The injected volumes of 5-HT and
DA were 0.10 ml. All prawns tolerated the injected doses of neurotransmitters
without showing any abnormal behavior. All injections
were performed at 4-day intervals, covering a period of 49
days. The effects of the neurotransmitter-treated groups were
compared with two control groups of 28 animals each. In the first
control group, the animals were untreated and served as a negative
control (NC). The second control group was a vehicle-injected control
(VIC) in which each animal was injected with 0.1 ml of CPS.
Animals in each group were identified by tying plastic loops of different
colors around the eyestalk. The injections were performed
by intramuscular route at the lateral aspect of the second abdominal
segment by using a 1 ml syringe (NIPRO) fitted with 26G 12
”
(0.45 12 mm) thin-wall needles (NIPRO). The weight and total
length of the prawns were measured on every treatment day, before
injection. The total length was evaluated from the base of eyestalk
to the telson (Eyestalk base-telson length, EBTL).
The hemolymph of treated and control prawns was collected
from the substernal hemolymph sinus at 4-day intervals. Each