Methods and systems for reducing neural activity in an organ of a subject

A catheter for ablating a duodenal wall, the catheter comprising:

• a laser transmitting element coupled with the catheter, the laser transmitting element configured to transmit a laser beam in a first direction parallel to a longitudinal axis of said catheter body;
• a rotatable optical element configured to direct the beam to be essentially perpendicular to the longitudinal axis of the laser emitting device and to enable rotational movement of the laser radiation emitted by the laser element around the longitudinal axis of the duodenum concomitantly with moving of the laser transmitting element along the duodenum, such that the emitted laser radiation generates a spiral-like or helical-like ablation pattern in the duodenal wall;
• and wherein the rotatable optical element is configured to focus the laser beam to a plurality of circumferentially and longitudinally spaced apart target areas around the wall of the duodenum, wherein the focused laser beam has a beam diameter of less than 1 mm at focal length in a range of 2-25 mm.