Table 1.

Levels of endogenous NAEs in the periimplantation mouse uterus

Day of Pregnancy	No. of determinations	Chain length:number of double bonds, pmol/μmol lipid phosphorus, mean ± SD
		16:0	18:0	18:1n-9	18:1n-7	18:2n-6	20:4n-6 Anandamide*
1	2	10.8 ± 1.2	11.0  ± 0.1	43.6  ± 21.9	1.3  ± 0.9	0.6  ± 0.4	289  ± 17.6
2	2	9.7 ± 0.0	11.5  ± 0.7	13.4  ± 0.1	1.8  ± 0.1	0.4  ± 0.4	428  ± 32.1
3	2	12.2 ± 1.3	13.4  ± 1.1	8.8  ± 2.2	3.2  ± 0.9	0.5  ± 0.3	566  ± 160.2
4	3	10.1 ± 0.7	8.8  ± 1.3	12.0  ± 3.7	1.9  ± 0.4	0.7  ± 0.4	345  ± 66.0
4, pseudopregnant	2	11.6 ± 0.04	9.6  ± 0.7	10.6  ± 4.0	0.9  ± 0.6	0.8  ± 0.6	509  ± 12.2
5, pseudopregnant	3	11.1 ± 1.0	11.6  ± 0.4	15.8  ± 4.3	1.9  ± 0.9	1.0  ± 0.4	937  ± 13.8
5, implant sites	3	15.7 ± 0.03	7.5  ± 10.7	5.8  ± 0.3	1.9  ± 0.2	1.4  ± 0.03	142  ± 1.7
5, interimplant sites	3	8.0 ± 1.1	11.6  ± 1.6	3.5  ± 0.8	2.1  ± 0.4	0.8  ± 0.1	583  ± 5.0
7, implant sites	3	17.1 ± 0.2	38.1  ± 4.2	8.9  ± 1.3	4.1  ± 0.5	1.3  ± 0.5	330  ± 68.5
7, interimplant sites	3	21.2 ± 0.9	18.1  ± 2.3	40.0  ± 12.0	1.4  ± 1.0	1.8  ± 0.9	1,345  ± 140.0

NAEs, isolated by TLC from lipid extracts of whole uteri, implantation sites, or interimplantation sites on indicated days of pseudopregnancy or pregnancy were analyzed by GC-MS. Levels of anandamide in day 5 pseudopregnant uteri were significantly higher (P < 0.05) from those on days 1–4 of pregnancy or pseudopregnancy (ANOVA followed by Student’s t-test). Level of anandamide in interimplantation sites were significantly higher (P < 0.05) than those from implantation sites (paired t-test). 

^*Other polyunsaturated NAEs may also be present but were not included in this assay.