MicroRNA-99a is a Potential Target for Regulating Hypothalamic Synaptic Plasticity in the Peri/Postmenopausal Depression Model

Abstract

Accumulating evidence has demonstrated that there is a growing trend of menopausal women suffering from depression. However, the pathogenesis of menopausal depression still remains unclear. Hence, this paper aims to reveal the pathological mechanisms involved in postmenopausal depression by using a novel peri- to postmenopausal depression model induced by a two-step ovariectomy plus chronic mild stress (CMS). The results of metabolic chambers and serum hormone/cytokine determination revealed that peri/postmenopausal depressive mice exhibited endocrine and metabolic disorders. Electrophysiological recordings indicated that the hippocampal synaptic transmission was compromised. Compared to the sham group, the microRNA-99a (miR-99a) level decreased significantly in the hypothalamus, and its target FK506-binding protein 51 (FKBP51) enormously increased; in contrast, the nuclear translocation of the progesterone receptor (PR) decreased in hypothalamic paraventricular nucleus (PVN) in the peri/postmenopausal depression mouse model. Additionally, synaptic proteins, including postsynaptic density protein 95 (PSD-95) and synaptophysin (SYN), showed a similar decrease in the hypothalamus. Accordingly, the present work suggests that miR-99a may be involved in the regulation of hypothalamic synaptic plasticity and that it might be a potential therapeutic target for peri/postmenopausal depression.

Keywords: FKBP51; hypothalamic synaptic plasticity; miR-99a; peri/postmenopausal depression; progesterone receptor.

Figure 1

Peri/postmenopausal depression disturbed neuroendocrine and metabolic activity. The insets on the left show the changing curves of weight (A), carbon dioxide production (B), oxygen consumption (C), physical activity (D), heat production (E), drinking (F), and feed (G) overtime between the sham group and the model group (CMS+UO+UO) across 24 h. The insets on the right of every section show the quantifications of the total alterations. (H) The detection of blood glucose in the two groups.

Figure 2

Peri/postmenopausal depression existed in an autonomic nervous dysfunctional and chronic inflammatory status and with synaptic transmission injury. (A–H) The expression of hormones and cytokines, including progestin, aldosterone, T3, insulin, S-100, IL-1β, TNF-α, and TGF-β in the blood, detected by ELISA. Data are presented as means ± SEMs, n = 4~5, ** p < 0.01, *** p < 0.001 versus sham. (I,J) Hippocampal synaptic LTP induced by high-frequency stimulation at 100 Hz was recorded in the sham group and in the CMS+UO+UO group.

Figure 3

The expression level of miR-99a was downregulated in the hypothalamus of peri/postmenopausal depressive mice. (A) The microRNA (miRNA) expression profile analyzed by a miRNA chip between the sham group and the CMS+UO+UO model. (B) Quantification of miRNAs in the two groups screened from the chip. (C) The miR-99a expression levels in the hypothalamus, hippocampus, corpus striatum, and prefrontal cortex were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). (D) MiR-99a bonds to the 3′UTR of FKBP51. Data are presented as means ± SEMs, n = 4–5, * p < 0.05, ** p < 0.01, *** p < 0.001 versus sham.

Figure 4

Hypothalamic progesterone (PR) nuclear translocation decreased and FKBP51 was upregulated in peri/postmenopausal depression. (A–C) The expression of FKBP51 in the hypothalamus was detected by western blot and immunofluorescence. (D–G) The expression of PR in the nucleus and cytoplasm of the hypothalamus was detected by western blot using Lamin b1 and GAPDH as loading controls. Data are presented as means ± SEMs, n = 4–5, ** p < 0.01, *** p < 0.001 versus sham; ^# p < 0.05, ^### p < 0.001 versus CMS group.

Figure 5

Hypothalamic synaptic plasticity injury in peri/postmenopausal depressive model mice. (A–D) The expression of synaptic proteins (PSD-95) and synaptophysin in the PVN in the sham, CMS, and CMS+UO+UO groups was detected by western blot and Immunofluorescence (IF). (E) The morphologies of synaptic structure in the hypothalamus in the sham, CMS, and CMS+UO+UO groups were detected by transmission electron microscope. Data are presented as means ± SEMs, n = 4–5, * p < 0.05, ** p < 0.01 versus sham.