Dopamine D2 receptors in the dorsomedial prefrontal cortex modulate social hierarchy in male mice

Social hierarchy greatly influences behavior and health.Both human and animal studies have signaled the medial prefrontal cortex(mPFC)as specifically related to social hierarchy.Dopamine D1 receptors(D1Rs)and D2 receptors(D2Rs)are abundantly expressed in the mPFC,modulat-ing its functions.However,it is unclear how DR-expressing neurons in the mPFC regulate social hierarchy.Here,using a confrontation tube test,we found that most adult C57BL/6J male mice could establish a linear social rank after 1 week of cohabitation.Lower rank individuals showed social anxiety together with decreased serum testosterone levels.D2R expression was significantly downregulated in the dorsal part of mPFC(dmPFC)in lower rank individuals,whereas D1R expression showed no significant difference among the rank groups in the whole mPFC.Virus knockdown of D2Rs in the dmPFC led to mice being particularly prone to lose the contests in the confrontation tube test.Finally,simultaneous D2R activation in the subordinates and D2R inhibition in the dominants in a pair switched their dominant-subordinate relationship.The above results indicate that D2Rs in the dmPFC play an important role in social dominance.Our findings provide novel insights into the divergent func-tions of prefrontal D1Rs and D2Rs in social dominance,which may contribute to ameliorating social dysfunctions along with abnormal social hierarchy.

The expression analysis of silk gland-enriched intermediate-size non-coding RNAs in silkworm Bombyx mori

Small non-protein coding RNAs （ncRNAs） play important roles in development, stress response and other cellular processes. Silkworm is an important model for studies on insect genetics and control of Lepidopterous pests. We have previously identified 189 novel intermediate-size ncRNAs in silkworm Bombyx mori, including 40 ncRNAs that showed altered expression in different developmental stages. Here we characterized the functions of these 40 ncRNAs by measuring their expressions in six tissues of the fifth instar larvae using Northern blot and real-time polymerase chain reaction assays. We identified nine ncRNAs （four small nucleolar RNAs and five unclassified ncRNAs） that were enriched in silk gland, including four ncRNAs that showed silk gland-specific expression. We further showed that three of nine silk gland-enriched ncRNAs were predominantly expressed in the anterior silk gland, whereas another three ncRNAs were highly accumulated in the posterior silk gland, suggesting that they may play different roles in fibroin synthesis. Furthermore, an unclassified ncRNA, Bm- 152, exhibited converse expression pattem with its antisense host gene gartenzwerg in diverse tissues, and might regulate the expression of gartenzwerg through RNA-protein complex. In addition, two silk gland-enriched ncRNAs Bm-102 and Bm-159 can be found in histone modification complex, which indicated that they might play roles through epigenetic modifications. Taken together, we provided the first expression and preliminary functional analysis of silk gland-enriched ncRNAs, which will help understand the molecular mechanism of silk gland-development and fibroin synthesis.