Tryptophan, 5-HTP, 5-HT and 5-HIAA in the cerebrospinal fluid and sexual behavior in male rats.
No changes were found in the concentration of tryptophan (Trp), 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT) or 5-hydroxyindole acetic acid (5-HIAA) in the cerebrospinal fluid (CSF) of male rats either before sexual activity, immediately after ejaculation of after the postejaculatory refractory period (PEI). Injection of the Trp hydroxylase inhibitor p-chlorophenylalanine (PCPA, 25 or 100 mg/kg i.p. for 3 days) in combination with an injection of the monoamine oxidase inhibitor pargyline (100 mg/kg i.p.) increased the concentration of Trp while decreasing the concentration of 5-HTP, 5-HT and 5-HIAA in the CSF. Furthermore 100 (but not 25) mg/kg PCPA in combination with pargyline caused a significant reduction in the latency to ejaculation. Injection of probenecid (200 mg/kg i.p.), an inhibitor of the transport of 5-HIAA from the CSF, increased the concentration of 5-HIAA in the CSF and slightly prolonged the latency to ejaculation. Sexual activity caused no further increase in CSF 5-HIAA levels in the probenecid-treated rats. Since drug-induced changes in sexual behavior are associated with marked alterations in 5-HT metabolism in the CSF, whereas the changes in the behavior which occur normally are not, these results question the physiological significance of the proposed inhibitory role of 5-HT in male rat sexual behavior.
Qureshi
G A
GA
Department of Renal Medicine, Karolinska Institute, Huddinge, Sweden.
Forsberg
G
G
Bednar
I
I
Södersten
P
P
D006916:5-Hydroxytryptophan / Q000134:cerebrospinal fluid* / Q000378:metabolism / Q000502:physiology; D000818:Animals; D010134:Fenclonine / Q000494:pharmacology; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid* / Q000378:metabolism; D008297:Male; D010293:Pargyline / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000134:cerebrospinal fluid* / Q000378:metabolism / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D014364:Tryptophan / Q000134:cerebrospinal fluid* / Q000378:metabolism / Q000502:physiology
D012701:Serotonin; D014364:Tryptophan; D010293:Pargyline; D006916:5-Hydroxytryptophan; D011339:Probenecid; D010134:Fenclonine; D006719:Homovanillic Acid