Melatonin and Methoxytryptophol have Temporal Effect on Tail Elongation but not Methoxytryptamine: Studies on Tail Regeneration in Hemidactylus flaviviridis

In order to evaluate the time-specific influence of pineal indoles on tail regeneration in lizards, melatonin (M), methoxytryptophol (ML) and methoxytryptamine (MT) were administered intraperitonealy to different groups of lizards at morning 7:00 hrs (m) or in the evening at 17:00 hrs (e). The Mm and MLe groups of lizards showed a delay in the attainment of various arbitrary stages of regeneration like wound healing, pre-blastema, blastema and initiation of growth while the Me and MLm groups of lizards showed hastened attainment. However, MTm and MTe treatments did not bring about any difference compared to the controls. The total length of tail regenerated and percentage replacement at the end of 30 days were significantly less in Mm and MLe groups of lizards. MTm and MTe treatments, however, did not affect the regeneration process. The results indicate that M and ML have opposite time-specific effects on regeneration, while MT has no effect. Apparently, M and ML are part of the photoperiodic and neuro-endocrine transduction mechanisms related to regenerative growth in lizards.