Type 1 deiodinase activity and generation of triiodothyronine (T3) in prostate of sexually active rats.
BACKGROUND
Thyroxine (T(4)) and triiodothyronine (T(3)) are involved in the development and function of the male reproductive system. The type 1 deiodinase enzyme (D1) plays a major role in the intracellular conversion of T(4) to the active form, T(3). D1 is expressed in the prostate of pubescent rats, but it is unknown whether locally generated T(3) is involved in the development and function of this gland.


METHODS
D1 activity was analyzed in prostates from neonatal to old rats. Local T3 generation (D1 and T3 levels) was evaluated in adult animals with 1-5 months of continuous sexual activity. D1 activity was measured by the radiolabeled-iodide-release method and T(3) concentration by radioimmunoassay. Secretory activity of the prostate was evaluated by a morphological analysis of epithelium (hematoxilin-eosin stain) and by measuring the activity of acid phosphatase as a marker enzyme for secretion.


RESULTS
The highest prostate D1 activity was expressed around puberty, and it was almost undetectable during the neonatal period and with aging. Interestingly, 1 and 4 months of sexual activity avoided the decrease of D1 activity associated with aging. Sexual activity provoked a hypertrophy and functional hyperplasia in all lobes, but D1 and acid phosphatase activity increased only in the ventral lobe. D1 activity correlated with an increase in the prostatic T(3) concentration.


CONCLUSIONS
The increased local generation of T(3) in prostate might be related to: (1) the differentiation/maturation that occurs at puberty and (2) the energy expenditure associated with maintaining the secretory activity of the glandular epithelium.
López-Juárez
Alejandra
A
Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro 76230, México.
Delgado
Guadalupe
G
Aceves
Carmen
C
Anguiano
Brenda
B
D000135:Acid Phosphatase / Q000097:blood; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D005260:Female; D006651:Histocytochemistry; D007453:Iodide Peroxidase / Q000378:metabolism*; D008297:Male; D011467:Prostate / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation / Q000502:physiology; D013974:Thyroxine / Q000097:blood / Q000378:metabolism; D014284:Triiodothyronine / Q000096:biosynthesis* / Q000097:blood
D014284:Triiodothyronine; C109812:iodothyronine deiodinase type I; D007453:Iodide Peroxidase; D000135:Acid Phosphatase; D013974:Thyroxine