title: The effect of chronic undernourishment on the synaptic depression of cutaneous pathways in the rat spinal cord.
abstract: The aim of this study was to determine the effect of chronic undernourishment on the amplitude depression of the first negative component in the cord dorsum potentials (N(1)-CDPs) caused by the conditioning stimulation of sensory cutaneous nerves in the rat spinal cord. Single electrical pulses (1Hz; 2 times threshold) applied to the sural (SU) nerve of control rats (n=14) produced CDPs with a first negative component (N(1)-CDPs) larger in amplitude (14.2±1.3%, p<0.01) than those recorded in chronically undernourished rats (n=14; 3 times threshold). The conditioning stimulation of the SP nerve (4 shocks at 300Hz, 3×T) in the control rats (n=5) evoked a long-lasting (~200ms) depression of the N(1)-CDP (60.2±7.2%). In contrast such depression was smaller in magnitude (42.5±5.7%, p<0.01) and time course (100-120ms) in undernourished rats (n=7). The systemic application of picrotoxin (PTX) reduced, but did not abolish the conditioned depression of the N(1)-CDPs and DRPs in both the control and undernourished rats. By assuming that the depression of the N(1)-CDPs is representative of presynaptic mechanisms, it is proposed that chronic undernourishment influence the activation of presynaptic neuronal pathways that regulate the transmitter release of cutaneous afferent fibers in the spinal cord and such effect could act as a compensatory mechanism that counterbalances the decreased activation of spinal neurons by the reduced afferent input in the rat.
authors: Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, AP. 14-740 México, D.F., CP 07000, Mexico. quiroz@fisio.cinvestav.mx
authors: Salvador
authors: S
authors: Quiroz-González
authors: Bertha
authors: B
authors: Segura-Alegría
authors: José Carlos Guadarrama
authors: JC
authors: Olmos
authors: Ismael
authors: I
authors: Jiménez-Estrada
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D044342:Malnutrition / Q000503:physiopathology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012867:Skin / Q000294:innervation*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013497:Sural Nerve / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D018756:GABA Antagonists; D010852:Picrotoxin