Rat prostate: practical tips for ultrasonographic monitoring

Abstract

Background: Prostate is the largest accessory gland of the male reproductive tract. The prostate of men over 40 years-old is frequently affected by several pathologies, like benign prostate hyperplasia and cancer. Rats have been used as model to study prostate cancer. This study intended to address the usefulness of ultrasonography for rat prostate monitoring.

Material and methods: Eight male Wistar Unilever rats were acquired from Charles River Laboratories and maintained under controlled conditions of temperature, humidity, air system filtration and light/dark cycle. The prostate was evaluated by ultrasonography in awake animals. The animals were restrained by a researcher and placed in supine position. The skin of the inguinal region was shaved using a machine clipper (AESCULAP® GT420 Isis, USA). A real-time scanner (Logic P6®, GE, USA) and a 12 MHz linear transducer were used. Acoustic gel (Parker Laboratories Inc., USA) was applied. A complete transverse scan using B mode was performed from the cranial to the caudal region of the prostate, and a sagittal scan was performed moving the probe from the right to the left side. Procedures were approved by the Portuguese Ethics Committee (no.021326).

Results: Prostate was easily evaluated by ultrasonography in all animals. In the transverse scan, the urinary bladder presents as a round to oval shape filled with urine (anechoic structure) and the prostate lobes were visible around it. The ventral prostate lobes appear as hypoechoic elongated structures (one right and one left) with a hyperechoic capsule, placed ventrally to the urinary bladder. In this scan, the dorsal prostate was observed close to the urinary bladder neck, as a round hypoechoic structure with a hyperechoic capsule, dorsally to the urinary bladder. In the sagittal scan, the urinary bladder was observed as an elongated structure filled with urine (anechoic content). The ventral prostate lobes were occasionally observed ventrally to the neck of the urinary bladder, as previously described. The dorsal prostate was observed dorsally to the neck of the urinary bladder, presenting as a round to elongated shape, with a hypoechoic appearance and a hyperechoic capsule.

Conclusions: The ultrasonography is a non-invasive and accessible tool for prostate monitoring in the rat model.