Fetal rat brain ornithine decarboxylase (ODC) activity and polyamine levels following exposures to Iridium cell phone fields in late pregnancy

Adey WR,

Unpublished but presented at a workshop in Washington, D.C. on Feb 4 2000

Department of Biochemistry, University of California, Riverside, CA  92521

From the amino acid ornithine, the enzyme ornithine decarboxylase (ODC) synthesizes highly charged, polycationic long chain polyamines: putrescine, spermidine and spermine.  They are sensitive markers for external stimuli and are indicators for both growth and stress.  They are essential in DNA synthesis.  

Overexpression of ODC in initiated cells leads to tumor formation in the absence of any other promotors.  ODC activity in cultured cells is sensitive to both ELF fields and to microwave fields with ELF modulation.  We have tested effects of repeated, intermittent simulated exposure to IRIDIUM cell phone fields in late pregnancy on brain ODC activity and polyamine levels in Fischer 344 fetal rats.  IRIDIUM signals use a Time Division Multiple Access (TD MA) modulation with 11 packets/sec at a carrier frequency of 1.6 GHz.

We performed an initial experiment and 1 replication (Cain et al. Proc 21st BEMS Annual Meeting, pp 126-127, 1999). Experimental conditions included cage-controls (5 litters, n=21), sham-exposed (5 litters, n=40); uterine exposures at SAR = 0.16 W/kg (3 litters, n=16); at uterine SAR = 1.6 W/kg (5 litters, n=40); and at uterine SAR 5.0 W/kg (4 litters, n=20).  A near-field exposure system utilized 2 stacked acrylic platforms for simultaneously exposing and sham-exposing.  Each had a central, vertically oriented antenna surrounded by 10 radial animal restraint tubes.  Rats were positioned with their hindquarters toward the antenna for maximum uniformity in fetal dosimetry. 

On Gestation Days (GDs) 18-21, timed-pregnant dams were exposed or sham-exposed fo r 2h/day.  On GD21, dams were sacrificed and fetal cerebral and cerebellar ODC activity and polyamine levels of putrescine, spermidine and spermine determined.

Field exposures significantly decreased cerebral and cerebellar ODC activity compared to sham-exposed fetuses.

 
• Cerebral ODC activity in exposed fetuses was in the range 56, 57 and 59% of sham-exposed at uterine SARs of 0.16 (p<0.05), 1.60 (p<0.01) and 5.0 W/kg (p<0.01) respectively. 
• Cerebral polyamine levels were unchanged by field exposure. 
• Cerebellar ODC activity in field-exposed fetuses was 60% (p<0.05), 83% (NS) and 89% (NS) of sham-exposed rats for the same respective range of SARs. 
• Cerebellar putrescine levels in field-exposed fetuses were 150% (NS), 145% (p<0.01) and 83% (NS) of sham-exposed rats at the same respective SAR levels. 
• Cerebellar spermidine levels in field-exposed fetuses were 76% (NS), 68% (p<0.001) and 76% (p<0.05) of sham-exposed rats at the respective SAR levels.
• Cerebellar spermine levels were 79% (NS), 77% (p<0.05) and 75% (p<0.05) of sham-exposed rats at the same respective SAR levels. 
• Tube restraint reduced cerebral and cerebellar IDC activity to 50%.  (p<0.01) and 65% (p<0.05) respectively of levels in cage-controls. 
• Tube restraint reduced cerebral putrescine levels to 77% (p<0.05) of cage-controls. 

Further studies would evaluate
1) autoregulation of ODC activity by exported putrescine;
2) temporal factors governing regional cell density in brain development; and
3) differential regional functional organization in brain tissue maturation.