A turbomachine with counter-rotating turbine for an aircraft, comprising: - a high-pressure body comprising a high-pressure compressor rotor and a high-pressure turbine rotor, these rotors being connected by a high-pressure shaft, - a low-pressure counter-rotating turbine, a first rotor of which is configured to rotate in a first direction of rotation and is connected to a first turbine shaft, and a second rotor of which is configured to rotate in an opposite direction of rotation and is connected to a second turbine shaft, the first rotor comprising turbine wheels interposed between turbine wheels of the second rotor, - a mechanical reduction gear with epicyclic gear train of the planetary type which comprises a sun gear driven in rotation by said second shaft, a ring gear driven in rotation by said first shaft, and a planet carrier attached to a first stator casing of the turbomachine located upstream of the counter-rotating turbine with respect to a direction of flow of the gases in the turbomachine, - first bearings (60, 62) for guiding said first turbine shaft, these first bearings being carried by at least one bearing support (61, 63) attached to a second stator casing located downstream of the counter-rotating turbine, characterised in that said reduction gear and said first bearings (60, 62) are housed in a first lubrication chamber fed with oil and comprising dynamic seals (86a-86d), and in that the turbomachine comprises: - a first circuit for pressurizing at least one of said seals (86a, 86d), the first circuit being configured to convey pressurized air from the external periphery of the high-pressure body to the external periphery of said second casing and then from the external periphery of that casing to its internal periphery and said at least one of said seals, and - a second circuit for pressurizing at least one other of said seals (86b, 86c, 86d), the second circuit being configured to convey pressurized air from the internal periphery of the high-pressure body to the internal periphery of said reduction gear and said at least one other of said seals, passing within said second shaft. - a high-pressure body comprising a high-pressure compressor rotor and a high-pressure turbine rotor, these rotors being connected by a high-pressure shaft, - a low-pressure counter-rotating turbine, a first rotor of which is configured to rotate in a first direction of rotation and is connected to a first turbine shaft, and a second rotor of which is configured to rotate in an opposite direction of rotation and is connected to a second turbine shaft, the first rotor comprising turbine wheels interposed between turbine wheels of the second rotor, - a mechanical reduction gear with epicyclic gear train of the planetary type which comprises a sun gear driven in rotation by said second shaft, a ring gear driven in rotation by said first shaft, and a planet carrier attached to a first stator casing of the turbomachine located upstream of the counter-rotating turbine with respect to a direction of flow of the gases in the turbomachine, - first bearings (60, 62) for guiding said first turbine shaft, these first bearings being carried by at least one bearing support (61, 63) attached to a second stator casing located downstream of the counter-rotating turbine, characterised in that said reduction gear and said first bearings (60, 62) are housed in a first lubrication chamber fed with oil and comprising dynamic seals (86a-86d), and in that the turbomachine comprises: - a first circuit for pressurizing at least one of said seals (86a, 86d), the first circuit being configured to convey pressurized air from the external periphery of the high-pressure body to the external periphery of said second casing and then from the external periphery of that casing to its internal periphery and said at least one of said seals, and - a second circuit for pressurizing at least one other of said seals (86b, 86c, 86d), the second circuit being configured to convey pressurized air from the internal periphery of the high-pressure body to the internal periphery of said reduction gear and said at least one other of said seals, passing within said second shaft. - a first circuit for pressurizing at least one of said seals (86a, 86d), the first circuit being configured to convey pressurized air from the external periphery of the high-pressure body to the external periphery of said second casing and then from the external periphery of that casing to its internal periphery and said at least one of said seals, and - a second circuit for pressurizing at least one other of said seals (86b, 86c, 86d), the second circuit being configured to convey pressurized air from the internal periphery of the high-pressure body to the internal periphery of said reduction gear and said at least one other of said seals, passing within said second shaft.