This would be a question for your coach and/or trainers. Your body composition, weight distribution, and muscular development can all make a difference in whether 185 lbs is an appropriate weight. I'm not sure about sprinters, but I know decathletes routinely carry at least that much weight at that height, so it is possible if perhaps not ideal.
It also depends on what your goals are. If you want to be the best 400M runner possible, focus on what your coach tells you to do for training and pay less attention to your weight, whether it goes up or down. If you really really want to be over 185, consequences be damned, that's fine too, but realize that your weight has become more important to you than your 400M time.