NEUROBEHAVIORAL ASSAY OF ETHANOL EXTRACT OF CROTON LOBATUS (EUPHORBIACEAE) LEAVES IN MICE

Abstract

Background: Neurobehavioural activity exhibition by an extract or compound is an indicator of
the ability of its phytoconstituents to cross the blood brain barrier and modulate neurochemicals
implicated in behaviours such as novelty induced behaviours, locomotion, anxiety and memory.
The modulation may in part but not exclusive limited to inhibition/enhancement of enzymatic
activity in the synthesis pathway of neurotransmitters or receptor blockade/mimicry activity.
Aim: To investigate the neurobehavioral properties and possible neural mechanisms of Croton
lobatus in mice.
Methods: The neurobehavioral properties were assessed using the open field for novelty-induced
rearing (NIR) and grooming (NIG), and locomotor activity in mice, while the hole board
apparatus for the frequency of head dip. The Y-maze was used for short-term working memory,
and the elevated plus maze (EPM) for anxiety as indexed by the open arm avoidance.
Mechanistic studies were conducted with atropine, cyproheptadine, haloperidol and propranolol.
Results: The median lethal dose (LD50) of Croton lobatus was 1444 mg/kg, i.p. Croton lobatus
at 5, 10, 20 and 40 mg/kg, i.p significantly dose dependently reduced novelty induced behaviors.
On the Y-maze no significant change in the percentage alternation on short-term working
memory was observed, while on the elevated plus maze a high index of open arm avoidance was
obtained. These results confirm the central nervous system depressant properties of Croton
lobatus, which may be mediated through α-2 adrenoceptor.
Conclusion: Croton lobatus possess sedative property and it may be mediated through α-2
adrenoceptor system.