If the release of thyroid hormone (th) was regulated by a long-loop negative feedback, where would you find the cells that are inhibited by the binding?

Hypothalamus and anterior pituitary gland.

Explanation:

Lower levels of T3 and T4 in the blood or lower metabolic rate serve as signal and stimulate the release of thyrotropin-releasing hormone (TRH) from the hypothalamus. The TRH stimulates the anterior pituitary gland to release thyroid-stimulating hormone (TSH) which in turn makes the thyroid gland to release the thyroid hormones.

The elevated levels of thyroid hormones inhibit the release of TRH from the hypothalamus and that of TSH from the anterior pituitary gland.

Hence, the cells of hypothalamus and anterior pituitary gland would be inhibited by the binding of thyroid hormone to regulate the release of these hormones by a negative feedback mechanism.

The cells that are inhibited by THE binding will be found in the anterior pituitary, and hypothalamus gland

Explanation:

Triiodothyronine (T3), and thyroxine (T4) are the two hormones present in blood. The lower level of these hormone stimulates the hypothalamus for the release of TRH (thyrotropine releasing hormone), which in turn stimulates the anterior pituitary gland for the release of TSH (thyroid stimualting hormone), due to which thyroid gland releases the thyroid hormone.

Likewise, the increased level of thyroid inhibits the release of TRH, and TSH from their respective glands. And this is how, the cells of anterior pituitary, and hypothalamus gland would be inhibited.