Affiliations: Unidad de Investigación Médica en Farmacología, UMAE Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, México, D. F. Mexico | Laboratorio de Psicobiología, División de Neurociencias, Centro de Investigación Biomédica de Occidente, IMSS; and CUCBA, Universidad de Guadalajara, Guadalajara, Jalisco. Mexico | Facultad de Ciencias Médicas y Biológicas “Dr. Ignacio Chávez”, Universidad Michoacana de SNH, Morelia, Michoacán, Mexico
Note: [] Corresponding author: Gabriela Moralí, Ph.D, Unidad de Investigación Médica en Farmacología, UMAE Hospital de Especialidades, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México, D.F., Mexico. Tel.: (+52) 555 687 8606; E-mail: [email protected]
Abstract: Purpose: To analyze the cytoarchitectural characteristics of the remaining pyramidal neurons in the hippocampal CA1 subfield of rats, four months after global cerebral ischemia (GCI) and progesterone treatment. Methods: Dendritic arborization, and density and shape of the dendritic spines of CA1 pyramidal neurons in brains of intact rats, or rats submitted 120 days earlier to GCI and treatment with progesterone (8 mg/kg) or its vehicle, at 15 min, and 2, 6, 24, 48, and 72 h after the onset of reperfusion, were analyzed in samples processed by a modified Golgi method. Results: Few impregnated CA1 pyramidal neurons were identified in the ischemic vehicle-treated rats, with a short apical dendrite devoid of bifurcations and dendritic spines. In contrast, the remaining CA1 pyramidal neurons sampled from ischemic progesterone-treated rats showed sinuously branched dendrites with similar number of bifurcations and whole density of spines, and higher proportional density of mushroom spines than those in the intact group. Conclusions: These cytoarchitectural characteristics may underlie the long-term preservation of place learning and memory functions seen after ischemia and progesterone neuroprotective treatment, possibly compensating for the severe reduction in neuronal population.
Keywords: Progesterone neuroprotection, global cerebral ischemia, hippocampal pyramidal neurons cytoarchitecture, dendritic spines, rat
