Histomorphological changes in the common carotid artery of the male rat in induced hypogonadism

Abstract

The role of androgens in the development of cardiovascular diseases remains controversial. The current study therefore sought to determine the changes in the histomorphology of the common carotid artery of the male rat in orchidectomy-induced hypogonadism. Twenty-two Rattus norvegicus male rats aged 2 months were used. The rats were randomly assigned into baseline (n=4), experimental (n=9), and control (n=9) groups. Hypogonadism was surgically induced in the experimental group by bilateral orchiectomy under local anesthesia. At experiment weeks 3, 6, and 9, three rats from each group (experimental and control) were euthanized, their common carotid artery harvested, and routine processing was done for paraffin embedding, sectioning, and staining. The photomicrographs were taken using a digital photomicroscope for morphometric analysis. Orchidectomy resulted in the development of vascular fibrosis, with a significant increase in collagen fiber density and decrease in smooth muscle and elastic fiber density. Moreover, there was development of intimal hyperplasia, with fragmentation of medial elastic lamellae in the common carotid artery of the castrated rats. Orchidectomy induces adverse changes in structure of the common carotid artery of the male rat. These changes may impair vascular function, therefore constituting a possible structural basis for the higher incidences of cardiovascular diseases observed in hypogonadism.

Reversible effect of castration induced hypogonadism on the morphology of the left coronary arteries in adult male rabbits

“…We reported a reduction of smooth muscle cell density of the tunica media of the LCAs in castrated adult male rabbits. Similar findings have been noted in the smooth muscle of the common carotid artery [21] and the penis [39] under settings of induced hypogonadism. Smooth muscle density increased to control levels in adult male castrated rabbits subsequently injected with testosterone, suggesting a reversible effect.…”

“…The present study demonstrates increased collagen fiber density in the tunica adventitia of the LCAs in hypo-androgenic rabbits. Other studies have reported similar changes in collagen fibers in the common carotid artery [21] and the penis [39] under induced androgen deficiency. We also found that vascular adventitial collagen fiber density remained elevated after administering testosterone to castrated rabbits.…”

“…We also noted a significantly lower IMT in castrated rabbits that subsequently received testosterone injections. Cheruiyot et al [ 21 ] similarly demonstrated increased IMT in common carotid arteries of hypogonadal rats. Few other studies indicate an inverse relationship between IMT and serum testosterone levels [ 17 , 19 ], but an indication of whether testosterone administration would reverse the effects of hypogonadism on the vascular structure is barely reported.…”

“…The variables we obtained included IMT, volumetric densities of adventitial collagen, and volumetric densities of smooth muscle. These measurements were obtained using standard morphometric methods in a past study on muscular arteries [ 21 ]. The collected data were then entered into the SPSS version 21 (IBM Co.) for coding, tabulation, and statistical analysis.…”

“…Most experimental studies have focused on changes in large-sized arteries induced by altering testosterone levels. Reported vascular structural changes under the setting of hypogonadism include increased carotid intima-media thickness (IMT) [ 19 ], increased collagen fiber density in the aorta [ 20 ], and decreased muscle density of carotid arteries [ 21 ]. Some evidence highlights that androgens have varying effects on different vascular beds [ 22 ].…”