Fig. 4.

Effect of Mg²⁺ deficiency and diazepam treatment (1 mg/kg, i.p.) on behaviour and c-Fos expression in the paraventricular hypothalamic nucleus (PVN) of BALB/c mice following exposure to the open arm of an elevated plus maze. A. In mice fed a Mg²⁺ restricted diet the anxiety-related behaviour was elevated as indicated by the number of entries into the (anxiogenic) distal compartment of the open arm. Treatment with diazepam normalised this anxious phenotype. B. Compared with vehicle-treated controls, c-Fos induction was increased in the magnocellular portion of the PVN in Mg²⁺ deficient mice and was reversed by diazepam treatment. C. Representative photograph (scale bar = 100 μm) showing delineation of the PVN regions analysed with the help of a mouse brain atlas (Paxinos and Franklin, 2001). D. High magnification photograph showing c-Fos-positive cells in the magnocellular portion of the PVN in all experimental groups. Data represent mean ± SEM. n = 10 per experimental group. *P < 0.05, ***P < 0.001 for Mg²⁺ deficient vs. control mice, ^###P < 0.001 for diazepam vs. vehicle. 3V: third ventricle; DZP: diazepam; magno: magnocellular portion of the PVN; parvo: parvocellular portion of the PVN; V: vehicle.