Ultrasound modulation of melatonin release from pineal glands in vitro

In this study, we aim to investigate whether therapeutic ultrasound can modulate the release of melatonin from the pineal gland-either increasing or decreasing its levels-and to assess the safety of this technique. This research could address a significant clinical need by providing a noninvasive method to potentially regulate sleep and circadian rhythms through the targeted modulation of melatonin.

Rat pineal glands were placed in a well with a Krebs Ringer Buffer solution. Ultrasound was applied to the glands using unfocused transducers set at an average intensity of 1 W/cm² and three different frequencies (400, 600, and 800 kHz) with continuous exposure for 5 min. Fluid samples were collected from the well before (t = 0 min), immediately after (t = 5 min), and 30 min post-ultrasound treatment (t = 30 min). Melatonin release was subsequently measured using an ELISA kit and analyzed statistically. In addition, histological analysis was completed to determine any structural abnormalities due to ultrasound application.

In the 600 kHz group there was a statistically significant decrease from t = 0 min to t = 5 min. No other statistically significant differences were observed. In addition, no histological changes were observed in the pineal glands due to ultrasound application.

This study indicated that ultrasound may be able to modulate melatonin release, however follow-up studies are necessary to determine optimal ultrasound parameters for this application.