Karwinskia Humboldtiana Research Articles

Conduction block and functional denervation caused by Tullidora ( Karwinskia humboldtiana)

Cats treated with ether extracts from the fruit of Tullidora ( Karwinskia humboldtiana) developed paralysis of the hind limbs starting 3 to 6 weeks after a single oral dose. The purpose of these experiments was to elucidate the mechanisms underlying the paralysis. The medial gastrocnemius and soleus muscles of paralyzed hind limbs showed mechanical properties similar to those observed after denervation. When motor nerves of treated animals were stimulated close to their muscles, the twitch tensions were as large as the twitch tension produced by direct stimulation of the muscles. In contrast, the twitches elicited by stimulation of the ventral roots were considerably reduced. These findings suggested conduction block in peripheral nerves. The postulated conduction block was investigated in cutaneous (sural) and motor (medial gastrocnemius) nerves. Potentials elicited in the sural nerve decreased in amplitude and area as the distance between stimulating and recording electrodes increased. This potential reduction was more prominent toward the periphery. The action potentials produced in the medial gastrocnemius nerve by ventral root stimulation were also reduced compared to control animals. Electron microscopy revealed intense demyelination in motor nerves and increased density of neurofilaments. Demyelination was not observed in the ventral roots. It is postulated that the observed conduction block is a consequence of demyelination.

Buckthorn neuropathy: effects of intraneural injection of Karwinskia humboldtiana toxins.

Ingestion of the endocarp of the coyotillo fruit, Karwinskia humboldtiana, a shrub of the buckthorn family, causes "Buckthorn neuropathy" in man and animals. Two neurotoxic compounds T496 and T544 were isolated from the endocarp and each toxin was dissolved in sesame oil and injected into the sciatic nerve of rats. The nerves were subsequently examined by teasing and as sections by light and electron microscopy. During the first 3--4 days after injection, oil droplets, probably containing toxin, were observed in the cytoplasm of Schwann cells with intact myelin sheaths. Clinical signs of weakness in the limb first appeared at 5--6 days and were accompanied by segmental demyelination mainly of the larger fibres. These observations suggest that the toxins have a primary action on Schwann cell metabolism. The results of local injection of purified toxins are discussed in relation to reports of nerve damage in animals following oral administration of the endocarp where intramyelin vacuole formation and segmental demyelination are prominent features.

870. Muscle damage by coyotillo fruit: Dewan, M. L., Henson, J. B., Dollahite, J. W. & Bridges, C. H. (1965). Toxic myodegeneration in goats produced by feeding mature fruits from the coyotillo plant ( Karwinskia humboldtiana). Am. J. Path.46, 215

870. Muscle damage by coyotillo fruit: Dewan, M. L., Henson, J. B., Dollahite, J. W. & Bridges, C. H. (1965). Toxic myodegeneration in goats produced by feeding mature fruits from the coyotillo plant ( Karwinskia humboldtiana). Am. J. Path.46, 215