Adrenal Corticosteroidogenesis and Hypothyroidsm: Effect of Long-term Treatment with P-Aminobenzoic Acid

The relationship between induced hypothyroidism and adrenal involution has been studied by a variety of approaches in an attempt to elucidate the physiological basis between the events. McCarthy et al. (1959) reported on an investigation of feeding several antithyroidal agents to rats to study adrenal gland involution. While adrenal involution did occur following treatment with several of the goitrogens, only in one case was there a difference in peripheral plasma adrenal corticoid levels. In rats fed p-aminobenzoic acid (PABA) for 12 weeks, peripheral levels of corticosterone (B) decreased and levels of a Porter-Silber positive chromogen increased markedly. Work from the laboratories of Peron (1961) and of Birmingham (1961) established that the Porter-Silber chromogen in rat blood is 18-hydroxy-deoxycorticosterone (18-OH DOC). Cortes and Peron (1964) compared adrenal venous effiuent of normal and PABA-tested rats. These workers concluded that adrenal venous secretion of B and of 18-OH DOC by PABA-treated rats was unchanged from control values. Since the level of PABA fed has been shown to decrease thyroid function (McCarthy and Murphree, 1960), a question arose as to whether adrenal tissue from these hypothyroid rats would show any modification in corticosteroidogenesis. This study was undertaken to examine adrenal corticoid conversion in adrenal glands from rats fed PABA for various periods of time