Expression of estrogen receptors α and β in the trigeminal mesencephalic nucleus of adult women and men

Temporomandibular disorders are more prevalent in women than in men and phases of pain relate to the estrous cycle. Several studies described the location of estrogen receptors (ER) in the temporomandibular joint (TMJ), the masseteric muscles and cartilage, but it was unknown whether they are also expressed within the pseudounipolar neurons of the trigeminal mesencephalic nucleus, which receives direct sensory inputs from these structures. Therefore, we studied expression of ERα and ERβ protein in the trigeminal mesencephalic nucleus of ten human brains (five female/five male). Both receptors were uniformly expressed on neurons, but not other cell types within the target structure. Thus, sensory inputs from the TMJ and adjacent structures are likely to be modulated by estrogen at the level of the first sensory neuron which may underlie the well-known correlation of pain incidence and phases of the estrous cycle.