Evaluation of effects of photooxidized Vespa orientalis venom on memory and learning in rats

Wasp venom is mixture of complex proteins that have several physical and pharmacological properties. The photochemical detoxification of Vespa orientalis venom is expected to generate photooxidized venom sac extract (PVSE). Antigenically active PVSE is obtained by exposing the venom sac extract (VSE) of Vespa orientalis to ultraviolet radiation in the presence of methylene blue. The aim of the present work was to evaluate the effect of PVSE on learning and memory of rats. Detoxification of PVSE was evident since treated mice had longer survival time than the group of mice treated with VSE. Photooxidized VSE of V. orientalis revealed enhancement on learning and memory by shortening the time to reach food (TRF) in T-maze. In a 28-day study with rats, we observed that PVSE significantly decreased transfer latency (TL) in elevated plus maze (EPM), significantly increased step down latency (SDL), diminished step down errors (SDE) and time spent in shock zone (TSS) in step down avoidance test. Thus, we concluded that although there is a possibility of employing PVSE in the treatment of Alzheimer, dementia or neurodegenerative illness as a non-herbal and non-synthetic alternative for patients who do not respond to available therapy, further investigation is still required.(AU)

Evaluation of the effects of photooxidized Echis carinatus venom on learning, memory and stress

Snake venoms are a mixture of complex proteins, which have many physical and pharmacological properties. Photochemical detoxification has been suggested to generate photooxidized Echis carinatus venom product (POECVP). Antigenically-active photooxidized species of Echis carinatus venom could be obtained by exposing the venom to ultraviolet radiation (UVR) in the presence of methylene blue. The aim of the present study was to evaluate the effects of POECVP on learning, memory and stress in rats. Detoxification of the photooxidized venom was evident since the POECVP-treated group had longer survival time than the group of mice treated with Echis carinatus venom product (ECVP) following intraperitoneal and intracerebral injections. Photooxidized Echis carinatus venom product showed antidepressant activity by prolonging sleep onset and shortening the duration of pentobarbitone-induced hypnosis in mice. In single and chronic dose studies with rats, we observed that POECVP significantly decreased the time needed to reach food in T-maze, shortened transfer latency in elevated plus-maze, and decreased immobility time in forced swim test. We concluded that although there is a possibility of employing POECVP in the treatment of depressive and chronic degenerative illnesses as a nonherbal and nonsynthetic alternative for patients not responding to the available therapy, further investigation is still needed.(AU)

Comparative evaluation of mechanism of neuromuscular (n-m) blockade due to enhydrotoxin-A (EsNTx-a) and D-tubocurarine (d-TC).

Effects of major E. schistosa neurotoxin (NTx) EsNTx-a are compared with plant alkaloid d-TC for its onset (LP) and duration of action as the time required for 50% n-m blockade (DT1/2) in normal Ca2+ and modified Ca2+ Krebs Heinsleit (K-H) at two different (low and high) concentrations (conc.). Toxin-EsNTx-a in low Ca2+ K-H and d-TC in both normal and modified Ca2+ K-H did not show LP, whereas LP is increased significantly in 2 Ca2+ K-H in high conc. of EsNTx-a. DT1/2 is increased significantly in high conc. of EsNTx-a and in low conc. of d-TC in 2 Ca2+ K-H. N-m blocking actions are further compared with alpha-bungarotoxin (alpha-BuTx), beta-bungarotoxin (beta-BuTx), and botulinum toxin (B-Tx) for their effects on tetanus, Wednesky inhibition (W.I.), and post tetanic potentiation (PTP).

The effect of venom from the Indian tropical wasp Vespa tropica on nerve-muscle preparations from Drosophila larvae.

The action of the venom of Vespa tropica on spontaneous and evoked release of excitatory neurotransmitter at the larval neuromuscular junction of Drosophila melanogaster was studied. The frequency of spontaneous miniature end plate potentials in venom treated nerve-muscle preparation falls rapidly after treatment, while the m.e.p.p. amplitude decreases to about 50% after 6 min of treatment with 1.2 X 10(-5) g of the venom per ml. The end plate potential decreased steadily while the resting membrane potential was less affected. The paralysed preparation did not recover, even after extensive washing.

Isolation and characterisation of toxic components from the venom of the common Indian sea snake (Enhydrina schistosa).

Three neurotoxic components, enhydrotoxins a, b and c, were isolated by a three step procedure from the venom of the sea snake Enhydrina schistosa, caught in the Arabian sea. The i.v. LD50 values in mice were 0.042, 0.045 and 0.052 mg/kg, respectively. All three toxins irreversibly blocked neuromuscular transmission. Abolition of responses to acetylcholine indicated a post-synaptic site of action of these toxins. The molecular weight and amino acid composition of enhydrotoxin a are similar to values earlier reported for Enhydrina toxins.