@entity75 caused by an acute injury depends on the initial severity of the injury and the time elapsed after the injury. To determine whether these two variables activate common mechanisms, we compared the response of the @entity35 medial septum to insult with a graded series of concentrations of @entity140 ( @entity140 ) with the time-course effects of a low dose of @entity140 . For this purpose we conducted a dose-response study at concentrations of @entity140 between 0.27 and 10.8 nmol to measure @entity194 of the septal area, losses of cholinergic and GABAergic neurons, astroglial and microglial reactions, and @entity730 . Cholinergic neurons, whose loss paralleled the degree of septal @entity194 produced by @entity140 , are more sensitive than GABAergic neurons to the injury produced by @entity140 . At doses of @entity140 above 2.7 nmol, @entity730 and the degree of microglial reaction increased only in the GABAergic region of the septal area, whereas @entity194 and @entity528 reached a plateau. We chose the 2.7-nmol dose of @entity140 to determine how these parameters were modified between 4 days and 6 months after injection. We found that @entity194 and @entity528 increased progressively through the 6-month study period, whereas astrogliosis ceased to be observed after 1 month, and @entity460 precipitates were never detected. We conclude that septal damage does not increase with the intensity of an excitotoxic insult. Rather, it progresses continuously after the insult. Because these two situations involve different mechanisms, short-term paradigms are inappropriate for interpreting the pathogenic mechanisms responsible for long-term neurodegenerative processes.

Pattern of injury with a graded excitotoxic insult and ensuing chronic medial septal damage in the XXXX brain.

@entity75 :: ('MESH:D001927', 'Disease') :: ['Brain damage'] @entity730 :: ('MESH:D002114', 'Disease') :: ['calcification'] @entity194 :: ('MESH:D001284', 'Disease') :: ['atrophy'] @entity140 :: ('MESH:D018350', 'Chemical') :: ['alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid', 'AMPA'] @entity460 :: ('MESH:D002118', 'Chemical') :: ['calcium'] @entity35 :: ('10116', 'Species') :: ['rat'] @entity528 :: ('MESH:D009410', 'Disease') :: ['neuronal loss']
@entity35 :: (10116,Species) :: ['rat']
