Endocrine Abstracts

Twelve-month-old GK rats that showed glucose intolerance were compared with age matched Wistar rats. The concentrations of noradrenaline (NA), adrenaline (ADR) dopamine (DOP), Neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) were measured in tissue samples. The objective was to assess whether glucose intolerance was associated with changes in the noradrenergic and peptidergic nerves innervating the tail artery (TA), seminal vesicle (SV) and corpus cavernosum (CC), and the adrenal gland (AG). The tail artery was divided into three segments – proximal, middle and distal – of approximately 5 cm in length, because these contained the nerve endings of some of the longest nerves in the body of the rat.

Tail artery: In the tail artery, (NA) was significantly increased in the distal segments but was reduced proximally. (ADR) was unchanged proximally, but increased significantly in the middle and distal segments. (DOP) was always significantly less than the control levels, but increased from proximal to distal segments. (NPY) was significantly increased in the proximal and distal segments, and (CGRP) was significantly increased throughout the length of the artery, particularly in the proximal segment.

Seminal vesicle, corpus cavernosum and adrenal gland: (NA) increased significantly in the CC, but was reduced in the SV and AG. (ADR) was significantly reduced in the SV and AG, but unaffected in the CC. (DOP) was significantly increased in the ADR and CC, but fell in the SV. (NPY) and (CGRP) did not change in these tissues.

These changes indicate that there are significant changes in the longest peptidergic sensory and sympathetic axons in the 12 month-old GK rat, and the changes in (NA) in the distal tail artery and in the CC are similar to those described in the streptozotocin diabetic rat^1,2.

References

1. Morrison et al. Mol Cell Biochem 2004 261 77–82.

2. Morrison et al. Int J Impot Res 2007 19 509–516.