Neural Androgen Receptors Modulate Gene Expression and Social Recognition But Not Social Investigation

Abstract

The role of sex and androgen receptors (ARs) for social preference and social memory is rather unknown. In this study of mice we compared males, females and males lacking ARs specifically in the nervous system, AR(NesDel), with respect to social preference, assessed with the three-chambered apparatus test, and social recognition, assessed with the social discrimination procedure. In the social discrimination test we also evaluated the tentative importance of the sex of the stimulus animal. Novel object recognition and olfaction were investigated to complement the results from the social tests. Gene expression analysis was performed to reveal molecules involved in the effects of sex and androgens on social behaviors. All three test groups showed social preference in the three-chambered apparatus test. In both social tests an AR-independent sexual dimorphism was seen in the persistence of social investigation of female conspecifics, whereas the social interest toward male stimuli mice was similar in all groups. Male and female controls recognized conspecifics independent of their sex, whereas AR(NesDel) males recognized female but not male stimuli mice. Moreover, the non-social behaviors were not affected by AR deficiency. The gene expression analyses of hypothalamus and amygdala indicated that Oxtr, Cd38, Esr1, Cyp19a1, Ucn3, Crh, and Gtf2i were differentially expressed between the three groups. In conclusion, our results suggest that ARs are required for recognition of male but not female conspecifics, while being dispensable for social investigation toward both sexes. In addition, the AR seems to regulate genes related to oxytocin, estrogen and William's syndrome.

Keywords: autism; estrogen; knock-out; memory; sexual dimorphism; social behavior; three-chambered apparatus test.

FIGURE 1

Sociability measured with the three-chambered apparatus test in AR^NesDel males, male controls (wildtype, AR^flox, NesCre^+/-), and female controls (ARflox^+/-). (A) Amount of time spent in the each chamber during the 10 min test of sociability. (B) Amount of time spent sniffing the empty corral or the novel mouse. Bars represent mean ± SEM, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001 (within-group comparison) and ###p < 0.001, ####p < 0.0001 (between-group comparison).

FIGURE 2

Social investigation and social recognition measured in the social discrimination paradigm in AR^NesDel males, male controls (wildtype, AR^flox, NesCre^+/-), and female controls (ARflox^+/-). (A) Amount of time spent sniffing female stimulus animals in the sampling phase. (B) Social recognition of female stimulus animals. (C) Social memory score when presented to female stimulus animals. (D) Amount of time spent sniffing male stimulus animals in the sampling phase. (E) Social recognition of male stimulus animals. (F) Social memory score when presented to male stimulus animals. Bars represent mean ± SEM, ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗∗p < 0.0001 (for within-group comparison) and #p < 0.05 (for between-group comparison).

FIGURE 3

Sociability, social investigation and social recognition measured in the three-chambered apparatus test or the social discrimination paradigm in estrus and non-estrus female controls (ARflox^+/-). (A) Amount of time spent in each chamber and (B) sniffing the novel mouse during the 10 min test of sociability in the three-chambered apparatus. (C) Amount of time sniffing novel female and male stimulus mice in the sampling phase of the social discrimination paradigm. (D) Social memory score when presented to female or male stimulus animals. Bars represent mean ± SEM, ^∗p < 0.05, ^∗∗∗p < 0.001 (for within-group comparison).

FIGURE 4

Novel object recognition (NOR) memory test in AR^NesDel males, male controls (wildtype, AR^flox, NesCre^+/-), and female controls (ARflox^+/-). (A) Amount of time spent sniffing two similar objects. (B) Amount of time sniffing a familiar object or a novel. (C) Object memory score. Bars represent mean ± SEM, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001 (for within-group comparison).

FIGURE 5

Odor habituation/dishabituation in AR^NesDel males, male controls (wildtype, AR^flox, NesCre^+/-), and female controls (ARflox^+/-). Data points represent mean ± SEM.

FIGURE 6

Ar mRNA expression levels (A) in the hypothalamus and (B) in the amygdala of male AR^NesDel, as well as in male (wildtype, AR^flox, NesCre^+/-) and female (wildtype, ARflox^+/-) controls. The results are presented as percent (± SEM) in relation to the male control group. ^∗∗∗∗p < 0.0001.

FIGURE 7

mRNA expression levels of (A)Cd38(B)Cyp19a1(C)Oxtr(D)Ucn3, and (E)Esr1 in the hypothalamus of male AR^NesDel, as well as in male (wildtype, AR^flox, NesCre^+/-) and female (wildtype, ARflox^+/-) controls. The results are presented as percent (± SEM) in relation to the male control group. ^∗p < 0.05, ^∗∗p < 0.01.

FIGURE 8

mRNA expression levels of (A)Cd38, (B)Crh, (C)Cyp19a1, and (D)Gtf2i in the amygdala of male AR^NesDel, as well as in male (wildtype, AR^flox, NesCre^+/-) and female (wildtype, ARflox^+/-) controls. The results are presented as percent (± SEM) in relation to the male control group. ^∗p < 0.05, ^∗∗p < 0.01.