PMID- 16423814
OWN - NLM
STAT- MEDLINE
DCOM- 20060209
LR  - 20131121
IS  - 0022-0795 (Print)
IS  - 0022-0795 (Linking)
VI  - 187
IP  - 3
DP  - 2005 Dec
TI  - Endocrine roles of D-aspartic acid in the testis of lizard Podarcis s. sicula.
PG  - 347-59
AB  - In the lizard Podarcis s. sicula, a substantial amount of D-aspartate (D-Asp) is 
      endogenous to the testis and shows cyclic changes of activity connected with sex 
      hormone profiles during the annual reproductive phases. Testicular D-Asp content 
      shows a direct correlation with testosterone titres and a reverse correlation 
      with 17beta-estradiol titres. In vivo experiments, consisting of i.p. injections 
      of 2.0 micromol/g body weight of D-Asp or other amino acids, in lizards collected 
      during the three main phases of the reproductive cycle (pre-reproductive, 
      reproductive and post-reproductive period), revealed that the testis can 
      specifically take up and accumulate D-Asp alone. Moreover, this amino acid 
      influences the synthesis of testosterone and 17beta-estradiol in all phases of 
      the cycle. This phenomenon is particularly evident during the pre- and 
      post-reproductive period, when endogenous testosterone levels observed in both 
      testis and plasma were the lowest and 17beta-estradiol concentrations were the 
      highest. D-Asp rapidly induces a fall in 17beta-estradiol and a rise in 
      testosterone at 3 h post-injection in the testis and at 6 h post-injection in the 
      blood. In vitro experiments show that testicular tissue converted L-Asp into 
      D-Asp through an aspartate racemase. D-Asp synthesis was measured in all phases 
      of the cycle, but was significantly higher during the reproductive period with a 
      peak at pH 6.0. The exogenous D-Asp also induces a significant increase in the 
      mitotic activity of the testis at 3 h (P < 0.05) and at 6 h (P < 0.01). Induction 
      of spermatogenesis by D-Asp is recognized by an intense immunoreactivity of the 
      germinal epithelium (spermatogonia and spermatids) for proliferation cell nuclear 
      antigen (PCNA). The effects of D-Asp on the testis appear to be specific since 
      they were not seen in lizards injected with other D- or L-forms of amino acids 
      with known excitatory effects on neurosecretion. Our results suggest a regulatory 
      role for D-Asp in the steroido-genesis and spermatogenesis of the testis of the 
      lizard Podarcis s. sicula.
FAU - Raucci, F
AU  - Raucci F
AD  - Department of Life Sciences, Second University of Naples, Via Vivaldi 43, 81100 
      Caserta, Italy.
FAU - D'Aniello, S
AU  - D'Aniello S
FAU - Di Fiore, M M
AU  - Di Fiore MM
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Endocrinol
JT  - The Journal of endocrinology
JID - 0375363
RN  - 0 (Proliferating Cell Nuclear Antigen)
RN  - 3XMK78S47O (Testosterone)
RN  - 4SR0Q8YD1X (D-Aspartic Acid)
RN  - 4TI98Z838E (Estradiol)
RN  - EC 5.1.1.- (Amino Acid Isomerases)
RN  - EC 5.1.1.13 (aspartate racemase)
SB  - IM
MH  - Amino Acid Isomerases/metabolism
MH  - Animals
MH  - D-Aspartic Acid/biosynthesis/*physiology
MH  - Estradiol/analysis/blood
MH  - Immunohistochemistry/methods
MH  - Lizards/anatomy & histology/immunology/*physiology
MH  - Male
MH  - Proliferating Cell Nuclear Antigen/analysis
MH  - Reproduction
MH  - Spermatids/immunology
MH  - Spermatogenesis/physiology
MH  - Spermatogonia/immunology
MH  - Testis/anatomy & histology/immunology/*physiology
MH  - Testosterone/analysis/blood
EDAT- 2006/01/21 09:00
MHDA- 2006/02/10 09:00
CRDT- 2006/01/21 09:00
PHST- 2006/01/21 09:00 [pubmed]
PHST- 2006/02/10 09:00 [medline]
PHST- 2006/01/21 09:00 [entrez]
AID - 187/3/347 [pii]
AID - 10.1677/joe.1.06115 [doi]
PST - ppublish
SO  - J Endocrinol. 2005 Dec;187(3):347-59. doi: 10.1677/joe.1.06115.