Effect of prenatal forced-swim stress and morphine co-administration on pentylentetrazol-induced epileptic behaviors in infant and prepubertal rats

Prenatal exposure to stress and morphine has complicated effects
on epileptic seizure. Many reports have shown an interaction between morphineand
stress-induced behavioral changes in adult rats. In the present study, effect
of prenatal forced-swim stress and morphine co-administration on pentylentetrazole
(PTZ)-induced epileptic behaviors was investigated in rat offspring to
address effect of the interaction between morphine and stress. Pregnant rats
were divided to four groups of control-saline, control-morphine, stressed-saline
and stressed-morphine. In the stressed group, the rats were placed in 25°C water
on 17–19 days of pregnancy. In the morphine/saline group, the rats received
morphine/saline on the same days. In the morphine/saline-stressed group, they
were exposed to stress and received morphine/saline simultaneously. On
postnatal day 15 (P15), blood samples were collected to determine corticosterone
(COS) level. On P15 and P25, PTZ was injected to the rest of pups to
induce seizure. Then, epileptic behaviors of each rat were individually observed.
Latency of tonic–colonic seizures decreased in control-morphine and stressedsaline
groups while increasing in stressed-morphine rats compared to controlsaline
group on P15. Duration of tonic–colonic seizures significantly increased in
control-morphine and stressed-saline rats compared to stressed-morphine and
control-saline rats on P15, but not P25. COS levels increased in stressed-saline
group but decreased in control-morphine group compared to control-saline rats.
Body weight was significantly higher in morphine groups than saline treated
rats. Prenatal exposure to forced-swim stress potentiated PTZ-induced seizure in
the offspring rats. Co-administration of morphine attenuated effect of stress on
body weight, COS levels, and epileptic behaviors