Synaptic functions in the aged rat hippocampus: a target for corticosteroids?
The role of corticosteroids in brain aging remains a controversial issue. Conceivably, if corticosteroids levels are increased in the aged brain, neuronal function might be altered. For instance, GABA-mediated synaptic events, spike accommodation and afterhyperpolarizing potentials (AHPs) might be modified. Our electrophysiological results show that the most consistent alterations observed in the aged rat hippocampus concern cholinergic receptors, glutamatergic NMDA receptors and GABAB receptors mediated synaptic potentials. In contrast no consistent alterations were observed in afterhyperpolarizing potentials, calcium spikes, or GABAA mediated synaptic events. Therefore our electrophysiological results are difficult to reconcile with a 'glucocorticoid cascade hypothesis,' involving an elevated level of corticosterone in the aged rat.
Lamour
Y
Y
INSERM Unité 161, Paris, France.
Potier
B
B
Jouvenceau
A
A
Billard
J M
JM
Dutar
P
P
D000305:Adrenal Cortex Hormones / Q000494:pharmacology*; D000818:Animals; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects / Q000254:growth & development*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018080:Receptors, GABA-B / Q000187:drug effects / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013570:Synaptic Membranes / Q000187:drug effects / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000305:Adrenal Cortex Hormones; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid