N,N-dimethylbutylamine

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The route of exposure (i.p.) is not standard. acceptable, well-documented publication which meets basic scientific principles

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1991

Materials and methods

Principles of method if other than guideline:

Exploration if chronic administration of methylamines can cause reproductive toxicity using pregnant CD-1mice and CD-1 mouse embryos in culture as experimental models.

GLP compliance:

not specified

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dimethylamine Hydrochloride

IUPAC Name:

Dimethylamine Hydrochloride

Constituent 2

Reference substance name:

Dimethylammonium chloride

EC Number:

208-046-5

EC Name:

Dimethylammonium chloride

Cas Number:

506-59-2

IUPAC Name:

N-methylmethanaminium chloride

Details on test material:

CAS 506-59-2 (dimethylamine hydrochloride), purity not specified

Test animals

Species:

mouse

Strain:

CD-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, St. Constant, Quebec
- Weight at study initiation: 20-25 g
- Housing: Plexiglas cages with heat-treated wood chip bedding
- Diet (e.g. ad libitum): laboratory mouse chow pellets ad libitum
-Water (e.g. ad libitum): ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22-25°C
- Humidity (%):50-70%
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

other: 0,9 % saline

Details on exposure:

intraperitoneal injections, once a day between 8:00 and 9:00 a.m.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

no data

Details on mating procedure:

mice bought already mated

Duration of treatment / exposure:

day 1-17 of gestation

Frequency of treatment:

daily

Duration of test:

until day 18 of gestation

Doses / concentrations

Remarks:

Doses / Concentrations:
0.25, 1, 2.5 and 5.0 mmol/kg bw ( 11.3, 45.1, 112.7, 225.4 mg/kg bw)
Basis:
nominal conc.

No. of animals per sex per dose:

6-8

Control animals:

yes, concurrent vehicle

Details on study design:

- Six to eight pregnant mice were admininstered 0, 0.25, 1, 2,5 and 5.0 mmol/kg bw dimethylamine by ip injection from day 1 to 17 after mating
- Results of untreated controls of three parallel experiments (n=29) were pooled

Examinations

Maternal examinations:

- Maternal and fetal body weight, mortality, resorptions, litter size, and placental weight were recorded in the in-vivo part of the study

Ovaries and uterine content:

Examination of the uterus for obvious sign of implantations
uteri were stained in 10 % ammonium sulfide solution to identify implantation sites

Fetal examinations:

pubs weight for each female were calculated by dividing the sum of body weights of all live pups in a litter by the number of live pubs in the litter
mean pub weight for each treatment group was based on sum of mean pup weight for each female divided by the number of females in the group
fetuses were randomly placed either in Bouin solution for visceral examination by the freehand razor sectioning technique or in 95 % ethanol for the skeletal examination by an alizarin red S staining technique.

Statistics:

- Statistical evaluation employed Student's t-test and Bonferroni test (multiple means)

Indices:

no data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Details on maternal toxic effects:
- Dimethylamine did not produce maternal toxicity at concentrations up to 2.5 mmol/kg
- Dimethylamine did not affect fetal weights although 3 of 44 dams died, due to reasons not clear.
- Dimethylamine at doses of 5 mmol/kg caused contractions of abdominal muscles in the proximity of injektion sites, these contractions lasted 2-3 min
- For evaluation the results of untreated controls of three parallel experiments (n=29) were pooled
- No dam died from dimethylamine treatment and maternal body weight development within the range of the untreated control group
- At 225.4 mg/kg bw contractions of the muscles at the injection site lasting 2-3 minutes after dosing were observed
- No significant differences between control and treated animals were observed concerning fetal body weight, mortality, resorptions , litter size, or placental weight

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

> 225.4 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

> 112.7 mg/kg bw/day

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes. Remark: at the highest concentration higher number of resorbed and dead fetuses

Details on embryotoxic / teratogenic effects:
- Dimethylamine did not have any significant effect on pregnancy outcome.
- DMA did not adversely affect fetal development in vivo.
- Number of resorbed and dead fetuses were equally distributed across all doses of DMA, but the highest dose (5 mmol/kg bw) caused a not significant increased number of dead fetuses and a signifcant higher number of resorptions.
- none of the amines (MMA, DMA, TMA) caused a significant increase in external, interna organ, or skeletal abnormalities.
- all three methylamines possess teratogenic potential in varying degrees.
- decrease of DNA, RNA, and protein after treatment of embryos with methylamines.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

In vitro studies: all three methylamines produced concentration-dependent decreases in yolk-sac diameter, crown-rump length, head length, and fetal survival; developmental score and somite number also exhibited a similar concentration-dependent decrease.

The effect of all the three methylamines was more marked on the head length than on crown-rump length and yolk-sac diameter.

The development of yolk-sac circulation was severly affected at 0.25 mM DMA and TMA. The color of the yolk sac of DMA- and TMA-treated embryos was paler than control and there appeared to be a decrease in flow rather than vascularization.

The external appearance of embryos was not affected by low concentrations of methylamines. at higher concentrations (> 0.5 mM), there appeared to be a dispropotionate retardation in forelimb and branchial bar development relative to the development of other organs. All embryos were dorsally convex at 1 mM MMA or DMA.

The development of hearts was unaffected at concentrations up to 1 mM of all 3 methylamines and neuropores closed well up to concentrations of 0.75 mM.

All three methylamines produced concentration-dependent decreases in embryo RNA, DNA and proteins; the relative order of toxicity was the same as in vivo, namely TMA> DMA > MMA.

TABLE 2. Effects of Dimethylamine on Pregnancy Outcome in CD-1 Mice
Variables	Dose (mmol/kg/d, ip, d 1-17 of gestation)
	0	0.25	1.0	2.5	5.0
Animals (n)	29	9	13	11	11
Day 1 body weight (g)	23.9 ± 0.1	22.8 ± 0.4	24.2 ± 0.8	24.7 ± 0.5	25.0 ± 0.5
Day 18 body weight (g)	48.4 ± 1.1	48.9 ± 1.0	50.1 ± 2.2	50.9 ± 1.5	45.9 ± 2.0
Dams dead (n)	0	0	2	0	1
Dead fetuses/litter	0.83 ± 0.14	0.78 ± 0.32	0.63 ± 0.26	0.86 ± 0.4	1.29 ± 0.36
Resorptions/litter	0.66 ± 0.13	0.44 ± 0.34	0.75 ± 0.62	0.57 ± 0.2	1.71 ± 0.68^a
Litter size (n)	9 ± 1	9 ± 1	10 ± 1	10 ± 1	8 ± 1
Fetal body weight (g)	1.4 ± 0.03	1.5 ± 0.05	1.4 ± 0.03	1.4 ± 0.04	1.4 ± 0.03
Placental weight (mg)	109 ± 2	114 ± 4	114 ± 6	116 ± 5	109 ± 5
ARI	1.63 ± 0.4	0.90 ± 0.3	3.1 ± 1.1	0.7 ± 0.2	2.6 ± 1.1
Note.Mice were killed on d 18 of gestation; fetal and placental weights represent mean of weights per litter; ARI (adverse reproductive index) represents cumulative maternal and fetal toxicity in arbitrary units. Data are mean ± SE. ^aSignificantly (p < .05) greater than the corresponding control value.

 

Applicant's summary and conclusion

Conclusions:

- The NOAEL for maternal toxicity was 225.4 mg/kg bw based on the absence of any adverse findings at this dose,
and for developmental toxicity, including teratogenicity, the NOAEL was 112.7 mg/kg bw based on the absence of any adverse findings at this dose,

Executive summary:

DMA inhibits development of mouse embryos in culture.

DMA may act as endogenous teratogens unter certain conditions.