Functional change in the 5-HT presynaptic receptor in spinal cord of aged rats.
The present study assessed the functional integrity of the serotonin (5-HT) presynaptic receptor in the spinal cord of aged (18-20 months) rats. Previous research determined that exogenous 5-HT and 5-HT1B agonists, in adult (3 months) rats, activated the 5-HT presynaptic receptor resulting in a dose-dependent decrease in 3H-5-HT release from spinal cord slices. Contrastively, exogenous 5-HT and the selective 5-HT1B agonist 1-(m-chlorophenyl) piperazine HCl (mCPP) produced a dose-dependent increase in depolarization-evoked 3H-5-HT release from spinal cord of aged rats. The selective 5-HT1A agonist 8-hydroxy-2(di-n-propylamino) tetralin (8-OHDPAT) increased 3H-5-HT release from aged rat spinal cord slices similar to results previously obtained from adult rat spinal cord slices. The inability of 5-HT and mCPP to inhibit 3H-5-HT release from spinal cord of aged rats indicates a functional change in the 5-HT presynaptic receptor in these animals. Possible mechanisms mediating this functional change are discussed.
Murphy
R M
RM
Department of Psychiatry, University of Cincinnati College of Medicine, OH 45267-0559.
Zemlan
F P
FP
D000375:Aging / Q000502:physiology; D000818:Animals; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D012702:Serotonin Antagonists / Q000494:pharmacology; D013116:Spinal Cord / Q000502:physiology*
D010879:Piperazines; D017981:Receptors, Neurotransmitter; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D012701:Serotonin; C015068:1-(3-chlorophenyl)piperazine