Table 2B.
Methodological quality of preclinical studies investigating palmitoylethanolamide and its correlations to neurocognitive disorders (NCDs).
| References | Study design | Defined study population | Age | Gender | PEA measure | Adequate PEA evaluation | Control | Comparability of subjects | Statistical analyses | Funding or sponsorship |
|---|---|---|---|---|---|---|---|---|---|---|
| Scuderi et al. (29) (Italy) | √ Analytic, observational, interventional | √ Astrocytes from newborn Sprague-Dawley rats | √ PND 2 | X | √ PEA 10−7 M (in vitro addition) | √ 24-hour application (added to medium after Aβ administration) | √ CTRL; Aβ | √ Study population; experimental conditions | √ ANOVA, Bonferroni's test, Newman-Keuls test | X |
| Benito et al. (30) (Italy) | √ Analytic, observational, interventional | √ Astrocites from newborn FAAH-KO mice; Astrocites from newborn C57/BL6 mice | √ PND 1 | X | √ PEA 10 μM (in vitro addition) | √ 24-hour alone or combined application (added to medium prior to Aβ administration) | √ CTRL-WT; Aβ-WT | √ Study population; experimental conditions | √ ANOVA, Student's t-test, Newman-Keuls test | X |
| D'Agostino et al. (31) (Italy) | √ Analytic, observational, interventional | √ WT mice; PPAR-α -/- mice backcrossed to C57/BL6 | X | √ Male | √ 1. First set of mice: PEA 3 mg/Kg, 10 mg/Kg, 30 mg/kg (sc administration); 2. Second and 3. Third sets of mice: 30 mg/Kg (sc administration) |
√ 1. First and 3. Third sets of mice: daily administration (7 days and 5 days); 2. Second set of mice: single administration (30 min before test) |
√ ScAb+VHI; Ab+VHI; Ab+GW7647 | √ Study population; experimental conditions; gender | √ ANOVA, Student's t-test, Dunnett's post hoc test, Wilcoxon signed-rank test | √ |
| Scuderi et al. (32) (Italy) | √ Analytic, observational, interventional | √ Sprague-Dawley rats | √ 1. Primary cultures of cerebral cortex neurons: ED 18; 2. Primary cultures of cerebral cortex astrocytes: PND 1-2 |
X | √ PEA 0.1 μM (in vitro addition) | √ Alone or combined application (added to medium after Aβ administration) | √ CTRL; Aβ | √ Study population; experimental conditions | √ ANOVA, Bonferroni's test | √ |
| Scuderi and Steardo (33) (Italy) | √ Analytic, observational, interventional | √ Sprague-Dawley rats | √/X Primary cultures of cerebral cortex neurons: ED 18 | X | √ PEA 0.1 μM (ex vivo/in vivo addition) | √ 24-h alone or combined application (added to medium after Aβ administration) | √ CTRL; Aβ | √ Study population; experimental conditions | √ ANOVA, Bonferroni's test | √ |
| Paterniti et al. (22) (Italy) | √ Analytic, observational, interventional | √ CD1 mice | √ PND 6 | X | √ co-ultra PEALut (um-PEA 0.27 μM + luteolin 0.027 μM or um-PEA 2.7 μM + luteolin 0.27 μM or um-PEA 27 μM + luteolin 2.7 μM) addition to medium | √ Single application (added to medium after 21-day incubation, 2 h before Aβ) | √ CTRL; Aβ | √ Study population; age; experimental conditions | √ ANOVA, Bonferroni's test | X |
| Scuderi et al. (34) (Italy) | √ Analytic, observational, interventional | √ Sprague-Dawley rats | √/X Adult | √ Male | √ PEA 10 mg/Kg (ip administration) | √ Daily administration (7 days) | √ VHI; VHI+Aβ | √ Study population; experimental conditions; gender; age | √ ANOVA, Bonferroni's test | √ |
| Cipriano et al. (25) (Italy) | √ Analytic, observational, interventional | √ C6 rat glioma cells | X | X | √ PEA 10∧−6, 10∧−7, 10∧−8 M (in vitro addition) | √ 48-h alone or combined application (added to medium after Aβ administration) | √ CTRL; Aβ; Aβ+PEA10∧−6+GW6471 | √ Study population; experimental conditions | √ ANOVA, Bonferroni's test | X |
| Tomasini et al. (35) (Italy) | √ Analytic, observational, interventional | √ 3 × Tg-AD mice; non-Tg mice | X | X | √ PEA 0.1 μM (in vitro addition) | √ 24-h application (added to medium 1 h before Aβ administration) | √ (3xTg-AD, non-Tg): CTRL; Aβ | √ Study population; experimental conditions | √ ANOVA, Newman-Keuls test | √ |
| Caltagirone et al. (24) (Italy) | √ Analytic, observational, interventional | √ Wistar rats | X | √ Male | √ co-ultraPEALut 1 mg/Kg (oral administration) | √ Double administration (1 h after ischemia, 6 h after reperfusion) | √ MCAo+VHI; sham+VHI | √ Study population; experimental conditions; gender | √ ANOVA, Student's t-test, Bonferroni's test, Newman-Keuls test | √ |
| Siracusa et al. (36) (Italy) | √ Analytic, observational, interventional | √ CD1 mice; Sprague-Dawley rats | X | √ Male | √ 1. Brain tissue levels (healthy rats); 2. co-ultra PEALut 1 mg/Kg (oral administration) (mice) |
√ 1. Single assessment (healthy rats); 2. Daily administration (15 days, 24 h after VaD induction) (mice) |
√ sham+VHI; sham+PEA; VaD+VHI | √ Study population; gender; experimental conditions | √ ANOVA, Bonferroni's test | X |
| Beggiato et al. (37) (Italy) | √ Analytic, observational, interventional | √ Cerebral cortex astrocytes from C57/BL6 mice; Cerebral cortex neurons from C57/BL6 mice | √ 1. Primary cultures of cerebral cortex neurons: ED 18; 2. Primary cultures of cerebral cortex astrocytes: PND 1-2 | X | √ PEA 0.1 μM (in vitro addition) | √ 24-h alone or combined application (added to medium 1 h before Aβ administration) | √ CTRL; Aβ | √ Study population; experimental conditions | √ ANOVA, Newman-Keuls test | √ |
| Bronzuoli et al. (20) (Italy) | √ Analytic, observational, interventional | √ 1. 3 × Tg-AD mice; 2. non-Tg mice | √ 1. In vivo: 3 months; 2. In vitro: PND 1-2 |
√ Male | √ 1. um-PEA 10 mg/kg (sc administration); 2. PEA 0.01, 0.1, 1 μM (in vitro addition) |
√ 1. Daily administration (90 days); 2. 24-h application (added to medium after 7 and 28 days, for astrocytes and neurons respectively) |
√ (3xTg-AD, non-Tg): CTRL | √ Study population; experimental conditions; gender; age | √ ANOVA, Student's t-test, Bonferroni's test | X |
| Crupi et al. (39) (Italy) | √ Analytic, observational, interventional | √ CD1 mice | √ 21 months | √ Male | √ PEAm 10 mg/Kg (oral administration) | √ Daily administration (60 days) | √ sham+VHI; sham+PEA; MPTP+VHI | √ Study population; age; gender; experimental conditions | √ ANOVA, Bonferroni's test | X |
| Scuderi et al. (20) (Italy) | √ Analytic, observational, interventional | √ 3 × Tg-AD mice | √ 1. First set of mice: 3 to 6 months; 2. Second set of mice: 9 to 12 months |
√ Male | √ um-PEA 28 mg (sc administration) | √ Daily administration (3 months) | √ non-Tg mice; placebo | √ Study population; age; gender; experimental conditions | √ ANOVA, Tukey's HSD test, Bonferroni's test | √ |
| Boccella et al. (40) (Italy) | √ Analytic, observational, interventional | √ C57/BL6 mice | X | √ Male | √ um-PEA 10 mg/Kg (ip administration) | √ Daily administration (15 days, starting 15 days after sham or SNI) | √ sham groups; SNI+VHI; SNI+MPEP; SNI+MPEP+PEA; SNI+MDCPG; SNI+MDCPG+PEA | √ Study population; gender; experimental conditions | √ ANOVA, Dunnett's multiple comparison post hoc test, Student's t-test, Bonferroni's test | √ |
| Boccella et al. (41) (Italy) | √ Analytic, observational, interventional | √ WT mice; PPAR-α -/- mice backcrossed to C57/BL6 | X | √ Male | √ 1. um-PEA 10 mg/Kg (ip administration); 2. Brain tissue levels |
√ 1. Daily administration (15 days, starting 15 days after sham or SNI); 2. Single assessment |
√ sham+VHI; sham+PEA; SNI+VHI | √ Study population; gender; experimental conditions | √ ANOVA, Dunnett's multiple comparison post hoc test, Student's t-test, D'Agostino-Pearson's normality test, Bonferroni's test, Kruskall-Wallis test, Dunn's test | √ |
| Impellizzeri et al. (42) (Italy) | √ Analytic, observational, interventional | √ CD1 mice | X | √ Male | √ 1. PEA-OXA 10 mg/kg (oral administration); 2. Brain tissue levels |
√ 1. Daily administration (15 days); 2. Single assessment |
√ sham+VHI; sham+PEA; VaD+VHI | √ Study population; gender; experimental conditions | √ ANOVA, Bonferroni's test, Neuman-Keuls multiple comparison test | X |
| Piscitelli et al. (43) (Italy) | √ Analytic, observational | √ Tg2576 mice | √ 4–15 months | √ Male | √ 1. Plasma levels; 2. Brain tissue levels |
√ Multiple assessment (T1 presymptomatic: 4–6 months; T2 mild symptomatic: 7–10 months; T3 symptomatic: 12–15 months) | √ WT | √ Age; experimental conditions | √ ANOVA, Tukey's post hoc test, Tukey HSD test | √ |
| Zimmermann et al. (44) (Germany) | √ Analytic, observational | √ NEX-Cre mice (C57/BL6 background) | √ 2–3 months | √ Male | √ Brain tissue levels | √ Single assessment | √ AAV-WT; AAV-Glu-empty | √ Age; gender; experimental condition | √ ANOVA, Tukey's post hoc test, Student's t-test, Kolmogorov-Smirnov test, Bonferroni's test, Sidak's multiple comparison test | √ |
| Beggiato et al. (45) (Italy) | √ Analytic, observational, interventional | √ 3 × Tg-AD mice | √ 1. Primary cultures of cerebral cortex neurons: ED 18; 2. Primary cultures of cerebral cortex astrocytes: PND 1-2 |
X | √ PEA 0.1 μM (in vitro addition) | √ 24-h application (added to medium 1 h before Aβ) | √ non-Tg mice; 3xTg-AD(CTRL); 3xTg-AD(Aβ) | √ Study population; experimental conditions | √ Student's t-test | √ |
| Beggiato et al. (46) (Italy) | √ Analytic, observational, interventional | √ 3 × Tg-AD mice; C57BL6/129SvJ mice | √ 2 months ± 2 weeks of age | √ Male | √ 1. um-PEA 100 mg/Kg (oral administration); 2. Brain tissue levels; 3. Plasma levels |
√ 1. Pharmacokinetic studies: (a) single or daily (8 days) administration; (b) single brain tissue or plasma assessment (prior to PEA; 1, 1.5, 3, 4 h after PEA); 2. Biobehavioral studies: daily administration (3 months) |
√ non-Tg; 3xTg-AD+VHI | √ Age; gender; experimental conditions | √ ANOVA, Tukey's HSD test, Bonferroni's test, Student's t-test | √ |
| Facchinetti et al. (47) (Italy) | √ Analytic, observational, interventional | √ Sprague-Dawley rats | √/X Adult rats | √ Male | √ co-ultra PEALut 5 mg/Kg (ip administration) | √ Daily administration (14 days) | √ VHI; VHI(Aβ) | √ Study population; age; gender; experimental conditions | √ ANOVA, Bonferroni's test | √ |
| Lama et al. (48) (Italy) | √ Analytic, observational, interventional | √ C57/BL6 mice | √ 6 weeks | √ Male | √ um-PEA 30 mg/Kg (oral administration) | √ Daily administration (7 weeks) | √ STD; HFD | √ Study population; age; gender; experimental conditions | √ ANOVA, Bonferroni's test | X |
| Boccella et al. (49) (Italy) | √ Analytic, observational, interventional | √ C57/BL6 mice | √ 4-5 weeks | √ Male | √ PEA-OXA 10 mg/kg (ip administration) | √ Daily administration (16 days, starting 14 days after SNI or sham surgery) | √ sham+VHI; sham+PEA; SNI+VHI | √ Study population; age; gender; experimental conditions | √ ANOVA, Kolmogorov–Smirnov test | √ |
| Campolo et al. (21) (Italy) | √ Analytic, observational, interventional | √ CD1 mice | √ 10–12 weeks | √ Male | √ co-ultra PEALut 1 mg/Kg (oral administration) | √ Daily administration (72 h and 7 days, 1 h after craniotomy) | √ sham; TBI | √ Study population; age; gender; experimental conditions | √ Student's t-test, Mann-Whitney U-test, χ2 test | X |
| D'Antongiovanni et al. (50) (Italy) | √ Analytic, observational, interventional | √ SAMP8 mice | √ 4 months | X | √ 1. PEA 5 mg/Kg (oral administration) 2. PEA 0.1 μM (in vitro addition) |
√ 1. Daily administration (2 months); 2. 1-h application (added to medium 4 h after LPS, 1 h before Aβ) |
√ SAMR1; SAMP8; CTRL; LPS+Aβ | √ Study population; age; experimental conditions | √ ANOVA, Tukey's test, Student's t-test | √ |
| Gaspar et al. (51) (Ireland) | √ Analytic, observational, interventional | √ Sprague-Dawley rats | X | √ Male | √ 1. PEA 2 mg/Kg (ip administration) 2. Brain tissue levels |
√ 1. Single administration (day 28 post-CFA); 2. Single assessment |
√ noCFA groups; CFA+VHI; CFA+GSK; CFA+GW6471; CFA+GW9662 | √ Study population; gender; experimental conditions | √ ANOVA, SNK post hoc test, Cohen's d coefficient, Kruskal Wallis test, Friedman's test, Dunn's post hoc test, Mann-Whitney U-test, Bonferroni's test, Shapiro-Wilk test, Levene's test | √ |
| Gatta et al. (52) (Italy) | √ Analytic, observational, interventional | √ 1. In vitro experiment: BV2 microglial cell model; 2. Ex vivo experiment: C57/BL6 mice |
√/X Ex vivo primary cultures of cerebral cortex microglia: PND 3 | X | √ PEA 10 μM (in vitro addition) | √ 24-/48-hour application (added to medium before or in presence of LPS or Aβ) | √ CTL; LPS+PEA; Aβ+PEA | √ Study population; experimental conditions | √ ANOVA, Tukey's test | √ |
PND, postnatal day; PEA, palmitoylethanolamide; M, molar; Aβ, β-amyloid precursor protein; CTRL, control; FAAH, Fatty acid amide hydrolase; KO, Knock-out; μM, micromolar; WT, Wild-type; PPAR, Peroxisome proliferator-activated receptor; C57/BL6, multipurpose mouse model; mg/Kg, milligrams per kilogram; sc, subcutaneous; ScAb, Scrambled Ab25-35 peptide; VHI, vehicle; Ab, Ab25-35 peptide; GW7647, PPARα agonist; ED, embryonic day; CD1, multipurpose mouse model; co-ultra PEALut, co-ultramicronized palmitoylethanolamide and luteoline; um-PEA, ultramicronized palmitoylethanolamide; ip, intraperitoneal; C6, glial cell line; GW6471, PPARα antagonist; 3xTg-AD, triple-transgenic mouse model of AD; non-Tg, non-transgenic mouse model; h, hours; MCAo, middle cerebral artery occlusion; VaD, vascular dementia; PEAm, micronized PEA; MPTP, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; HSD, honestly significant difference; SNI, spare nerve injury; MPEP, 2-Methyl-6-(phenylethynyl) pyridine; MDCPG, (RS)-4-(1-amino-1-carboxyethyl)phthalic acid; PEA-OXA, N-Palmitoylethanolamine-oxazoline; Tg2576, transgenic mouse model; T(1, 2, 3), time (1, 2, 3); NEX-Cre, mouse line expressing Cre recombinase under control of regulatory sequences of NEX; AAV, adeno-associated virus; Glu, glutamatergic neurons; 129SvJ, multipurpose mouse model; STD, standard-diet group; HFD, high-fat diet; TBI, traumatic brain injury; SAMP8, Senescence Accelerated Mouse-prone 8; SAMR1, Senescence-Accelerated Mouse-Resistant 1; LPS, lipopolysaccharide; CFA, Complete Freund's Adjuvant; GW9662, PPARγ antagonist; GSK, GSK0660 (PPARβ/δ antagonist); BV2, microglial cell line.