ACER3-related leukoencephalopathy: expanding the clinical and imaging findings spectrum due to novel variants.

BACKGROUND: Leukodystrophies are the main subgroup of inherited CNS white matter disorders which cause significant mortality and morbidity in early years of life. Diagnosis is mostly based on clinical context and neuroimaging findings; however, genetic tools, particularly whole-exome sequencing (WES), have led to comprehending the causative gene and molecular events contributing to these disorders. Mutation in Alkaline Ceramidase 3 (ACER3) gene which encodes alkaline ceramidase enzyme that plays a crucial role in cellular growth and viability has been stated as an uncommon reason for inherited leukoencephalopathies. Merely only two ACER3 mutations in cases of progressive leukodystrophies have been reported thus far. RESULTS: In the current study, we have identified three novel variants in ACER3 gene in cases with new neurological manifestations including developmental regression, dystonia, and spasticity. The detected variants were segregated into family members. CONCLUSION: Our study expands the clinical, neuroimaging, electroencephalographic, and genetic spectrum of ACER3 mutations. Furthermore, we reviewed and compared the findings of all the previously reported cases and the cases identified here in order to facilitate their diagnosis and management.

Involvement of D1- and D2-like dopamine receptors within the rat nucleus accumbens in the maintenance of morphine rewarding properties in the rats.

Previous studies on drug abuse have shown that response to drug-associated cues exist during prolonged abstinence. In succession to previous investigations in our laboratory on morphine dependence and our research on acquisition and expression phases of morphine-conditioned place preference (CPP), in this study we attempt to determine the effects of intraaccumbal administration of SCH-23390, as a D1-like receptor antagonist, and sulpiride, as a D2-like receptor antagonist, in the maintenance of morphine-induced CPP in rats. Seventy-nine adult male Wistar rats weighing 200-280 g were bilaterally implanted with cannulas into the nucleus accumbens. During the 3-day conditioning phase, the animals received daily subcutaneous administration of morphine (5 mg/kg). CPP score and locomotor activity of animals were recorded by Ethovision software. Different doses (0.25, 1, 4 µg per 0.5 µL vehicle) of D1- and D2-like antagonists were bilateral injected daily after the expression phase and during the extinction phase. Our findings revealed that intraaccumbal administration of D1-like and D2-like antagonists after the CPP test shortened the extinction phase in the rats. The results suggested that the existence of the dopamine receptors in the nucleus accumbens was important for the maintenance of morphine-rewarding properties during the extinction phase. Therefore, dopamine receptors may be considered as a promising therapeutic agent in preventing the maintenance of morphine-rewarding effects in dependent individuals. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The Involvement of Intra-Hippocampal Dopamine Receptors in the Conditioned Place Preference Induced By Orexin Administration into the Rat Ventral Tegmental Area.

The activity of dopamine (DA)-containing neurons in the ventral tegmental area (VTA) is a key mechanism in mesolimbic reward processing that has modulatory effects on different diencephalic structures like hippocampus (HIP), and receives inhibitory feedback and excitatory feed forward control. In addition, within the hippocampus, DA receptors are mostly located in the dorsal part (CA1) and dopaminergic innervations are predominant in this sub-region. The current study aimed to examine the effect of intra-hippocampal CA1 administration of SCH23390 and Sulpiride as D1- and D2-like receptor antagonists on the acquisition of orexin-induced conditioned place preference (CPP), respectively. Cannulas were unilaterally implanted into the VTA and HIP of adult male albino Wistar rats weighing 200-250 g. For induction of CPP, orexin A (10 ng/0.3 µL saline) was daily microinjected into the VTA during a three-day conditioning phase. Thereafter, various doses of SCH23390 and Sulpiride (0.25, 1 and 4 µg) were unilaterally injected into the CA1 during this 3-day conditioning phase after intra-VTA administration. The conditioning score was then calculated. Results revealed that intra-CA1 administration of D1- and D2-like receptor antagonists during the 3-day conditioning phase attenuated the acquisition of place preference by orexin A in a dose-dependent manner. It seems the effect of D2-like receptor antagonist within the CA1 region of hippocampus on this phenomenon was found to be more considerable than that of D1-like receptor antagonist. It is concluded that orexin-induced CPP may be mediated, at least in part, by stimulation of DA receptors in the CA1.

Food deprivation facilitates reinstatement of morphine-induced conditioned place preference: Role of intra-accumbal dopamine D2-like receptors in associating reinstatement of morphine CPP with stress.

The high rate of relapse to drug use is one of the main problems in the treatment of addiction. Stress plays the essential role in drug abuse and relapse; nevertheless, little is known about the mechanisms underlying stress and relapse. Accordingly, the effects of intra-accumbal administration of Sulpiride, as a dopamine D2-like receptor antagonist, on an ineffective morphine dose + food deprivation(FD)- and morphine priming-induced reinstatement of conditioned place preference (CPP). About 104 adult male albino Wistar rats weighing 200-280 g were bilaterally implanted by cannula into the nucleus accumbens (NAc). Subcutaneous (sc) injection of morphine (5 mg kg-1 ) was used daily during a 3-day conditioning phase. After a 24-hr "off" period following achievement of extinction criterion, rats were tested for FD- and priming-induced reinstatement of morphine CPP by an ineffective (0.5 mg kg-1 , sc) and priming (1 mg kg-1 , sc) dose of morphine, respectively. In the next experiments, animals received different doses of intra-accumbal Sulpiride (0.25, 1, and 4 µg/0.5 µL saline) bilaterally and were subsequently tested for morphine reinstatement. Our findings indicated that the 24-hr FD facilitated reinstatement of morphine CPP. Furthermore, the D2-like receptor antagonist attenuated the ineffective morphine dose+ FD- and priming-induced reinstatement of morphine CPP dose-dependently. Also, contribution of D2-like receptors in mediation of the ineffective morphine dose+ FD-induced reinstatement of CPP was greater than morphine priming-induced reinstatement of CPP. The role of dopaminergic system in morphine reinstatement through a neural pathway in the NAc provides the evidence that D2-like receptor antagonist can be useful therapeutic targets for reinstatement of morphine CPP.

Differential roles of orexin receptors within the dentate gyrus in stress- and drug priming-induced reinstatement of conditioned place preference in rats.

Orexins are hypothalamic peptides involved in the modulation of the feeding, arousal, reward function, learning, and memory; nevertheless, the role of orexins in stress and relapse are largely unclear. Therefore, in the present study, the reinstatement model were used to examine the effects of intradentate gyrus (DG) administration of SB334867 as an orexin-1 receptor antagonist and TCS OX2 29, as an orexin-2 receptor antagonist on drug priming- and forced swim stress (FSS)-induced reinstatement of morphine. One-hundred and 44 adult male albino Wistar rats weighing 200 g-280 g were bilaterally implanted by cannulas into the DG. For induction of conditioned place preference (CPP), subcutaneous (sc) injection of morphine (5 mg/kg) was used daily during a 3-day conditioning phase. Then, the conditioning score (conditional stimulus [CS]) was calculated. After a 24 hr "off" period following achievement of extinction criterion, rats were tested for drug priming-induced reinstatement by priming dose of morphine (1 mg/kg, sc) and for FSS-induced reinstatement 10 min after FSS. In the next experiments, animals received different doses of intra-DG administration of SB334867 and TCS OX2 29 (3, 10, and 30 µg/0.5 µl 12% DMSO per side), bilaterally and were subsequently tested for morphine priming- and FSS-induced reinstatement. Our findings indicated that the FSS-induced the reinstatement of seeking behaviors. Furthermore, intra-DG administration of orexin-1 and orexin-2 receptor antagonists attenuated drug priming-induced reinstatement dose-dependently. However, they have trivial role in FSS-induced reinstatement. It is concluded that drug priming-induced reinstatement may be mediated, at least in part, by stimulation of orexin receptors in the DG.

Differential effects of intra-accumbal orexin-1 and -2 receptor antagonists on the expression and extinction of morphine-induced conditioned place preference in rats.

Orexinergic neurons originate from the hypothalamic nuclei, sending projections toward mesolimbic regions such as the nucleus accumbens (NAc). In this study, an attempt was made to determine the effects of intra-accumbal administration of SB334867 as an orexin-1 receptor (OX1R) antagonist and TCS OX2 29 as an orexin-2 receptor (OX2R) antagonist in the expression and maintenance of morphine-induced conditioned place preference (CPP) in rats. One hundred and five adult Wistar rats weighing 200-280g were bilaterally implanted with cannulae into the NAc. During the 3-day conditioning phase, animals received daily subcutaneous administration of morphine (5mg/kg). CPP score and locomotor activity of animals were recorded by Ethovision software. Different doses of bilateral injections of the OX1R and OX2R antagonists (3, 30 and 300µg/0.5µl DMSO) were administered just before the conditioning test or daily injection during extinction phase. Our finding revealed that intra-accumbal administration of OX1R not OX2R antagonist just before the CPP test attenuated the expression of the morphine-induced CPP. However, the blockade of these two kinds of receptors shortened the extinction phase in the rats. This effect was more significant in intra-NAc OX1R antagonist-treated animals. The results suggested that OX1R within the NAc may be necessary for the morphine-induced expression. Additionally, it seems that the existence of the orexin receptors in the NAc was important for the maintenance of morphine rewarding properties during the extinction phase. Therefore, orexins may be considered as a promising therapeutic agent in preventing the expression and maintenance of morphine rewarding effects on dependent individuals.

Role of dopamine D1-like receptor within the nucleus accumbens in acute food deprivation- and drug priming-induced reinstatement of morphine seeking in rats.

Dopamine is a predominant neurotransmitter in the nervous system, which plays an important role in both drug priming- and cue-induced reinstatement of cocaine and heroin seeking. Therefore, in the present study, the conditioned place preference (CPP) paradigm was used to evaluate the effects of intra-accumbal administration of SCH23390 as a dopamine D1-like receptor antagonist on food deprivation (FD) and drug priming-induced reinstatement. Sixty-eight adult male albino Wistar rats weighing 200-280 g were bilaterally implanted by cannulae into the nucleus accumbens (NAc). For induction of the CPP, subcutaneous (sc) administration of morphine (5mg/kg) was used daily during a three-day conditioning phase. The conditioning score and locomotor activity were recorded by using the Ethovision software. Under extinction conditions, rats were given an 'off' period and were tested for FD-induced reinstatement following the 24-h or 48-h FD condition, and for drug priming-induced reinstatement under the sated condition following an injection of 0.5 and 1mg/kg (sc) morphine. In the next experiments, animals received different doses of intra-accumbal SCH23390 (0.25, 1 and 4 µg/0.5 µl saline) bilaterally and were subsequently tested for FD- and morphine priming-induced reinstatement. Our findings indicated that only a dose of 1mg/kg and not 0.5mg/kg of morphine induced the reinstatement of morphine. 24-h FD similar to 48-h FD induced the reinstatement of seeking behaviors facilitated by an ineffective dose of morphine (0.5mg/kg). Furthermore, the D1-like receptor antagonist attenuated FD- and drug priming-induced reinstatement dose-dependently. It is concluded that FD- and drug priming-induced reinstatement may be mediated, at least in some way, by activation of dopamine D1-like receptors in the NAc.