Biomedical subjects

F Berrendero

Publications and source records attributed to F Berrendero.

23 records · Page 2Linked to original sources

PubMed1998

Loss of cannabinoid receptor binding and messenger RNA levels and cannabinoid agonist-stimulated [35S]guanylyl-5'O-(thio)-triphosphate binding in the basal ganglia of aged rats.

Recent reports have demonstrated that cannabinoid receptor binding decreases in several neurodegenerative diseases related to extrapyramidal function. However, there is little evidence with regard to potential changes of these receptors during senescence. The present study was designed to determine the possible existence of ageing-induced changes in cannabinoid receptor binding and gene expression in extrapyramidal areas. To this end, we analysed cannabinoid receptor binding and basal and cannabinoid receptor agonist-stimulated [35S]guanylyl-5'-O-(gamma-thio)-triphosphate binding, by using autoradiography, and cannabinoid receptor messenger RNA levels, by using in situ hybridization, in slide-mounted brain sections obtained from young (three-month-old) and aged (>two-year-old) rats. Results were as follows. Aged rats exhibited a marked decrease in cannabinoid receptor binding in most of the basal ganglia, excepting the globus pallidus which had similar binding levels in both young and aged rats. The highest decreases were in the entopeduncular nucleus (-49.6%) and substantia nigra pars reticulata (-45.2%), whereas more moderate decreases were found in the lateral caudate putamen (-29%) and only a decremental trend in the medial caudate putamen (-13.1%). These decreases in cannabinoid receptor binding were paralleled by less marked increases in WIN 55212-2-stimulated [35S]guanylyl-5'-O-(gamma-thio)-triphosphate binding in these structures in aged rats (% of agonist stimulation: 189% in the substantia nigra; 29.4% in the lateral caudate putamen) as compared to young rats (296% and 53.2%, respectively). Contrarily, the percentage of agonist stimulation was similar in the globus pallidus, an area where cannabinoid receptor binding did not change during ageing, of aged (205.5%) and young (215.5%) rats. In addition, aged rats also exhibited significant reductions in the cannabinoid receptor messenger RNA levels in the medial (-14.3%) and, in particular, in the lateral (-29.4%) caudate putamen, the area where the cell bodies of cannabinoid receptor-containing neurons, projecting to the substantia nigra, entopeduncular nucleus and globus pallidus, are located. In summary, the synthesis and binding levels of cannabinoid receptors markedly dropped in different structures of the extrapyramidal system of aged rats. Since these receptors, located in the basal ganglia, seem to play a role in motor control, this loss of cannabinoid receptors might be related to the motor impairment which progressively appears during senescence.

Aging↗

PubMed1998

Localization of mRNA expression and activation of signal transduction mechanisms for cannabinoid receptor in rat brain during fetal development.

In the present work, we analyzed cannabinoid receptor mRNA expression, binding and activation of signal transduction mechanisms in the fetal rat brain or in cultures of fetal neuronal or glial cells. Cannabinoid receptor binding and mRNA expression were already measurable at GD14, but they were only located in discrete regions at GD16. Among these, the hippocampus, the cerebellum and the caudate-putamen area, three regions that contain a marked signal for both binding and mRNA in the adult brain. Significant levels of binding and, in particular, of mRNA transcripts were also detected at GD16 in the cerebral cortex, midbrain and brainstem. These structures contain relatively low levels of binding and mRNA in the adult brain, suggesting that cannabinoid receptor gene is transiently expressed in atypical areas during the fetal period. The signal for cannabinoid receptor mRNA in the hippocampus, caudate-putamen and cerebral cortex progressively increased from GD16 up to GD21. At GD18 and GD21, mRNA transcripts could be measured in discrete nuclei, such as septum nuclei, ventromedial hypothalamic nucleus and others. The cerebral cortex exhibited the highest mRNA levels at GD21, although this was not accompanied by a parallel increase in binding. An important aspect is that binding measured at these ages represent binding to functional receptors because their activation by WIN-55,212-2 increased [35S]GTPgammaS binding in the same areas. This increase was reversed by a specific antagonist, SR141716. The areas where the stimulation was more marked were the midbrain and brainstem. Using cell cultures, we have observed that cannabinoid receptor mRNA is present in cortical and hippocampal neuronal cells, but not in the glial cells. However, WIN-55,212-2 was capable of stimulating [35S]GTPgammaS binding in membrane fractions obtained from cortical glial cells and this stimulation was reversed by SR141716. This was not seen with hippocampal glial cell cultures, but occurred in hippocampal and cortical neurons. In addition, the activation of these receptors with Delta9-tetrahydrocannabinol significantly reduced forskolin-stimulated cAMP production in cortical neuronal or glial cell cultures and this effect was reversed by SR141716. In summary, we have detected cannabinoid receptor binding, mRNA expression and activation of signal transduction mechanisms in the fetal rat brain (GD14-GD21), which support the view that the system constituted by these receptors and their putative endogenous ligands might play a role in specific molecular events of the brain development. Of relevance is that binding and mRNA expression appear atypically distributed in the fetal brain as compared with the adult brain, even, that their presence in white-matter-enriched areas might presumably indicate their location in non-neuronal cells. These studies with cell cultures suggest that CB1 receptor subtype is located in neuronal cells obtained from fetal brain, although preliminary evidence is provided of the existence of another receptor subtype operative in glial cells obtained from the cerebral cortex.

Animals↗

PubMed1998

Cannabinoid receptor and WIN-55,212-2-stimulated [35S]GTP gamma S binding and cannabinoid receptor mRNA levels in the basal ganglia and the cerebellum of adult male rats chronically exposed to delta 9-tetrahydrocannabinol.

The inhibition of motor behavior in rodents caused by the exposure to plant or synthetic cannabinoids has been reported to develop tolerance after repeated exposure. This tolerance seems to have a pharmacodynamic basis, since downregulation of cannabinoid receptors in motor areas, basal ganglia and cerebellum, has been demonstrated in cannabinoid-tolerant rats. The present study was designed to further explore this previous evidence by analyzing simultaneously in several motor areas of delta 9-tetrahydrocannabinol- (delta 9-THC)-tolerant rats: 1. Cannabinoid receptor binding, by using [3H]WIN-55,212-2 autoradiography; 2. Cannabinoid receptor activation of signal transduction mechanisms, by using WIN-55,212-2-stimulated [35S]-guanylyl-5'-O-(gamma-thio)-triphosphate ([35S]-GTP gamma S) autoradiography; 3. Cannabinoid receptor mRNA expression, quantitated by in situ hybridization. Results were as follows. As expected, the exposure to delta 9-THC for 5 d resulted in a decrease of cannabinoid receptor binding in the molecular layer of the cerebellum, medial, and lateral caudate-putamen and, in particular, entopeduncular nucleus. We also found decreased cannabinoid receptor binding in the superficial and deep layers of the cerebral cortex, two regions used as a reference to test the specificity of changes observed in motor areas. There were only two brain regions, the globus pallidus and the substantia nigra, where the specific binding for cannabinoid receptors was unaltered after 5 d of a daily delta 9-THC administration. However, in the substantia nigra, the magnitude of WIN-55,212-2-stimulated [35S]-GTP gamma S binding was lesser in delta 9-THC-tolerant rats than controls, thus suggesting a possible specific change at the level of receptor coupling to GTP-binding proteins. This was not seen neither in the globus pallidus nor in the lateral caudate-putamen, where agonist stimulation produced similar [35S]-GTP gamma S binding levels in delta 9-THC-tolerant rats and controls. Finally, animals chronically exposed to delta 9-THC also exhibited a decrease in the levels of cannabinoid receptor mRNA in the medial and lateral caudate-putamen, but there were no changes in the cerebellum (granular layer) and cerebral cortex. In summary, the chronic exposure to delta 9-THC resulted in a decrease in cannabinoid receptor binding and mRNA levels in the caudate-putamen, where cell bodies of cannabinoid receptor-containing neurons in the basal ganglia are located. However, this decrease particularly affected the receptor binding levels in those neurons projecting to the entopeduncular nucleus, but not in those projecting to the globus pallidus and substantia nigra, although, in this last region, a specific decrease in the efficiency of receptor activation of signal transduction mechanisms was seen in delta 9-THC-tolerant rats. The chronic exposure to delta 9-THC also resulted in decreased cannabinoid receptor binding in the cerebellum, although without affecting mRNA expression.

Analgesics↗

PubMed1997

Atypical location of cannabinoid receptors in white matter areas during rat brain development.

Previous evidence suggests that the endogenous cannabinoid system could emerge and be operative early during brain development. In the present study, we have explored the distribution of specific binding for cannabinoid receptors in rat brain at gestational day 21 (GD21), postnatal days 5 (PND5) and 30 (PND30), and at adult age (> 70 days after birth) by using autoradiography with [3H]CP-55,940. Our results indicated that specific binding for cannabinoid receptors can be detected in the brain of rat fetuses at GD21 in the classic areas that contain these receptors in adulthood-in particular, in the cerebellum and the hippocampus and, to a lesser extent, in the basal ganglia, several limbic structures, and cerebral cortex. The density of cannabinoid receptors in all these structures increased progressively at all postnatal ages studied until reaching the classical adult values in 70-day-old animals. Interestingly, cannabinoid receptor binding can also be detected at GD21 in regions, in which they are scarcely distributed or not located in the adult brain and that have the particularity of all being enriched in neuronal fibers. Among these were the corpus callosum, anterior commissure, stria terminalis, fornix, white matter areas of brainstem, and others. This atypical location was quantitatively high at GD21, tended to wane at PND5, and practically disappeared at PND30 and in adulthood, with the only exception being the anterior commissure, which exhibited a moderate density for cannabinoid receptors. Moreover, the binding of [3H]CP-55,940 to cannabinoid receptors in the white matter regions at GD21 seems to be functional and involves a GTP-binding protein-mediated mechanism. Thus, the activation of these receptors with an agonist such as WIN-55,212-2 increased the binding of [35S]-guanylyl-5'-O-(gamma-thio)-triphosphate, measured by autoradiography, in the corpus callosum and white matter areas of brainstem of fetuses at GD21. This increase was reversed by coincubation of WIN-55,212-2 with SR141716, a cannabinoid receptor antagonist. As this antagonist is specific for the cerebral cannabinoid receptor subtype, called CB1, we can assert that the signal found for cannabinoid receptor binding in the fetal and early postnatal brain likely corresponds to this receptor subtype. Collectively, all these data suggest the existence of a transient period of the brain development in the rat, around the last days of the fetal period and the first days of postnatal life, in which CB1 receptors appear located in neuronal fiber-enriched areas. During this period, CB1 receptors would be already functional acting through a GTP-binding protein-mediated mechanism. After this transient period, they progressively acquire the pattern of adult distribution. All this accounts for a specific role of the endogenous cannabinoid system in brain development.

Animals↗

PubMed1997

delta 9-Tetrahydrocannabinol increases activity of tyrosine hydroxylase in cultured fetal mesencephalic neurons.

The exposure of pregnant rats to delta 9-tetrahydrocannabinol (delta 9-THC), the main psychoactive constituent of Cannabis sativa, during gestation and lactation, affects the gene expression and the activity of tyrosine hydroxylase (TH) in the brain of their offspring, measured at fetal and early postnatal ages, when the expression of this enzyme plays an important role in neural development. In the present article, we have examined whether delta 9-THC is able to affect TH activity in cultured mesencephalic neurons obtained from fetuses at gestational d 14. Thus, TH activity increased approximately twofold in cells obtained from naive fetuses when exposed for 24 h to medium containing delta 9-THC. In addition, TH activity was also approx twofold higher in cells obtained from fetuses exposed daily to delta 9-THC from d 5 of gestation than in cells obtained from control fetuses, when both were exposed to basal media. This effect of delta 9-THC on TH activity seems to be produced via the activation to cannabinoid receptors, in particular the CB1 subtype, which would presumably be located in these cells. This is because the exposure to medium containing both delta 9-THC and SR141716A, a specific antagonist for CB1 receptors, abolished the effect observed with delta 9-THC alone. SR141716A alone was without effect on TH activity. Collectively, our results support the notion that delta 9-THC increased TH activity in cultured mesencephalic neurons, as previously observed in vivo, and that this effect was produced by activation of CB1 receptors, which seem to be operative at these early ages. All this points to a role for the endogenous cannabimimetic system in brain development.

Animals↗