Nicotinamide, an acetylcholinesterase uncompetitive inhibitor, protects the blood‒brain barrier and improves cognitive function in rats fed a hypercaloric diet.

Oxidative stress and inflammation induced by abundant consumption of high-energy foods and caloric overload are implicated in the dysfunction of the blood‒brain barrier (BBB), cognitive impairment, and overactivation of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). These enzymes hydrolyse acetylcholine, affecting anti-inflammatory cholinergic signalling. Our aim was to evaluate whether nicotinamide (NAM) attenuates the impairment of the BBB and cognitive function, improving cholinergic signalling. Forty male rats were distributed into five groups: one group was fed a standard diet, and the remaining groups were fed a high-fat diet and a beverage with 40% sucrose (HFS; high-fat sucrose). In three of the HFS groups, the carbohydrate was replaced by drinking water containing different concentrations of NAM for 5 h every morning for 12 weeks. The biochemical profile, levels of stress and inflammation markers, cholinesterase activities, BBB permeability, and cognitive capacity were evaluated. The results showed that the HFS diet disturbed the metabolism of carbohydrates and lipids, causing insulin resistance. Simultaneously, AChE and BChE activities, levels of proinflammatory cytokines, oxidation of proteins and lipoperoxidation increased along with decreased antioxidant capacity in serum. In the hippocampus, increased activity of cholinesterases, protein carbonylation and lipoperoxidation were associated with decreased antioxidant capacity. Systemic and hippocampal changes were reflected in increased BBB permeability and cognitive impairment. In contrast, NAM attenuated the above changes by reducing oxidative stress and inflammation through decreasing cholinesterase activities, especially by uncompetitive inhibition. NAM may be a potential systemic and neuroprotective agent to mitigate cognitive damage due to hypercaloric diets.

Women and COVID-19: severity and mortality in hospitalized middle-aged and older patients.

OBJECTIVE: The aim of the study was to evaluate the clinical features, severity, and mortality of coronavirus disease-2019 (COVID-19) in hospitalized middle-aged and older women, and the risk factors associated with severity and mortality in women. METHODS: A retrospective study was conducted in hospitalized patients with COVID-19. The clinical features, severity, and mortality of COVID-19 in middle-aged and older women (age 45 years and older) were compared to those of younger women (age <45 years). RESULTS: A higher frequency of hypertension, invasive mechanical ventilation (IMV) requirement, and mortality was evidenced in middle-aged and older women. Age ≥45 years (odds ratio 2.7; 95% confidence interval 1.21-6.27; p = 0.01) and IMV requirement (odds ratio 3.0; 95% confidence interval 1.34-6.76; p = 0.004) predicted mortality. CONCLUSIONS: Severity and mortality are higher in middle-aged and older women with COVID-19 compared to younger women.

Nicotinamide reduces inflammation and oxidative stress via the cholinergic system in fructose-induced metabolic syndrome in rats.

AIMS: Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) have been associated with risk factors for metabolic syndrome (MetS). Our objective was to evaluate the effect of nicotinamide (NAM) on the activities, expression and protein content of cholinesterases in a MetS model. MAIN METHODS: MetS was induced in male rats administrating 40% fructose to the drinking water for 16 weeks. Additionally, from 5th week onward, the carbohydrate solution was replaced by NAM, at several concentrations for 5 h each morning for the next 12 weeks. In the 15th week, the glucose tolerance test was conducted, and blood pressure was measured. After the treatment period had concluded, the biochemical profile; oxidant stress; proinflammatory markers; and the activity, quantity and expression of cholinesterases were evaluated, and molecular docking analysis was performed. KEY FINDINGS: The MetS group showed anthropometric, hemodynamic and biochemical alterations and increased cholinesterase activity, inflammation and stress markers. In the liver, cholinesterase activity and mRNA, free fatty acid, tumor necrosis factor-alpha (TNF-α), and thiobarbituric acid-reactive substance (TBARS) levels were increased, while reduced glutathione (GSH) levels were decreased. NAM partially or totally decreased risk factors for MetS, markers of stress and inflammation, and the activity (serum and liver) and expression (liver) of cholinesterases. Molecular docking analysis showed that NAM has a greater affinity for cholinesterases than acetylcholine (ACh), suggesting NAM as an inhibitor of cholinesterases. SIGNIFICANCE: Supplementation with 40% fructose induced MetS, which increased the activity and expression of cholinesterases, oxidative stress and the inflammation. NAM attenuated these MetS-induced alterations and changes in cholinesterases.

High fructose-containing drinking water-induced steatohepatitis in rats is prevented by the nicotinamide-mediated modulation of redox homeostasis and NADPH-producing enzymes.

An imbalance in the redox state, increased levels of lipid precursors and overactivation of de novo lipogenesis determine the development of fibrosis during nonalcoholic steatohepatitis (NASH). We evaluated the modulation of NADPH-producing enzymes associated with the antifibrotic, antioxidant and antilipemic effects of nicotinamide (NAM) in a model of NASH induced by excess fructose consumption. Male rats were provided drinking water containing 40% fructose for 16 weeks. During the last 12 weeks of fructose administration, water containing NAM was provided to some of the rats for 5 h/day. The biochemical profiles and the ghrelin, leptin, lipoperoxidation and TNF-α levels in serum and the glucose-6-phosphate dehydrogenase (G6PD), malic enzyme (ME) and NADP+-dependent isocitric dehydrogenase (IDP) levels, the reduced/oxidized glutathione (GSH/GSSG) and reduced/oxidized nicotinamide adenine dinucleotide (phosphate) (NAD(P)H/NAD(P)+) ratios, and the levels of various lipogenic and fibrotic markers in the liver were evaluated. The results showed that hepatic fibrosis induced by fructose consumption was associated with weight gain, hunger-satiety system dysregulation, hyperinsulinemia, dyslipidemia, lipoperoxidation and inflammation. Moreover, increased levels of hepatic G6PD and ME activity and expression, the NAD(P)H/NAD(P)+ ratios, and GSSG concentration and increased expression of lipogenic and fibrotic markers were detected, and these alterations were attenuated by NAM administration. Specifically, NAM diminished the activity and expression of G6PD and ME, and this effect was associated with a decrease in the NADPH/NADP+ ratios, increased GSH levels and decreased lipoperoxidation and inflammation, ameliorating fibrosis and NASH development. NAM reduces liver steatosis and fibrosis by regulating redox homeostasis through a G6PD- and ME-dependent mechanism.

Memory consolidation and amnesia modify 5-HT6 receptors expression in rat brain: an autoradiographic study.

Traditionally, the search for memory circuits has been centered on examinations of amnesic and AD patients, cerebral lesions and, neuroimaging. A complementary alternative might be the use of autoradiography with radioligands. Indeed, ex vivo autoradiographic studies offer the advantage to detect functionally active receptors altered by pharmacological tools and memory formation. Hence, herein the 5-HT(6) receptor antagonist SB-399885 and the amnesic drugs scopolamine or dizocilpine were used to manipulate memory consolidation and 5-HT(6) receptors expression was determined by using [(3)H]-SB-258585. Thus, memory consolidation was impaired in scopolamine and dizocilpine treated groups relative to control vehicle but improved it in SB-399885-treated animals. SB-399885 improved memory consolidation seems to be associated with decreased 5-HT(6) receptors expression in 15 out 17 brain areas. Scopolamine or dizocilpine decreased 5-HT(6) receptors expression in nine different brain areas and increased it in CA3 hippocampus or other eight areas, respectively. In brain areas thought to be in charge of procedural memory such basal ganglia (i.e., nucleus accumbens, caudate putamen, and fundus striate) data showed that relative to control animals amnesic groups showed diminished (scopolamine) or augmented (dizocilpine) 5-HT(6) receptor expression. SB-399885 showing improved memory displayed an intermediate expression in these same brain regions. A similar intermediate expression occurs with regard to amygdala, septum, and some cortical areas in charge of explicit memory storage. However, relative to control group amnesic and SB-399885 rats in the hippocampus, region where explicit memory is formed, showed a complex 5-HT(6) receptors expression. In conclusion, these results indicate neural circuits underlying the effects of 5-HT(6) receptor antagonists in autoshaping task and offer some general clues about cognitive processes in general.

Modifications of 5-HT4 receptor expression in rat brain during memory consolidation.

Pharmacological evidence indicates a specific role of 5-HT(4) receptors on memory function. These receptors are members of G-protein-coupled 7-transmembrane domain receptor superfamily, are positively coupled to adenylyl cyclase, and are heterogeneously located in some structures important for memory, such as the hippocampus and cortical regions. To further clarify 5-HT(4) receptors' role in memory, the expression of these receptors in passive (P3) untrained and autoshaping (A3) trained (3 sessions) adult (3 months) and old (P9 or A9; 9 months) male rats was determined by autoradiography. Adult trained (A3) rats showed a better memory respect to old trained (A9). Using [(3)H] GR113808 as ligand (0.2 nM specific activity 81 Ci/mmol) for 5-HT(4) receptor expression, 29 brain areas were analyzed, 16 areas of A3 and 17 of A9 animals displayed significant changes. The medial mammillary nucleus of A3 group showed diminished 5-HT(4) receptor expression, and in other 15 brain areas of A3 or 10 of A9 animals, 5-HT(4) receptors were increased. Thus, for A3 rats, 5-HT(4) receptors were augmented in olfactory lobule, caudate putamen, fundus striatum, CA2, retrosplenial, frontal, temporal, occipital, and cingulate cortex. Also, 5-HT(4) receptors were increased in olfactory tubercule, hippocampal CA1, parietal, piriform, and cingulate cortex of A9. However, hippocampal CA2 and CA3 areas, and frontal, parietal, and temporal cortex of A9 rats, expressed less 5-HT(4) receptors. These findings suggest that serotonergic activity, via 5-HT(4) receptors in hippocampal, striatum, and cortical areas, mediates memory function and provides further evidence for a complex and regionally specific regulation over 5-HT receptor expression during memory formation.

5-HT1A receptor expression during memory formation.

RATIONALE: It has been reported that 5-HT(1A) receptors modulate learning and memory and diverse pharmacological and genetic evidence supports this notion. Nevertheless, there are few works about expression of these receptors during memory formation. OBJECTIVE: We aimed to determine 5-HT(1A) receptor expression in brain areas of untrained, passive, and autoshaping trained groups of rats. METHODS: Ex vivo receptor autoradiography using the ligand agonist [(3)H]8-hydroxy-2-[di-n-propylamino]tetralin] (8-OH-DPAT) was used. RESULTS: The trained group relative to untrained animals showed increases of 5-HT(1A) receptor expression in 14 brain areas, decrements in 7, and no changes in 12. Thus, in contrast to untrained rats, 5-HT(1A) receptor expression of autoshaping trained rats was augmented in the tubercule olfactory, septal nucleus, nucleus accumbens, caudate putamen, globus pallidus, striate, and parietal (1 and 2), temporal cortex (1 and 3), granular retrosplenial cortex (1), amygdala, and median and dorsal raphe nuclei. In contrast, in the latter group, receptors were decreased in the CA1 area, hypothalamus dorsal, frontal cortex (1 and 3), occipital cortex, cingulate cortex (1 and 2), and cuneiform nucleus. There were significant differences between passive vs trained groups, but not regarding untrained rats, in the lateral olfactory tract, dentate gyrus, CA3 area, ventromedial hypothalamic, lateral hypothalamus, preoptic medial, frontal cortex (2), granular retrosplenial cortex (2), entorhinal cortex (1 and 2), piriform cortex, and substantia nigra. CONCLUSIONS: These data suggest that upregulated, downregulated, and "silence" of 5-HT(1A) receptors in brain areas form part of neural circuits engaged in memory formation by demonstrating a high degree of specificity and memory mapping.

Expression of the 5-HT receptors in rat brain during memory consolidation.

Serotonin (5-hydroxytryptamine, 5-HT) system displays more than 14 receptors subtypes on brain areas involved in learning and memory processes, and pharmacological manipulation of specific receptors selectively affects memory formation. In order to begin the search of 5-HT receptors expression during memory formation, in this work, we aimed to determine, by autoradiography (using 3H 5-HT as ligand, 2 nM, specific activity 123 Ci/mmol), 5-HT receptors (5-HTR) expression in passive (untrained) and autoshaping trained (3 sessions) adult (3 months) and old (9 months) male rats. Thus, trained adult rats had better retention than old animals. Raphe nuclei of adult and old trained rats expressed less receptors on medial and dorsal, respectively. Hippocampal CA1 area and dentate gyrus of adult trained rats expressed less 5-HTR, while dentate gyrus of old increased them. Basomedial amygdaloid nucleus in old trained rats expressed more 5-HTR; while in the basolateral amygdaloid nucleus they were augmented in both groups. Training decreased or did not change 5-HTR in caudate-putamen of adult or old animals. The above profile of 5-HTR expression is consistent with previous reports, and suggests that memory formation and aging modulates 5-HTR expression in brain areas relevant to memory systems.

8-OH-DPAT facilitated memory consolidation and increased hippocampal and cortical cAMP production.

Animals were submitted to an associative learning task named Pavlovian/instrumental autoshaping (P/I-A) and treated with selective 5-HT1A and 5-HT7 receptor agonists and antagonists. Next, they were sacrificed, their brains removed, dissected and changes on cortical and hippocampal cyclic adenosine monophosphate (cAMP) production were determined. Results revealed that, the 8-OH-DPAT treatment facilitated memory consolidation of autoshaping and that effect was blocked completely by WAY100635 and partially by DR4004. WAY100635 or DR4004 alone had no effect on autoshaping. The cAMP results were complex and yielded no clear relationship to the memory results. Thus, cortical and hippocampal increased on cAMP production was observed following administration of the 5-HT(1A/7) agonist 8-OH-DPAT. The memory effect was, completely or partially, reversed by the selective antagonists WAY100635 (5-HT1A) or DR4004 (5-HT7), respectively.

Frequency of macroprolactinemia due to autoantibodies against prolactin in pregnant women.

The frequency of macroprolactinemia related to the presence of anti-PRL autoantibodies in the serum of 209 healthy women at different stages of pregnancy was studied. Measurements were taken of serum PRL concentrations before and after chromatographic separation (gel filtration and affinity with proteins A and G) and extraction of free PRL with polyethylene glycol (PEG). Sera from 8 of the 209 women (3.8%) were found to have a significantly high proportion of precipitated PRL by PEG (macroprolactinemia); in these patients, gel filtration showed that a substantial amount of big big PRL (molecular mass >100 kDa) was present (19.0--78.2% vs. 3.8-4.9%, P = 0.009 in normal pregnant women with a normal proportion of precipitated PRL by PEG). The presence of macroprolactinemia was attributable to anti-PRL autoantibodies in 5 of the 8 women. Comparison of serum levels of direct and free PRL between women with macroprolactinemia related to anti-PRL autoantibodies and women without macroprolactinemia showed significant differences (direct PRL: 270.2 +/- 86.9 vs. 203.4 +/- 69.0 microg/L, P = 0.04; and free PRL: 107.0 +/- 75.9 vs. 173.3 +/- 67.6 microg/L, P = 0.002). On the other hand, there was no difference between women with macroprolactinemia not related to anti-PRL autoantibodies and women with macroprolactinemia caused by anti-PRL autoantibodies, nor was there a difference between women with macroprolactinemia not related to anti-PRL autoantibodies and women without macroprolactinemia. There was a positive correlation between titers of the anti-PRL autoantibody and serum PRL levels (r = 0.82, P = 0.09). The presence of the anti-PRL autoantibody had no relation to the patient's age, stage of gestation, or number of previous pregnancies. We concluded that the frequency of macroprolactinemia was 3.8% among healthy, pregnant women, which was caused by a anti-PRL autoantibodies in 62.5% of the cases. The autoantibodies were found in the bloodstream, forming a PRL-IgG complex, in accordance with the following observations: 1) immunoreactive PRL on gel filtration was eluted in the fractions corresponding to the molecular mass of IgG (150 kDa); 2) a significantly high proportion of immunoreactive PRL was retained on an affinity gel for IgG (proteins A and G); and 3) a significantly high proportion of serum PRL bound to IgG was precipitated by protein A. There was a positive correlation between titers of anti-PRL autoantibodies and serum PRL levels. Serum levels of total PRL were higher, and serum levels of free PRL were lower, in pregnant women with anti-PRL autoantibodies than in pregnant women without macroprolactinemia.