Spermine and philanthotoxin potentiate excitatory amino acid responses of Xenopus oocytes injected with rat and chick brain RNA

• Published in: Neuroscience letters Vol. 114; no. 1; p. 51
• Main Authors: Brackley, P, Goodnow, Jr, R, Nakanishi, K, Sudan, H L, Usherwood, P N
• Format: Journal Article
• Language: English
• Published: Ireland 22.06.1990
• Subjects: Amino Acids - pharmacology; Animals; Aspartic Acid - analogs & derivatives; Aspartic Acid - pharmacology; Bee Venoms - pharmacology; Brain - physiology; Chickens; Kainic Acid - pharmacology; Male; Membrane Potentials - drug effects; Microinjections; N-Methylaspartate; Neurotoxins - pharmacology; Oocytes - drug effects; Oocytes - physiology; Oxadiazoles - pharmacology; Poly A - administration & dosage; Poly A - genetics; Polyamines; Quisqualic Acid; Rats; Rats, Inbred Strains; RNA - administration & dosage; RNA - genetics; RNA, Messenger; Spermine - physiology; Wasp Venoms - pharmacology; Xenopus
• ISSN: 0304-3940
• DOI: 10.1016/0304-3940(90)90427-B

The effects of spermine and a synthetic analogue (PhTX-343) of the polyamine amide toxin, delta-philanthotoxin, on the responses of Xenopus oocytes to application of amino acids were examined using voltage clamp. The oocytes were injected with either total rat brain RNA or chick cerebrum, poly(A+)RNA. The responses to N-methyl-D-aspartate and L-kainate were potentiated by low concentrations (10(-11)-10(-7) M) of PhTX-343 and by 10(-5)-10(-4) M spermine. There was variability between oocytes in terms of their responsiveness to these compounds and recovery from their effects was slow and often incomplete. Prolonged or repeated applications of PhTX-343 and spermine eventually resulted in inhibition. Higher concentrations of these compounds always inhibited the responses to acidic amino acids. Low concentrations of PhTX-343 and spermine also potentiated the responses to nicotine and gamma-aminobutyric acid. These results are discussed in terms of the postulated polyamine binding site on the N-methyl-D-aspartate receptor.