The aim of the present study was to examine the role of 5-HT3 receptors in spontaneous and K+-evo... more The aim of the present study was to examine the role of 5-HT3 receptors in spontaneous and K+-evoked acetylcholine (ACh) release from rat entorhinal cortex and striatal slices. The 5-HT3 receptor antagonists ondansetron and granisetron (0.01–10 μM) produced a concentration-dependent increase in both spontaneous and K+-evoked [3H]ACh release in the two brain regions studied. The release of ACh was Ca2+-dependent and tetrodotoxin-sensitive. 5-HT3 receptor agonists, such as 2-methyl-5-HT and 1-phenylbiguanide, at concentrations up to 1 μM, did not show any intrinsic effect on [3H]ACh release in both rat brain regions. However, 2-methyl-5-HT, 1 μM, fully blocked the ondansetron-induced enhancement in both basal and K+-evoked ACh release, suggesting that 5-HT3 through 5-HT3 receptor activation, tonically inhibits ACh release. The possible implication of interposed inhibitory systems in ACh release after 5-HT3 receptor blockade was subsequently analyzed. While the effect of ondansetron was not modified by haloperidol or naloxone, the GABAA receptor antagonist bicuculline produced a marked potentiation of ACh release in the entorhinal cortex but not in the striatum. The results suggest that in this cortical area 5-HT activates 5-HT3 receptors located on GABAergic neurons which in turn inhibit cholinergic function.
Neuropsychiatric symptoms seen in Alzheimer’s disease (AD) are not simply a consequence of neurod... more Neuropsychiatric symptoms seen in Alzheimer’s disease (AD) are not simply a consequence of neurodegeneration, but probably result from differential neurotransmitter alterations, which some patients are more at risk of than others. Therefore, the hypothesis of this study is that an imbalance between the cholinergic and serotonergic systems is related to cognitive symptoms and psychological syndromes of dementia (BPSD) in patients with AD. Cholinergic and serotonergic functions were assessed in post-mortem frontal and temporal cortex from 22 AD patients who had been prospectively assessed with the Mini-Mental State examination (MMSE) for cognitive impairment and with the Present Behavioral Examination (PBE) for BPSD including aggressive behavior, overactivity, depression and psychosis. Not only cholinergic deficits, but also the cholinacetyltransferase/serotonin ratio significantly correlated with final MMSE score both in frontal and temporal cortex. In addition, decreases in cholinergic function correlated with the aggressive behavior factor, supporting a dual role for the cholinergic system in cognitive and non-cognitive disturbances associated to AD. The serotonergic system showed a significant correlation with overactivity and psychosis. The ratio of serotonin to acetylcholinesterase levels was also correlated with the psychotic factor at least in women. It is concluded that an imbalance between cholinergic–serotonergic systems may be responsible for the cognitive impairment associated to AD. Moreover, the major findings of this study are the relationships between neurochemical markers of both cholinergic and serotonergic systems and non-cognitive behavioral disturbances in patients with dementia.
Between 2003 and 2008, the marketing and distributing company DMG challenged the core financial o... more Between 2003 and 2008, the marketing and distributing company DMG challenged the core financial order in Colombia and highlighted the emergence of an economic alternative in a marginal region of the country. This model, which shared some of the characteristics of a classic pyramid scheme, was assembled as an amalgam of legal and illegal economic activities in a space dominated by the illicit drug economy. I argue that the inhabitants of Putumayo, tired of demanding full inclusion in the nation-state and moved by feelings of abandonment and resentment of drug policies that criminalized them and the activities necessary to their economic survival, legitimized and even identified with the activities of DMG, which offered them access to well-being that the state denied them,
The aim of the present study was to examine the role of 5-HT3 receptors in spontaneous and K+-evo... more The aim of the present study was to examine the role of 5-HT3 receptors in spontaneous and K+-evoked acetylcholine (ACh) release from rat entorhinal cortex and striatal slices. The 5-HT3 receptor antagonists ondansetron and granisetron (0.01–10 μM) produced a concentration-dependent increase in both spontaneous and K+-evoked [3H]ACh release in the two brain regions studied. The release of ACh was Ca2+-dependent and tetrodotoxin-sensitive. 5-HT3 receptor agonists, such as 2-methyl-5-HT and 1-phenylbiguanide, at concentrations up to 1 μM, did not show any intrinsic effect on [3H]ACh release in both rat brain regions. However, 2-methyl-5-HT, 1 μM, fully blocked the ondansetron-induced enhancement in both basal and K+-evoked ACh release, suggesting that 5-HT3 through 5-HT3 receptor activation, tonically inhibits ACh release. The possible implication of interposed inhibitory systems in ACh release after 5-HT3 receptor blockade was subsequently analyzed. While the effect of ondansetron was not modified by haloperidol or naloxone, the GABAA receptor antagonist bicuculline produced a marked potentiation of ACh release in the entorhinal cortex but not in the striatum. The results suggest that in this cortical area 5-HT activates 5-HT3 receptors located on GABAergic neurons which in turn inhibit cholinergic function.
Neuropsychiatric symptoms seen in Alzheimer’s disease (AD) are not simply a consequence of neurod... more Neuropsychiatric symptoms seen in Alzheimer’s disease (AD) are not simply a consequence of neurodegeneration, but probably result from differential neurotransmitter alterations, which some patients are more at risk of than others. Therefore, the hypothesis of this study is that an imbalance between the cholinergic and serotonergic systems is related to cognitive symptoms and psychological syndromes of dementia (BPSD) in patients with AD. Cholinergic and serotonergic functions were assessed in post-mortem frontal and temporal cortex from 22 AD patients who had been prospectively assessed with the Mini-Mental State examination (MMSE) for cognitive impairment and with the Present Behavioral Examination (PBE) for BPSD including aggressive behavior, overactivity, depression and psychosis. Not only cholinergic deficits, but also the cholinacetyltransferase/serotonin ratio significantly correlated with final MMSE score both in frontal and temporal cortex. In addition, decreases in cholinergic function correlated with the aggressive behavior factor, supporting a dual role for the cholinergic system in cognitive and non-cognitive disturbances associated to AD. The serotonergic system showed a significant correlation with overactivity and psychosis. The ratio of serotonin to acetylcholinesterase levels was also correlated with the psychotic factor at least in women. It is concluded that an imbalance between cholinergic–serotonergic systems may be responsible for the cognitive impairment associated to AD. Moreover, the major findings of this study are the relationships between neurochemical markers of both cholinergic and serotonergic systems and non-cognitive behavioral disturbances in patients with dementia.
Between 2003 and 2008, the marketing and distributing company DMG challenged the core financial o... more Between 2003 and 2008, the marketing and distributing company DMG challenged the core financial order in Colombia and highlighted the emergence of an economic alternative in a marginal region of the country. This model, which shared some of the characteristics of a classic pyramid scheme, was assembled as an amalgam of legal and illegal economic activities in a space dominated by the illicit drug economy. I argue that the inhabitants of Putumayo, tired of demanding full inclusion in the nation-state and moved by feelings of abandonment and resentment of drug policies that criminalized them and the activities necessary to their economic survival, legitimized and even identified with the activities of DMG, which offered them access to well-being that the state denied them,
Uploads
Papers by maria ramirez