ABSTRACT
Objective To investigate the effect of exogenous GAs on learning and memory capability of hypoxic-ischemic(HI) brain damage rats. Methods After ligation of the right carotid artery of 7-day old male SD rats and waiting for 4 hours of recovery, the rats were exposed to 8% oxygen-92% nitrogen gas mixture for 2 hours. The HI animals were randomly divided into 3 groups. GAs-treated group 1: animals were injected i.p. GAs immediately after HI every 12 hours for 4 doses with 50 mg/kg, followed by a 2 weeks consecutive daily injections at dose of 30 mg/kg/day. GAs treated group 2: rats received GAs 50 mg/kg immediately after HI every 12 hours for 4 doses, followed by injection of saline in the same volums for 2 weeks. Control group: rats received saline in the equivalent volums and duration. The behavioral test starded when the animals were 24 days old. Discriminative learning ability and memory retention were tested in the tri-equal-arms maze . The locomotor activity and alternative behavior was observed. The degree of neuronal damage were assessed after behavioral test. Results (1)The number of trails to reach the learning criteria were (39?17), (32?14)and (20?13) for control group, GAs-treated group 2 and GAs-treated group 1, respectively. The percentages of memory retention for control group, GAs-treated group 2 and GAs-treated group 1 were (62?10)%, (64?11)% and (70?9)%, respectively. Two weeks consecutive daily injection of GAs had facilitatory effects on learning ability and memory retention of HI rats(P0.05). Conclusion Gangliosides can enhance the learning ability and memory retention in neonate rats with HI.
ABSTRACT
Kainic acid (KA) is now being widely used in neurobiology as a lesioning tool but, until recently, no neurohistological studies had been done on rabbits. The present study was undertaken to investigate the effect of kainic acid on hippocampal and caudate neurons in adult and young rabbits.Our results were as follows:1. Intraventricular injection of 0.8 ?g of KA caused destruction of the most of pyramidal cells in CA_3 and CA_4 in adult rabbits. At the same time damage to caudate neurons was also observed. After injection of 0.3 of 0.5 ?g of KA approximately one half of neurons in CA_3 and CA_4 was destroyed. Injection of KA with higher dose (1 ?g) caused more extensive damage to hippocampal neurons. However, after intraventricular injection of KA (0.1 or 0.2 ?g) in young rabbits (15～18 days old), the damage to some pyramidal ceils was observed only in CA_3a.2. Injection of 0.3 ?g KA into rabbit hippocampus caused destruction of neurons confined to the injected area. Intracaudate injection of KA with same dose (0.3 ?g) caused a small loss of caudate neurons, and the damage seemed less extensive.It was suggested that given proper care, KA can be also used to lesion selectively most perikarya in rabbit brain area.