Evaluation of vegetal extracts as biological herbi- and pesticides for their use in Cuban agriculture.

The idea of an interuniversity project between the Universidad Central de Las Villas, Cuba and the University of Ghent, Belgium was conceived in order to improve the quality of the Cuban agriculture and to stimulate its independence from foreign chemical farm inputs, starting with an applied ethnobotanical investigation as basis for the development of sustainable agricultural practices. The project consists of three parts. The first, ethnobotanical part, subtends the two subsequent stages, i.e. the phytochemical and pharmacological stages. After ethnobotanical inventarization of plants with a possible phytotoxic or pesticide effect, these will be collected and taxonomically defined. Fresh vegetal material will be dried and ground, and this first crude extract (polar or apolar) will be tested for its activity in in vitro biological tests. When results are positive (presence of activity), this crude extract will be tested in vivo, which could lead to immediate application in agriculture (short-term strategy). The long-term strategy will lead to the identification of chemical substances, responsible for the activity of the crude extract. As highly sophisticated apparatus is needed for this last step (i.e. identification of chemical compounds), this will be performed by the Department of Organic Chemistry, Faculty of Agricultural and Applied Biological Sciences of the University of Ghent. The project has started in September 2000. Apart from all the (complicated) administrative steps to be undertaken for its successful execution, the ethnobotanical and phytochemical parts have already started. Ethnobotanical data were gathered in view of recollection of "traditional botanical knowledge", considering three main approaches: the use of plants in medicine, in Cuban religion (the famous "santería") and the use of allelopathic plants in agriculture. Use of medicinal and religious plants is ubiquitous in Cuba. The concept of allelopathy, however, is much less known and applied. At this moment, and after preliminary screening and gathering of field data, in vitro germination tests are running, trying out extracts of tobacco (Nicotiana tabacum), banana (Musa spp.), sunflower (Helianthus annuus), Simarouba glauca and S. laevis (syn. Quassia, fam. Simaroubaceae).

A stereotaxic atlas of the forebrain of the bank vole (Clethrionomys glareolus).

In this article part of the forebrain of the bank vole (Clethrionomys glareolus) is presented in stereotaxic coordinates. The stereotaxic procedure was performed as follows. With the vole's head mounted in a stereotaxic adaptor, internal reference tracks were made with a 0.5-mm diameter microdialysis cannula and India ink, 2 mm in front and 2.6 mm behind the skull landmark bregma. Brains were fixed for 72 h in 4% commercial formaldehyde in sodiumcacodylate buffer containing 1% CaCl2. To determine shrinkage they were weighed before and after fixation. After embedding in paraffin they were sectioned at 25 microm and stained with Nissl. Photomicrographs were taken from the brain of one animal while its frontal (antero-posterior) coordinates of five neural structures were compared with those of 12 other voles. Variability was also checked in lateral and vertical directions at frontal level -1.0 mm (relative to bregma). The results show that the distance between the two skull landmarks bregma and lambda correlates significantly and negatively with the antero-posterior position of each of the brain areas. On the basis of these results an equation is proposed to improve accuracy in locating neural structures that deviate due to biological variability.

Dissociation between MK-801- and captivity-induced stereotypies in bank voles.

Pharmacologically induced stereotypies (PHIS) following dopamine agonists and, more recently, the non-competitive NMDA antagonist dizocilpine (MK-801), are used to study human psychopathology and for screening potential neuroleptic drugs. On the other hand, bank voles (Clethrionomys glareolus) spontaneously develop stereotyped jumping in barren cages, already before the age of 1 month (= captivity-induced stereotypies or CIS). Large interindividual differences in the level of jumping exist. In this study, the effect of MK-801 on various behaviours of bank voles, and in particular the relationship between CIS and PHIS, was investigated by repeated administration of MK-801 to stereotyping (ST) and non-stereotyping (NST) voles. The animals received nine daily s.c. injections of, respectively, saline and 0.3 mg/kg MK-801, with a 48-h break between both treatments. Their behaviour was visually recorded every 4 days. The results showed that jumping was neither evoked in NST, nor intensified in ST. Instead, in both ST and NST, PHIS consisting of intensive sniffing and locomotor stereotypy characterised by running in unidirectional circles were elicited. Furthermore, ST showed behavioural sensitisation for locomotor stereotypy, while in NST intensive sniffing was progressively enhanced. These results suggest that CIS and PHIS induced by MK-801 in bank voles are regulated, at least in part, by different neuronal mechanisms and that ST and NST could be predisposed to develop more easily one given PHIS than the other.

Effect of apomorphine on the conflict-induced jumping stereotypy in bank voles.

In conventional laboratory cages, bank voles (Clethrionomys glareolus) develop a jumping up-and-down stereotypy already before the age of one month. Central DA systems are thought to be involved in the expression of these conflict-induced stereotypies (CIS). Stereotypies can also be elicited pharmacologically, most commonly by amphetamine and apomorphine. Hence, administration of apomorphine to jumping bank voles provides the opportunity to compare pharmacologically-induced stereotypies (PHIS) and CIS in that species. A pilot study showed that apomorphine induced stereotyped licking that is qualitatively different from the CIS elicited by captivity. The present study investigated whether apomorphine has an effect on CIS-levels. The lowest dose (0.625 mg/kg) did not elicit licking but neither influenced jumping levels. Higher doses (0.938 and 1.094 mg/kg) lead to the occurrence of licking but also suppressed CIS-levels. However, the discordance in time profiles of licking and jumping argues against a shift from jumping to licking due to further stimulation of already activated DA systems. Therefore, expression of jumping seems to depend on stimulation of other DA receptor subtypes or jumping may even be DA independent.

A combined stereotaxic adaptor and anaesthesia apparatus for microdialysis studies in small rodents.

Intracerebral microdialysis in the bank vole (Clethrionomys glareolus) challenges the accuracy and precision of the stereotaxic implantation technique because of the small brain size. In this paper, a miniaturized stereotaxic head holder is described that allows precise alignment of bone landmarks on the skull and prevents all movement after fixation by clamping the skull symmetrically at the os parietale and at the os nasale. In addition, the head holder is adapted for inhalation anaesthetic delivery in order to ensure stable anaesthetic depth over several hours. The system is not restricted to bank voles but can be readily applied to other small experimental animals, which could lead to a more widespread use of the microdialysis technique in mice.