Effect of late treatment with gamma-hydroxybutyrate on the histological and behavioral consequences of transient brain ischemia in the rat.

It has been previously described that gamma-hydroxybutyrate (GHB) provides significant protection against transient global cerebral ischemia in the rat (four vessel occlusion model), when given 30 min before or 10 min after artery occlusion. Here, we show that in the same rat model, significant protection can also be obtained when treatment is started 2 h after the ischemic episode. In saline-treated animals, 30 min of global ischemia followed by reperfusion caused a massive loss of neurons in the hippocampal CA1 subfield (examined 63 days after the ischemic episode), and an impairment of sensory-motor performance (tested on the 51st and 63rd days after ischemia) and of spatial learning and memory (evaluated starting 46 days after the ischemic episode). Treatment with GHB--300 mg/kg intraperitoneally (i.p.) 2 h after the ischemia-reperfusion episode, followed by 100 mg/kg i.p. twice daily for the following 10 days--afforded a highly significant protection, against both histological damage and sensory-motor and learning-memory impairments. These data further suggest the possible therapeutic effectiveness of GHB in brain ischemia, and indicate that the underlying mechanism of action involves non-immediate steps of the ischemia-induced cascade of events.

Effect of gamma-hydroxybutyrate in two rat models of focal cerebral damage.

Gamma-hydroxybutyrate (GHB) and its lactone, gamma-butyrolactone (GBL) have been previously shown to produce a protective effect in animal models of cerebral ischaemia/hypoxia, as well as in human conditions of head injury-induced coma. The aim of the present research was to study the effect of GHB in experimental conditions of focal cerebral damage, either induced by ischaemia or excitotoxicity. Under general anaesthesia, rats were injected into the right striatum with either endothelin-1 (ET-1, 0.43 nmol) or kainic acid (7.5 nmol) in a volume of 1 microl. Sham-lesioned rats received 1 microl of the solvent. Both ET-1- and kainic acid-lesioned rats were randomly assigned to one of the following intraperitoneal (i.p.) treatments: (i) and (ii) GHB, 100 or 300 mg kg(-1) 2 h after the lesion, followed by 50 or 100 mg kg(-1), respectively, every 12 h; (iii) saline, 2 ml kg(-1), same schedule. Sham animals were treated with saline, 2 ml kg(-1), same schedule. Treatments lasted for 10 days. The higher dose of GHB produced a significant protection against the ET-1-induced impairments in sensory-motor orientation and coordinated limb use (evaluated 24 and 42 days after the lesion) and in place learning and memory (Morris test, performed 19 and 39 days after the lesion). The same dose regimen reduced the circling behaviour induced by apomorphine in kainate-lesioned rats (10 days after the lesion), and limited or prevented at all the histological damage produced either by ET-1 or by kainic acid (evaluated 43 or 10 days after the lesion, respectively). These results show that GHB limits both histological and functional consequences of a focal ischaemic or excitotoxic insult of the brain, in rats, even if the treatment is started 2 h after the lesion.

Molecular characterization of a defensin in the IZD-MB-0503 cell line derived from immunocytes of the insect Mamestra brassicae (Lepidoptera).

The induction of anti-microbial peptides against Gram positive and negative bacteria in the IZD-MB-0503 cell line from the lepidopteran Mamestra brassicae is demonstrated, while no anti-fungal activity is detected. The identification of a defensin-like molecule active against Gram positive bacteria is described for the first time in Lepidoptera. This molecule shows between 43% and 59% homology with group A defensins from other dipteran and hymenopteran species.