Neurotoxicology and Teratology, Vol. 13, pp. 271-273. ©Pergamon Press plc, 1991. Printed in the U.S.A.
0892-0362/91 $3.00 + .00
Prenatal Nicotine Exposure Increased Susceptibility to Electroconvulsive Shock (ECS) in Adult Rats S E R G I O A. B R I T O S A N D O T T O A. O R S I N G H E R
Departamento de Farmacologfa, Facultad de Ciencias Quimicas, Universidad Nacional de Crrdoba Sucursal 16, C. C. 61, 5016, Cdrdoba, Argentina R e c e i v e d 1 O c t o b e r 1990
BRITOS, S. A. AND O. A. ORSINGHER. Prenatal nicotine exposure increased susceptibility to electroconvulsive shock (ECS) in adult rats. NEUROTOXICOL TERATOL 13(3) 271-273, 1991.--Female rats were treated during pregnancy (days 1-20) with nicotine (1 mg/kg SC, b.i.d.). When some aspects of maternal behavior and developmental parameters were recorded in mothers and pups, respectively, no changes were detected in the experimental group as compared with controls. However, adult offspring of nicotine-treated rats showed an increased susceptibility to ECS. These results demonstrate long-lasting deleterious effects induced by nicotine exposure during fetal life. Prenatal nicotine exposure
Electroconvulsive shock
DIFFERENT lines of evidence, arising from experimental and clinical fields, have pointed to deleterious effects induced by prenatal nicotine exposure. Maternal smoking represents a high risk factor for sudden infant death syndrome (8,11), and it is also involved in the pathogeny of other functional disorders, such as Minimal Brain Disfunction, locomotive and growth retardation as well as learning impairment (11). Different experimental models have been used in order to assess the deleterious effects induced by perinatal nicotine administration. Offspring of rats treated with nicotine during pregnancy revealed an increase in the number of dead cells in a section of medulla as compared with controls (8), and a modified pattern of seizure activity induced by electroshock treatment during the first five postnatal weeks (5). Other reports described that pups from mothers exposed to nicotine during pregnancy showed underweight at birth (6,13), fewer live young were born and mothers delivered their pups later and gained less weight during pregnancy (2,3). Alterations in neuronal pathways at both central and peripheral levels have also been reported (14). Since neuronal alterations are frequently observed among the deleterious effects induced by prenatal nicotine exposure, we studied the seizure susceptibility to ECS in adult offspring of rats treated with a mild nicotine dosage during pregnancy. In addition, different behavioral and developmental parameters were also measured in mothers and pups during pregnancy and after delivery from control and experimental groups.
spermatozoa in the vaginal smear) until day 20 of gestation. Nicotine was administered at 0900 and 1700 h. The control group received saline at the same volume (0.1 ml/100 g b.wt.). Animals were maintained at 22---2°C in a 12-h light-dark cycle (light on at 0700 h). Food and water were available ad lib. The mean duration of gestation and the number of living young were recorded from experimental and control rats. Some aspects of maternal behavior, such as nest building and retrieval (1,4), were also recorded (e.g., Table 1). Several developmental parameters (9) that may have been affected by nicotine exposure during fetal life were also recorded in the pups.
Seizure Testing Adult male and female rats from both groups (experimental and control), 9-10 months old, were used in order to determine the seizure threshold to ECS. Seizure susceptibility was measured using an Electroconvulsive Treatment Unit (Ugo Basile, Varese, Italy) by means of ear electrodes. The ECS intensities applied (0.4-s duration) ranged between 35 and 60 mA (35, 40, 45, 50, 55 and 60) for females and between 50 to 85 mA (50, 55, 60, 65, 70, 75, 80 and 85) for male rats. Experimental and control rats received an ECS daily ramdomly. Results were expressed as the probability of having a convulsion. Seizure was defined by the presence of tonic and/or clonic movements of at least 5-s duration accompanied by loss of the righting reflex. The test was performed in a quiet room from 1400 to 1700 h.
METHOD Female pregnant rats (Wistar strain), kept in individual Plexiglas cages, were injected twice a day with nicotine (1 mg/kg SC) from the first day of pregnancy (identified by the presence of
Statistical Methods Differences between experimental and control data related to
271
272
BRITOS AND ORSINGHER
TABLE 1
100,
Control
A
Experimental
.
0892-0362/91 $3.00 + .00
Prenatal Nicotine Exposure Increased Susceptibility to Electroconvulsive Shock (ECS) in Adult Rats S E R G I O A. B R I T O S A N D O T T O A. O R S I N G H E R
Departamento de Farmacologfa, Facultad de Ciencias Quimicas, Universidad Nacional de Crrdoba Sucursal 16, C. C. 61, 5016, Cdrdoba, Argentina R e c e i v e d 1 O c t o b e r 1990
BRITOS, S. A. AND O. A. ORSINGHER. Prenatal nicotine exposure increased susceptibility to electroconvulsive shock (ECS) in adult rats. NEUROTOXICOL TERATOL 13(3) 271-273, 1991.--Female rats were treated during pregnancy (days 1-20) with nicotine (1 mg/kg SC, b.i.d.). When some aspects of maternal behavior and developmental parameters were recorded in mothers and pups, respectively, no changes were detected in the experimental group as compared with controls. However, adult offspring of nicotine-treated rats showed an increased susceptibility to ECS. These results demonstrate long-lasting deleterious effects induced by nicotine exposure during fetal life. Prenatal nicotine exposure
Electroconvulsive shock
DIFFERENT lines of evidence, arising from experimental and clinical fields, have pointed to deleterious effects induced by prenatal nicotine exposure. Maternal smoking represents a high risk factor for sudden infant death syndrome (8,11), and it is also involved in the pathogeny of other functional disorders, such as Minimal Brain Disfunction, locomotive and growth retardation as well as learning impairment (11). Different experimental models have been used in order to assess the deleterious effects induced by perinatal nicotine administration. Offspring of rats treated with nicotine during pregnancy revealed an increase in the number of dead cells in a section of medulla as compared with controls (8), and a modified pattern of seizure activity induced by electroshock treatment during the first five postnatal weeks (5). Other reports described that pups from mothers exposed to nicotine during pregnancy showed underweight at birth (6,13), fewer live young were born and mothers delivered their pups later and gained less weight during pregnancy (2,3). Alterations in neuronal pathways at both central and peripheral levels have also been reported (14). Since neuronal alterations are frequently observed among the deleterious effects induced by prenatal nicotine exposure, we studied the seizure susceptibility to ECS in adult offspring of rats treated with a mild nicotine dosage during pregnancy. In addition, different behavioral and developmental parameters were also measured in mothers and pups during pregnancy and after delivery from control and experimental groups.
spermatozoa in the vaginal smear) until day 20 of gestation. Nicotine was administered at 0900 and 1700 h. The control group received saline at the same volume (0.1 ml/100 g b.wt.). Animals were maintained at 22---2°C in a 12-h light-dark cycle (light on at 0700 h). Food and water were available ad lib. The mean duration of gestation and the number of living young were recorded from experimental and control rats. Some aspects of maternal behavior, such as nest building and retrieval (1,4), were also recorded (e.g., Table 1). Several developmental parameters (9) that may have been affected by nicotine exposure during fetal life were also recorded in the pups.
Seizure Testing Adult male and female rats from both groups (experimental and control), 9-10 months old, were used in order to determine the seizure threshold to ECS. Seizure susceptibility was measured using an Electroconvulsive Treatment Unit (Ugo Basile, Varese, Italy) by means of ear electrodes. The ECS intensities applied (0.4-s duration) ranged between 35 and 60 mA (35, 40, 45, 50, 55 and 60) for females and between 50 to 85 mA (50, 55, 60, 65, 70, 75, 80 and 85) for male rats. Experimental and control rats received an ECS daily ramdomly. Results were expressed as the probability of having a convulsion. Seizure was defined by the presence of tonic and/or clonic movements of at least 5-s duration accompanied by loss of the righting reflex. The test was performed in a quiet room from 1400 to 1700 h.
METHOD Female pregnant rats (Wistar strain), kept in individual Plexiglas cages, were injected twice a day with nicotine (1 mg/kg SC) from the first day of pregnancy (identified by the presence of
Statistical Methods Differences between experimental and control data related to
271
272
BRITOS AND ORSINGHER
TABLE 1
100,
Control
A
Experimental
.
