Prostate-thyroid axis: stimulatory effects of ventral prostate secretions on thyroid function.
BACKGROUND
Endocrine cells of the prostate secrete thyrotropin (TSH)-releasing hormone (TRH), TRH- and TSH-like peptides, and growth factors. Propylthiouracil- and methimazole-induced hypothyroidism increased prostatic levels of TRH in rats as in hypothalamus, whereas thyroxine (T4) replacement decreased TRH. From these reports, we inferred the existence of a prostate-thyroid axis.


METHODS
The influence of the prostate on the thyroid gland was studied in albino rats. Ventral prostate was surgically removed on day 31 postpartum. The animals were sacrificed on day 60 postoperation. Serum thyroid hormones were assayed by radioimmunoassay (RIA). For in vitro studies, normal thyroid and ventral prostate glands were cocultured with or without thyroid-stimulating hormone (TSH) antibody, to assess the direct influence of prostatic secretions on thyroid hormone secretion.


RESULTS
Serum total and free T4 and triiodothyronine (T3) were significantly reduced in ventral prostatectomized rats. Histological analysis of the thyroid showed that the diameters of the peripheral and middle follicles, colloid epithelial cells, and nuclei were increased in prostatectomized rats, indicating hypothyroid status. Total T3 and T4 were significantly elevated in the culture medium when thyroid and prostate were cocultured, irrespective of the presence of TSH antibody.


CONCLUSIONS
The present study suggests that ventral prostatic secretions have a stimulatory role on the thyroid gland.
Mani Maran
R R
RR
Department of Endocrinology, Dr. ALM Postgraduate Institute of Basic Medical Sciences, University of Madras, Chennai, India. michael@unimad.ernet.in
Subramanian
S
S
Rajendiran
G
G
Sunil
N
N
Archunan
G
G
Arunakaran
J
J
Govindarajulu
P
P
Aruldhas
M M
MM
D000375:Aging / Q000502:physiology; D000818:Animals; D008297:Male; D011467:Prostate / Q000378:metabolism / Q000502:physiology*; D011468:Prostatectomy; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D013268:Stimulation, Chemical; D013961:Thyroid Gland / Q000502:physiology*; D013963:Thyroid Hormones / Q000378:metabolism*
D013963:Thyroid Hormones