001P London, UK
8th European Workshop on Cannabinoid Research

 

 

Perinatal neuroprotection of cannabidiol-treated developing rats after repeated bicuculline-induced seizures

F. J. Alvarez1, H. Lafuente1, A. A. Alvarez2, E. Hilario2, W. Hind3, J. Martinez-Orgado4. 1Biocruces Institute, Cruces University Hospital, Barakaldo, Spain, 2Cell Biology and Histology, University of the Basque Country, Leioa, Spain, 3GW Research, Histon, Cambridge, United Kingdom, 4Instituto del Niño y del Adolescente (INA), Hospital Clínico "San Carlos" - IdISSC, Madrid, Spain.

Introduction: Seizures represent a frequent adverse neurological event in newborns, causing brain damage with long-lasting impairment of cognition and behavior1. Since cannabidiol (CBD) has demonstrated neuroprotection in experimental neonatal hypoxic-ischemic brain damage2, our aim was to test whether early CBD treatment improves long-term neuroprotective outcome of developing rats exposed to bicuculline-induced seizures.

Method: Rat pups (P5) received bicuculline as seizure inductor during three consecutive days at 2-4 mg/kg intraperitoneal dose3. Pups were randomized to receive placebo solution (VEH group) or CBD (GW Research, Cambridge UK) at 1, 10 and 100 mg/kg/day for 3 days (CBD1, CBD10, CBD100 groups). Pups without seizure or drug treatment were used as reference (SHAM group). Brain damage was assessed at juvenile stage (P37) in function of neuropathological score4 (hippocampus and cortex), electroencephalography and cognitive deficit (sensori-motor tests: RotaRod, cylinder rearing test; learning & memory tests: T-maze, novel object recognition). Data are given as mean±SEM (sample size). Analysis was performed using Kruskal-Wallis test with Dunn's correction.

Results: Data of P37 rats with seizure brain damage and CBD treatment are summarized in table 1.

(a) p<0.05 vs. SHAM; (b) p<0.05 vs. VEH; (c) p<0.05 vs CBD1; (d) p<0.05 vs CBD10
Table 1 SHAM VEH CBD1 CBD10 CBD100
Neuropathological score:
hippocampus		 0.4±0.3
(10)		 2.1±0.2a
(10)		 1.9±0.2a
(10)		 1.5±0.2a,b
(10)		 0.6±0.3b,c,d
(10)
Neuropathological score:
cortex		 0.4±0.3
(10)		 2.4±0.3a
(10)		 2.3±0.3a
(10)		 1.9±0.3a
(10)		 0.8±0.2b,c,d
(10)
Electroencephalography
(μV)		 18±1
(10)		 15±1a
(20)		 15±2
(20)		 16±2
(20)		 17±2
(20)
Rotarod:
latency to fall (sec)		 259±12
(10)		 189±14a
(20)		 207±10a
(20)		 216±21a
(20)		 234±9b,c
(20)
Cylinder rearing test:
preference for left (%)		 -0.3±0.5
(10)		 1.8±1.9
(20)		 -0.3±1.4
(20)		 0.9±2.6
(20)		 0.5±1.4
(20)
T-maze:
correct response (%)		 64±8
(10)		 36±9a
(20)		 43±10a
(20)		 50±5
(20)		 52±5b
(20)
Novel object recognition:
discrimination index		 0.52±0.02
(10)		 0.40±0.04a
(20)		 0.41±0.04a
(20)		 0.47±0.02a,b
(20)		 0.50±0.02b,c
(20)

 

Bicuculline-treated pups showed tonic-clonic seizures after 10 min, which continued for 1.5- to 2 hours. VEH group developed a long-term bicuculline-induced functional impairment, as observed in the neuropathology, electroencephalography and neurobehavioral tests. CBD treatment partially reversed neurophysiological and neurofunctional sequelae of seizures.

Conclusion: Bicuculline-induced repetitive seizure in neonatal period produced a long-term functional impairment, which was evident at juvenile stage. Although, the bicuculline model did not induce significant alterations compared to sham for some of the parameters, a clear neuroprotective role of CBD was present at 100 mg/kg, maintaining structural and functional brain parameters (histology, learning, memory, motor coordination). Also, limited improvements were observed at 10 mg/kg CBD dose.

References:

1. Ronen GM et al. (2007). Neurology 69: 1816-1822.

2. Alvarez FJ et al. (2008). Pediatr Res 64: 653-658.

3. Doriat JF et al. (1998). Brain Res 800: 114-124.

4. Pazos MR et al. (2012). Neuropharmacology 63: 776-783.