The VIP/VPACR system in the reproductive cycle of male lizard Podarcis sicula.
Starting from the knowledge that in the reproductive period the Vasoactive Intestinal Peptide (VIP) is widely distributed in Podarcis sicula testis, we studied VIP expression and the localization of the neuropeptide and its receptors in the testis of the Italian wall lizard P. sicula in the other phases of its reproductive cycle (summer stasis, autumnal resumption, winter stasis, spring resumption). By Real Time-PCR, we demonstrated that testicular VIP mRNA levels change during the reproductive cycle, showing a cyclic trend with two peaks, one in the mid-autumnal resumption and the other in the reproductive period. By in situ hybridization and immunohistochemistry, we demonstrated that both VIP mRNA and protein were widely distributed in the testis in almost all the phases of the cycle, except in the early autumnal resumption. As regards the receptors, the VPAC1R was localized mainly in Leydig cells, while the VPAC2R showed the same distribution of VIP. Our results demonstrate that, differently from mammals, where VIP is present only in nerve fibres innerving the testis, an endotesticular synthesis takes place in the lizard and the VIP synthesis changes throughout the reproductive cycle. Moreover, the VIP/VPAC receptor system distribution observed in germ and somatic cells in various phases of the cycle, and particularly in the autumnal resumption and the reproductive period, strongly suggests its involvement in both spermatogenesis and steroidogenesis. Finally, the wider distribution of VIP in lizards with respect to mammals leads us to hypothesize that during the evolution the synthesis sites have been transferred from the testis to other districts, such as the brain.
Department of Biology, University of Naples Federico II, Naples, Italy.
Marisa
M
Agnese
Department of Biology, University of Naples Federico II, Naples, Italy.
Luigi
L
Rosati
Department of Biology, University of Naples Federico II, Naples, Italy.
Marina
M
Prisco
Department of Biology, University of Naples Federico II, Naples, Italy.
Francesca
F
Coraggio
Department of Biology, University of Naples Federico II, Naples, Italy.
Salvatore
S
Valiante
Department of Biology, University of Naples Federico II, Naples, Italy.
Rosaria
R
Scudiero
Department of Biology, University of Naples Federico II, Naples, Italy.
Vincenza
V
Laforgia
Department of Biology, University of Naples Federico II, Naples, Italy. Electronic address: piero.andreuccetti@unina.it.
Piero
P
Andreuccetti
D000818:Animals; D006801:Humans; D008116:Lizards / Q000235:genetics / Q000502:physiology*; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D018005:Receptors, Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism*; D012098:Reproduction / Q000235:genetics; D012621:Seasons; D013737:Testis / Q000166:cytology / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism*
D012333:RNA, Messenger; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide
Podarcis sicula; Reproductive cycle; Spermatogenesis; VIP; VPAC(1)R; VPAC(2)R