The toxicity of food additives is widely studied and concerns many consumers worldwide. Synthetic food colors are often considered an unnecessary risk to consumer health. Since the European Food Safety Authority’s (EFSA) re-evaluation between 2009 and 2014, the body of scientific literature on food colors has grown, and new evaluations are being published by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). Therefore, this narrative review aims to review the toxicological data that have become available since 2014. The reviewed colors are Quinoline Yellow, Sunset Yellow, Azorubine, Amaranth, Ponceau 4R, Erythrosine, Allura Red, Patent Blue, Indigo Carmine, Brilliant Blue FCF, Green S, Brilliant Black, Brown HT, and Lithol Rubine BK. Tartrazine was not included in this paper; the overwhelming amount of recent data on Tartrazine toxicity requires more space than this review can provide. The issues regarding the toxicity of synthetic food colors and real population exposures are being regularly examined and reviewed by relevant authorities, such as the EFSA and JECFA. The current ADI limits set by the authorities are mostly in agreement, and they seem safe. However, the EFSA and JECFA assessments of some of the colors are more than a decade old, and new evidence will soon be required.

Depression has been associated with drug consumption, including heavy or problematic cannabis use. According to an animal model of depression and substance use disorder comorbidity, we combined the olfactory bulbectomy model of depression with intravenous drug self-administration procedure to verify whether depressive-like rats displayed higher voluntary intake of the CB1 receptor agonist WIN55,212-2 (WIN, 12.5 µg/kg/infusion). To this aim, olfactory-bulbectomized (OBX) and sham-operated (SHAM) Lister Hooded rats were allowed to self-administer WIN by lever-pressing under a continuous (FR-1) schedule of reinforcement in 2h daily sessions. Data showed that both OBX and SHAM rats developed stable WIN intake; yet, responses in OBX were constantly higher than in SHAM rats soon after the first week of training. In addition, OBX rats took significantly longer to extinguish the drug-seeking behaviour after vehicle substitution. Acute pre-treatment with serotonin 5HT1B receptor agonist, CGS-12066B (2.5-10 mg/kg), did not significantly modify WIN intake in OBX and SHAM Lister Hooded rats. Furthermore, acute pre-treatment with CGS-12066B (10 and 15 mg/kg) did not alter responses in parallel groups of OBX and SHAM Sprague Dawley rats self-administering methamphetamine under higher (FR-2) reinforcement schedule with nose-poking as operandum. Finally, dopamine levels in the nucleus accumbens of OBX rats did not increase in response to a WIN challenge, as in SHAM rats, indicating a dopaminergic dysfunction in bulbectomized rats. Altogether, our findings suggest that a depressive state may alter cannabinoid CB1 receptor agonist-induced brain reward function and that a dopaminergic rather than a 5-HT1B mechanism is likely to underlie enhanced WIN self-administration in OBX rats.

Pilot study validating the animal model of depression – the bilateral olfactory bulbectomy in rats – by two nuclear magnetic resonance methods, indirectly detecting the metabolic state of the brain...

Depression is a psychiatric disorder characterized by a marked decrease in reward sensitivity. By using the olfactory bulbectomy (OBX) model of depression, it was shown that OBX rats display enhanced drug-taking and seeking behaviors in a self-administration paradigm than sham-operated (SHAM) controls, and sex is an important regulating factor. To reveal potential strain effects, we compared the operant behavior of male and female Sprague–Dawley and Wistar OBX and SHAM rats trained to self-administer palatable food pellets. Results showed that Sprague–Dawley OBX rats of both sexes exhibited lower operant responding rates and food intake than SHAM controls. Food restriction increased responding in both OBX and SHAM groups. Female rats responded more than males, but the OBX lesion abolished this effect. In Wistar rats, bulbectomy lowered food self-administration only during the last training days. Food self-administration was not significantly affected in Wistar rats by sex. In summary, this study showed that bulbectomy significantly reduces operant responding and food intake in male and female Sprague–Dawley rats while inducing a mild reducing effect only in the Wistar strain. Strain-dependent effects were also observed in the modulating role of sex and food restriction on operant responding and palatable food intake.

Comorbidity of depression and drug addiction is common, but effective treatment is missing. A rat model combining the olfactory bulbectomy (OBX) model and IV drug self-administration has provided e...