLOGIA; ENDOCRINOLOGIA
• Institución: Pontificia Universidad Católica Argentina

Fil: Mul Fedele, Malena L. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina
Fil: Galiana, María D. Universidad Nacional de Cuyo. Instituto de Histología y Embiología de Mendoza; Argentina
Fil: Golombek, Diego A. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina
Fil: Muñoz, Estela M. Universidad Nacional de Cuyo. Instituto de Histología y Embiología de Mendoza; Argentina
Fil: Plano Santiago A. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina
Fil: Plano Santiago A. Universidad Católica Argentina. Facultad de Ciencas Médicas. Instituto de Investigaciones Biomédicas. Laboratorio de Cronofisiología; Argentina
Abstract: Mammalian circadian rhythms are controlled by a master pacemaker located in the suprachiasmatic nuclei (SCN), which is synchronized to the environment by photic and nonphotic stimuli. One of the main functions of the SCN is to regulate peripheral oscillators to set temporal variations in the homeostatic control of physiology and metabolism. In this sense, the SCN coordinate the activity/rest and feeding/fasting rhythms setting the timing of food intake, energy expenditure, thermogenesis, and active and basal metabolism. One of the major time cues to the periphery is the nocturnal melatonin, which is synthesized and secreted by the pineal gland. Under SCN control, arylalkylamine N-acetyltransferase (AA-NAT)—the main enzyme regulating melatonin synthesis in vertebrates—is activated at night by sympathetic innervation that includes the superior cervical ganglia (SCG). Bilateral surgical removal of the superior cervical ganglia (SCGx) is considered a reliable procedure to completely prevent the nocturnal AA-NAT activation, irreversibly suppressing melatonin rhythmicity. In the present work, we studied the effects of SCGx on rat metabolic parameters and diurnal rhythms of feeding and locomotor activity. We found a significant difference between SCGx and sham-operated rats in metabolic variables such as an increased body weight/food intake ratio, increased adipose tissue, and decreased glycemia with a normal glucose tolerance. An analysis of locomotor activity and feeding rhythms showed an increased daytime (lights on) activity (including food consumption) in the SCGx group. These alterations suggest that superior cervical ganglia-related feedback mechanisms play a role in SCN-periphery phase coordination and that SCGx is a valid model without brain-invasive surgery to explore how sympathetic innervation affects daily (24 h) patterns of activity, food consumption and, ultimately, its role in metabolism homeostasis.