Use of siRNA in knocking down of dopamine receptors, a possible therapeutic option in neuropsychiatric disorders

Abstract

Heightened dopaminergic activity has been shown to be implicated in some major neuropsychiatric disorders such as schizophrenia. Use of dopaminergic antagonists was limited by some serious side effects related to unspecific blocking of dopamine receptors. Thus a target specific dopamine receptor gene silencing method such as using small interfering RNA (siRNA) might be useful. In this study recombinant plasmids expressing siRNA against dopamine receptors (D1-D5DRs) were produced, and their efficiency in knocking down of receptors in were assessed in rat neuroblastoma cell line (B65), using Real-time PCR method. Furthermore, D2DR siRNA expressing plasmid was injected into the rat nucleus accumbens bilaterally to investigate whether it can prevent the hyperactivity induced by apomorphine. Locomotion was measured in 10 min intervals, 50 min before and 60 min after apomorphine injection (0.5 mg/kg, S.C). Our results indicated that the mRNA level of dopamine receptors were reduced between 25 and 75% in B65 cells treated with the plasmids in vitro. In behavioral tests, locomotion was lower at least in the second 10 min after apomorphine injection in rats treated with plasmid expressing D2DR siRNA compare to control group [F (4,24) = 2.77, (P < 0.05)]. The spontaneous activity of treated rats was normal. In conclusion, dopamine receptors can be downregulated by use of siRNA expressing plasmids in nucleus accumbens. Although our work may have some possible clinical applications; the potentially therapeutic application of siRNA in knocking down of dopamine receptors needs further studies.

Systemic Blockade of Dopamine D2-Like Receptors Increases High-Voltage Spindles in the Globus Pallidus and Motor Cortex of Freely Moving Rats

“…There was no significant difference between the control group and the AAV-shRNA-D 1 group in terms of locomotion (P = 0.31). In contrast, there was a significant decrease of locomotion in the AAV-shRNA-D 2 group compared with the control group and the AAV-shRNA-D 1 group (F [2], [21] = 28.039, n = 8, P<0.001; post-hoc Tukey test, both P<0.001; see Fig. 3B).…”

“…Prominent peaks around 7 Hz, which was within the frequency range associated with HVS activity, appeared in the rPSD of both the M1 cortex and the LFP in the GP. There was no significant effect of SCH23390 on the relative power in the frequency bands associated with HVS oscillations in either the M1 cortex or the GP, compared with saline-treated rats (F [2], [21] = 0.483, n = 8, P = 0.624, F [2], [21] = 0.193, n = 8, P = 0.826, respectively; see Fig. 4D).…”

“…There was no significant effect of SCH23390 on the number of HVSs compared with saline-treated rats (F [2], [21] = 1.111, n = 8, P = 0.348; see Fig. 4A).…”

“…There was a significant effect of raclopride on the duration of HVSs (F [2], [21] = 9.282, n = 8, P = 0.001). Raclopride at doses of 1.0 mg/kg (P = 0.005) and 3.0 mg/kg (P = 0.002) significantly increased the duration of HVSs compared with saline-treated rats.…”

“…Briefly, two 21-nucleotide sequences for the targeting of genes Drd1 (NM_012546, bp 227–245, GGTGACCAACTTCTTTGTC) and Drd2 (NM_012547, bp 451–469, CTACTATGCCATGCTGCTC) were selected in accordance with a previous publication [21]. A control sequence (TTCTCCGAACGTGTCACGT) was chosen on the basis of a previous report [22].…”