Intracavernosal Pressure Recording to Evaluate Erectile Function in Rodents

Summary

Intracavernosal pressure recording (ICP) is an important method to evaluate the erectile function of experimental animals. Here, a detailed protocol is demonstrated for the recording procedure of ICP by catheterizing the crura penis and then electrically stimulating the cavernous nerves in rats.

Abstract

Erectile dysfunction (ED) is defined as the inability to attain or keep an erection of the penis, and this has become a prevalent male sexual disorder. Rodents are employed by many studies to research the physiology/pathology of erectile function. Erectile function in rodents can be evaluated by measuring the intracavernosal pressure (ICP). In practice, ICP can be monitored following electrical stimulation of the cavernous nerves (CNs). The arterial pressure of the carotid artery (the mean arterial pressure) is used as the reference for ICP. Using ICP recording protocols, many key parameters of erectile function can be measured from the ICP response curve. The ICP measurement provides more information than the apomorphine-induced penile erection test, and is cheaper than telemetric monitoring of the corpus spongiosum penis, making this method the most popular one to evaluate erectile function. However, compared to the easily-performed APO-induced erectile function test, successful ICP recordings require attention to detail, practice, and adherence to the operation method. In this work, an introduction to ICP recording in rats is provided to complement the procedure efficiently.

Introduction

ED is defined as the inability to attain or keep a penile erection, and has become a common male sexual disorder¹. Experimental animals are used and provide reproducible models to investigate erectile function². For a long time, several larger animal models have been employed for investigating erectile function^3,4,5. Although rodents are relatively small compared to other animals, they are also used for the study of male erectile dysfunction due to exhibiting several advantages⁶. First, the morphological ....

Protocol

Three-month-old and 18-month-old Sprague-Dawley rats were used in the present study. All animals were handled in accordance with the NIH Guidelines for the Care and Use of Laboratory Animals. Procedures involving animal subjects were approved by the local Institutional Animal Care and Ethics Committee, with an effort to minimize animal suffering. The protocols were approved by the Institutional Animal Care and Use Committee (IACUC) at Nanjing Tech University (Nanjing, China).

The rats were divided into two groups according to their age and preliminary performance in the APO-induced erectile function test prior to ICP recording: the young no....

Results

Numerous studies have shown that erectile dysfunction in aged males is becoming a common problem. However, medical treatment is limited in the management of aging-related ED¹⁶. In rodent models of aging-related ED, many therapies are tested on the erectile function of aged rats. As we have introduced above, the ICP recording test could be used to distinguish the ED animals from the total population of experimental animals, which is also valuable to quantify the eff.......

Discussion

As a direct measure of erectile function, ICP is a reliable method¹⁴. It allows for the acquisition of data on basal ICP, peak ICP, plateau ICP, time to erection and detumescence time, duration of response, etc. Besides these direct measured parameters, there are some other index parameters: (1) "T80", the time to reach 80% of peak ICP; (2) "D20", the time to decrease to 20% of peak ICP; (3) "ΔT80", the rate of increase in pressure (per second) at T80; and (4).......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Animal
Rats			Strain: Sprague-Dawley Age: 2-3 month
Rats			Strain: Sprague-Dawley Age: 15-18 month
Name	Company	Catalog Number	Comments
Reagents
Saline	Sigma-Aldrich, S7653		dissolve 8.5 gram sodium chloride in distilled water
Pentobarbital sodium solution	Sigma-Aldrich, P3761		dissolve 1 gram in 100 ml saline
Povidone-iodine	BTP Pharmaceutical Co. Limited		10% (V/V)
Ethanol	China National Pharmaceutical Group Corporation (SINOPHARM)		70% (V/V)
Heparin	Sigma-Aldrich, H3149		dissolve 20000U heparin in 100 ml saline
Name	Company	Catalog Number	Comments
Materials
Hypodermic needle	Shandong Weigao Group Medical Polymer Co., Ltd.	23G
Syringe	Shandong Weigao Group Medical Polymer Co., Ltd	10 ml
Three-way stopcock	Chengdu Instrument factory	TSK 01
Electrode	Chengdu Instrument factory	JST-1
Catheter tube	Chengdu Instrument factory	PE-10, PE-50
Operating scissors	Shanghai operation equipment factory	J22010, J22020
Ophthalmic operating scissors	Shanghai operation equipment factory	Y00010, Y00020
Ophthalmic forceps	Shanghai operation equipment factory	JD1010, JD1020
MicroScissors	World Precision Instruments	WAA260
silk suture	Shandong Weigao Group Medical Polymer Co., Ltd.	5-0
Name	Company	Catalog Number	Comments
Equipment
Stimulator	Nanjing medease science and technology co. ltd (model 4C501H)		15 Hz, 5 ms pulse, 5 V, 60 s duration and 5 minutes interval
Multichannel signal collection processing system	Nanjing medease science and technology co. ltd (model 4C501H)		Blood pressure model
Pressure transducer	Beijing Xin Hang Xing Ye Technology Trading Company Limited (model YP100)		40KPa