D2 antagonist during development decreases anxiety and infanticidal behavior in adult female prairie voles (Microtus ochrogaster)

Recent advances in dopamine D2 receptor ligands in the treatment of neuropsychiatric disorders

Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D_1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D₂ Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D₂ R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D₂ R affinity. Four to six atoms chains are optimal for D₂ R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D₂ R affinity. In this review, we provide a thorough overview of the therapeutic potential of D₂ R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D₂ R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D₂ R ligands and D₂ R modulators from patents are not discussed in this review.

Neonatal exposure to the D1 agonist SKF38393 inhibits pair bonding in the adult prairie vole

The monogamous prairie vole displays developmental sensitivity to early pharmacological manipulation in a number of species-typical social behaviors. The long-term consequences of altering the neonatal dopamine system are not well characterized. This study examined whether early manipulation of the dopamine system, a known mediator of adult prairie vole social behavior, during neonatal development would affect adult aggressive and attachment behaviors. Eight-day-old pups were given a single treatment with either 1 mg/kg of SKF38393 (D1 agonist), quinpirole (D2 agonist), SCH23390 (D1 antagonist), eticlopride (D2 antagonist), or saline vehicle. As adults, animals received tests for intrasexual aggression and partner preference. Activation of D1-like receptors in pups impaired partner preference formation, but had no effect on aggression. Other neonatal treatments had no effect on their behavior as adults. To determine whether D1 activation in pups induced changes in dopamine receptor expression, we performed autoradiography on striatal tissue from a second cohort of saline-treated and SKF38393-treated animals. Although sex differences were observed, we found no treatment differences in D1 or D2 receptor binding in any striatal subregion. This study shows that exposure to a single early pharmacological alteration of dopamine receptor activity may have long-term effects on the social behavior of prairie voles.

Genetics of aggression in voles

Prairie voles (Microtus ochrogaster) are socially monogamous rodents that form pair bonds-a behavior composed of several social interactions including attachment with a familiar mate and aggression toward conspecific strangers. Therefore, this species has provided an excellent opportunity for the study of pair bonding behavior and its underlying neural mechanisms. In this chapter, we discuss the utility of this unique animal model in the study of aggression and review recent findings illustrating the neurochemical mechanisms underlying pair bonding-induced aggression. Implications of this research for our understanding of the neurobiology of human violence are also discussed.