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Treatment-related functional observational battery (FOB) findings were recorded at the time
of maximal inhibition of cholinesterase activity (i.e. about 90 min after dosing) at doses of 1 mg/kg
bw or greater on day 0, but not at any dose on day 7 or 14 after treatment. A summary of FOB findings
is presented in Table 14. In addition, males at 6 and 12 mg/kg bw and females at 6 mg/kg bw
had significantly lower (p ≤ 0.05) body temperature (by about 3.4% and 3.9%, and 2.8% for males
and females, respectively) after treatment on day 0, and appeared to be treatment-related. Males and
females at the highest dose had significantly reduced forelimb grip performance (by about 31% and
27%, respectively). Similarly, significant reductions (p ≤ 0.05) in hindlimb grip performance were
noted only in males at 6 and 12 mg/kg bw (reduced by 18% and 30%, respectively). These manifestations
were attributed to acute cholinergic effects of the test substance. Foot splay was unaffected by
treatment.
In males, the response profile of remaining reflex/physiological observations such as touch
(5 out of 12 and 6 out of 12), righting (slightly uncoordinated, 6 out of 12 and 3 out of 12) and righting
(land on side, 2 out of 12 and 5 out of 12) for the groups at 6 and 12 mg/kg bw, respectively, was
significantly different (p ≤ 0.05) from the controls and appeared to be treatment-related, although a
dose–response relationship was not always observed.
Maze activity in treated rats was lower on day 0 (by about 64%, 60%, 77% and 79% for
males at 0, 2, 6 and 12 mg/kg and 71%, 78%, 79% and 85% for females at 0, 1, 3 and 6 mg/kg
bw, respectively) compared with the corresponding values reported before treatment and appeared
to be treatment-related. In comparison to the concurrent controls, dose-related reductions in motor
activity were seen in males at 6 and 12 mg/kg bw (about 36% and 43%, respectively), and
in females (about 19% for the groups at 1 and 3 mg/kg bw and about 44% at 6 mg/kg bw). The
Table 14. Functional observational battery findings after dosing (day 0) in rats given
azinphos-methyl by gavage
Parameter Males Females
Dose (mg/kg bw)
2 6 12 1 3 6
Number of animals tested 12 12 11 12 12 3
Autonomic effects
Lacrimation 0 3 1 0 0 1*
Salivation 0 4 4 0 0 1*
Neuromuscular effects
Incoordination (home cage) 0 1 3 0 0 1*
Incoordination (open field) 0 6* 7* 0 0 1*
Repetitive chewing (home cage) 0 3 7* 0 0 1*
Repetitive chewing (open field) 0 8* 10* 0 0 1*
Posture 0 3* 6* 0 1 1*
Minimal movement 1 3 6 0 0 1
Central nervous system effects
Muscle fasciculations (home cage) 0 8* 12* 0 0 1*
Muscle fasciculations (open field) 0 12* 12* 0 0 1*
Tremors (home cage) 0 3 9* 0 0 1*
Tremors (open field) 0 6* 9* 0 0 1*
From Sheets & Hamilton (1994)
* Significantly different from corresponding controls (p ≤ 0.05).
AZINPHOS-METHYL 139–172 JMPR 2007