Effects of unilatral‐ and bilateral inhibition of rostral ventral tegmental area and central nucleus of amygdala on morphine‐induced place conditioning in male Wistar rat

Abstract

Summary The rostral ventral tegmental area (VTAR) and central nucleus of amygdala (CeA) are considered the main regions for induction of psychological dependence on abused drugs, such as morphine. The main aim of this study was to investigate the transient inhibition of each right and left side as well as both sides of the VTAR and the CeA by lidocaine (2%) on morphine reward properties using the conditioned place preference (CPP) method. Male Wistar rats (250±20 g) 7 days after recovery from surgery and cannulation were conditioned to morphine (7.5 mg/kg) in CPP apparatus. Five minutes before morphine injection in conditioning phase, lidocaine was administered either uni‐ or bilaterally into the VTAR (0.25 μL/site) or CeA (0.5 μL/site). The results revealed that lidocaine administration into the left side, but not the right side of the VTAR and the CeA reduced morphine CPP significantly. The reduction was potentiated when lidocaine was injected into both sides of the VTAR and the CeA. The number of compartment crossings was reduced when lidocaine was injected into both sides of the VTAR and the CeA as well as the left side. Rearing was reduced when lidocaine was injected into the right, but not the left side of the VTAR. Sniffing and rearing increased when animals received lidocaine in the right side and reduced in the group that received lidocaine in the left side of the CeA. It was concluded that the right and the left side of VTAR and the CeA play different roles in morphine‐induced activity and reward.

Crocin improved amyloid beta induced long‐term potentiation and memory deficits in the hippocampal CA1 neurons in freely moving rats

“…The rats were anesthetized with a mixture of ketamine hydrochloride (70 mg/kg, IP) + xylazine (10 mg/kg, IP) for stereotaxic surgery (Ghobadi, Sahraei, Meftahi, Bananej, & Salehi, ; Mohammadian, Sahraei, Meftahi, & Ali‐Beik, ; Sadeghi‐Gharajehdaghi et al, ). The stereotaxic coordinates according to the Paxinos and Watson () atlas for frontal cortex was 3.2 mm AP, 3.6 mm DV, ML 4 mm relative to the bregma.…”

Effect of amygdaloid complex inhibition on nicotine-induced conditioned place preference in rats

“…Thus, it appears that these nuclei may be involved in reward behaviors of addictive drugs (Kelley and Berridge, 2002). In addition, studies also showed that the amygdala may be involved in the responses to stress and its function changes by stress as well (Asalgoo et al, 2015;Dalooei et al, 2016;Ghobadi et al, 2016;Mohammadian et al, 2016;Ehteram et al, 2017). Previous studies have indicated that LArginine, a precursor of nitric oxide, reinforces the role of morphine in inducing conditioned place preference in the central nuclei of the amygdala.…”

“…It is interconnected with many regions of the nervous system and induces a number of behaviors in animals (Campeau and Davis, 1995). Basolateral nucleus, as well as the cortical and the central nuclei, are connected to many cerebral structures such as the frontal cortex, the prefrontal cortex and the hippocampus, contributing to the integrity of behavior, stress and reward circuits (Mosher et al, 2010). Thus, it appears that these nuclei may be involved in reward behaviors of addictive drugs (Kelley and Berridge, 2002).…”