Near-infrared laser transcranial photobiomodulation for the treatment of chronic stress-induced low sexual desire in male mice.

Chronic stress can induce both depression and low sexual desire (LSD); however, selective serotonin reuptake inhibitors (SSRIs) may exacerbate LSD while being used to treat depression. It's known that sunlight could improve sexual desire, therefore we want to explore whether near-infrared laser transcranial photo-biomodulation (NIR-tPBM) could improves LSD caused by chronic stress. Forty-eight male eight-week-old Balb/c mice were divided into six groups; including chronic restraint stress (CRS) groups that received different levels of NIR-tPBM, the forced swim test and tail suspension test were used to evaluate depression in these mice. Ovariectomized and sex hormone induced sexual experienced female mice were used to evaluate the mating motivation of the male mice. The fraction of time spent sniffing a female (FTSSF) during the first five minutes of the pre-mounting period was used to evaluate the sexual desire, the function statues of the anteroventral and preoptic periventricular (AVPV/PVpo) dopaminergic neurons in the hypothalamus of the male mice were checked, the serum testosterone and cortisol were also measured. In mice undergoing CRS, NIR-tPBM improved both LSD and depression, with the ultimate effect related to radiant exposure level. The elevated c-Fos expression in AVPV/PVpo dopaminergic neurons induced by NIR-tPBM could be the reason for the improvement in LSD. While chronic stress led to LSD in male mice, we herein speculated that NIR-tPBM improved the LSD by activating AVPV/PVpo dopaminergic neurons in the hypothalamus.