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Administrative data

Endpoint:
short-term repeated dose toxicity: other route
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: A research paper using very large doses subcutaneously to demonstrate sex-differences in the ventilation-rate. Not relevant for REACH and not reliable because it is insufficiently described.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1986

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Increasing doses of monosodium aspartic acid were dosed sc to neonatal rats from Day 2 to 11. Twelve months later ventilatory and metabolism investigations were performed on theses rats.
GLP compliance:
not specified
Limit test:
yes

Test material

Constituent 1
Reference substance name:
monosodium aspartic acid
IUPAC Name:
monosodium aspartic acid
Details on test material:
Supplier: Sigma.

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
Male and female Sprague-Dawley rats obtained from Sasco (Omaha, NE) were bred in our laboratory, which was kept at 21 °C and a 12h/12h photoperiod.
The animals were housed in steel mesh cages and had free access to Purina mouse/rat chow and tap water.
On day 21 the rats were weaned, separated by sex, and housed in groups of five animals.
Saline- and aspartic acid-treated male and female 12-months-old rats were used in the present study.

Administration / exposure

Route of administration:
subcutaneous
Vehicle:
water
Details on exposure:
Litters obtained at birth were assigned randomly to two groups: saline-injected (control) and aspartic acid­injected pups. Neonatal pups of the latter group were injected subcutaneously daily with a 10% aqueous solution of monosodium aspartic acid (Sigma) from days 2 to 11 with a gradually increasing dose from 2.2 to 4.4 mg/g. The control group received subcutaneous injections of saline of the same volume as the aspartic-injected groups.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
10 days from Day 2 to 11 after birth.
Frequency of treatment:
No data. Presumably daily.
Doses / concentrations
Remarks:
Doses / Concentrations:
Increasing doses from "2.2 to 4.4 mg/g". Presumably this is 2200 to 4400 mg monosodium aspartic acid/kg bw/d.
No. of animals per sex per dose:
10
Control animals:
other: concurrent, "saline", same dose volume.

Examinations

Observations and examinations performed and frequency:
Ventilatory and metabolic measurements were made in a 30-cm-long, 14-cm-diam Plexiglas plethysmograph. Tidal volume, inspiratory and expiratory times, breathing frequency, and minute ventilation were determined using a modification of the technique of Bartlett and Tenney. Instead of a reference chamber, a small leak was created with a 20-gauge needle to maintain the stability of the ventilatory recording.
The rat was weighed, the nose-anus length measured to calculate the Lee index, a measure of obesity.

Results and discussion

Results of examinations

Body weight and weight changes:
effects observed, treatment-related
Details on results:
The body weight of aspartic acid-treated female rats was greater than that of the control females, although body weights of the two male groups did not differ. Aspartic acid treatment resulted in a shorter body as well as obesity in both female and male rats.
Metabolic rates were not different between male or female control and aspartic acid-treated animals.
The treatment has different effects on ventilation and ventilatory responses to hypoxia or hypercapnia in adult animals of each sex.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

The treatment has different effects on ventilation and ventilatory responses to hypoxia or hypercapnia in adult animals of each sex.

Applicant's summary and conclusion

Executive summary:

Ventilation was evaluated in 12-month-old male and female rats that had received large doses of aspartic acid neonatally. Rats of both sexes treated with aspartic acid were obese, stunted, and exhibited hypogonadism. Although metabolic rates of the aspartic acid-treated rats were not different compared with sex-matched controls, ventilatory patterns were different. The treatment has different effects on ventilation and ventilatory responses to hypoxia or hypercapnia in adult animals of each sex.

 

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