Performance of motor associated behavioural tests following chronic nicotine administration

Impact of dietary vitamin A on striatal function in adult rats

The striatum is a brain structure involved in the control of voluntary movement. Striatum contains high amounts of retinoic acid, the active metabolite of vitamin A, as well as retinoid receptors, RARβ and RXRγ. Previous studies revealed that disruption of retinoid signaling initiated during development is deleterious for striatal physiology and related motor functions. However, the alteration of retinoid signaling, and the importance of vitamin A supply during adulthood on striatal physiology and function has never been established. In the present study, we investigated the impact of vitamin A supply on striatal function. Adult Sprague-Dawley rats were fed with three specific diets, either sub-deficient, sufficient, or enriched in vitamin A (0.4, 5, and 20 international units [IU] of retinol per g of diet, respectively) for 6 months. We first validated that vitamin A sub-deficient diet in adult rats constitutes a physiological model of retinoid signaling reduction in the striatum. We then revealed subtle alterations of fine motor skills in sub-deficient rats using a new behavioral apparatus specifically designed to test forepaw reach-and-grasp skills relying on striatal function. Finally, we showed using qPCR analysis and immunofluorescence that the striatal dopaminergic system per se was not affected by vitamin A sub-deficiency at adult age. Rather, cholinergic synthesis in the striatum and μ-opioid receptor expression in striosomes sub-territories were the most affected by vitamin A sub-deficiency starting at adulthood. Taken together these results revealed that retinoid signaling alteration at adulthood is associated with motor learning deficits together with discrete neurobiological alterations in the striatum.

Neuromodulatory roles of PIPER GUINEENSE and honey against Lead-Induced neurotoxicity in social interactive behaviors and motor activities in rat models

Background

Piper guineense and honey contain antioxidative, anti-inflammatory, and antimicrobial properties that can help restore neuronal and other cell damage. To investigate the neuromodulatory roles of p. guineense and honey against lead toxicity on the hippocampus and cerebellum, impairing social behaviors and motor activities.

Methodology

Thirty Wistar rats were separated into six groups of five rats each, marked with dye. Group A served as control; B was untreated lead; C was a medium dose of the extract (50 mg/kg) and honey (1000 mg/kg); D was a high dose of the extract (80 mg/kg) and honey (1500 mg/kg); E received extract (80 mg/kg), and F received honey (1500 mg/kg). All groups received 110 mg/kg of lead orally, except the control. Social interaction, antidepressant effects, and motor activities were studied using a sociability chamber (SC), Forced Swim Test (FST), and String methods. A blood sample was used to evaluate glutathione peroxidase (GPx) and glutathione oxide transaminase (GOT), while the lipid level was estimated using cerebellar homogenate. Neuronal damage, vacuolation, necrosis, cell degeneration, and alterations in both hippocampus and cerebellum marked untreated group, with decreased GPx and GOT activities followed by impaired motor activities, social behavior, memory, and motivation. Using SCT, group B spent significantly lesser time (47.60 ± 47.60) with stranger 1 compared to A (138.20 ± 34.05), while group C spent considerably more time with stranger 1 (86.80 ± 30.32) than group B at P ≥ 0.05. The treatment increased the enzyme level and restored histoarchitecture (Figures 1-12), improving motor activities, social behavior, memory, motivation, and social affiliation (Tables 3, 4, 2, and 6). The extract and honey may be helpful as neuromodulators in lead toxicity in a dose-dependent manner.