Effects of streptozotocin-induced diabetes and insulin on calcium responsiveness of the rat vas deferens

Insulin, but Not Metformin, Supports Wound Healing Process in Rats with Streptozotocin-Induced Diabetes

PURPOSE

Optimal glycemic control is crucial for proper wound healing in patients with diabetes. However, it is not clear whether other antidiabetic drugs support wound healing in mechanisms different from the normalization of blood glucose control. We assessed the effect of insulin and metformin administration on the wound healing process in rats with streptozotocin-induced diabetes.

METHODS

The study was conducted on 200 male Wistar rats with streptozotocin-induced diabetes. In the last phase of the study, 45 rats, with the most stable glucose levels in the range of 350-500 mg/dL, were divided into three groups: group I received human non-protamine insulin subcutaneously (5 IU/kg body mass) once a day, group II received metformin intragastrically (500 mg/kg b.m.), and group III (control) was given saline subcutaneously. After 14 days of antidiabetic treatment, a 2 cm × 2 cm thin layer of skin was cut from each rat's dorsum and a 4 cm disk with a hole in its center was sewn in to stabilize the skin and standardize the healing process. The wound healing process was followed up for 9 days, with assessment every 3 days. Biopsy samples were subjected to hematoxylin and eosin staining and immunohistochemical assays.

RESULTS

Analysis of variance revealed significant influence of treatment type (insulin, control, or metformin) on the relative change in wound surface area. The wound healing process in rats treated with insulin was more effective than in the metformin and control groups. Wound tissue samples taken from the insulin-treated animals presented significantly lower levels of inflammatory infiltration. Immunohistochemical assessment showed the greatest density of centers of proliferation Ki-67 in insulin-treated animals.

CONCLUSION

These results suggest that an insulin-based treatment is more beneficial than metformin, in terms of accelerating the wound healing process in an animal model of streptozocin-induced diabetes.

Antioxidant treatment ameliorates diabetes-induced dysfunction of the vas deferens in a rat model

Diabetes mellitus (DM) affects the male ejaculatory function. This study was designed to evaluate the role of oxidative stress in the development of diabetes-induced dysfunction of vas deferens (VD) in the rat. DM was induced by streptozotocin in 40 male Wistar rats. Subsequently, the diabetic animals were divided into three groups: DM group, DM + Eda group and DM + Tau group. These groups were administered saline, edaravone and taurine, respectively, daily for 4 weeks. Another group of ten rats served as a control group. DM was diagnosed in the 40 streptozotocin-injected rats. DM significantly reduced the VD weight. Additionally, DM induced in vitro VD hypercontractility, VD histological abnormalities and increased the serum and VD tissue concentration of malondialdehyde. VD immunohistochemistry revealed overexpression of three markers of oxidative stress. DM significantly reduced serum testosterone levels. No live birth was documented in all DM rats in mating experiments. Antioxidants significantly improved all the aforementioned parameters, except the testosterone levels. This study indicates a deleterious impact of DM-induced oxidative stress on VD histological and functional features. Antioxidant treatment may provide an adjunct tool to alleviate ejaculatory disorders for male patients with type 1 diabetes.

Effect of phenolic acids on functions of rat aorta, vas deferens and on metabolic changes in streptozotocin-induced diabetes

Objectives:

This study aimed to investigate the effects of antioxidant treatment on streptozotocin (STZ)-induced diabetic metabolic and smooth muscle (SM) complications in rats.

Materials and Methods:

Threeweeks after STZ injection (i.v.), vehicle, p-OH benzoic (p-OHBA), protocatechic (PA) and gallic acids (GA) were separately administered (10 mg/kg each, i.p.) to the rats everyday for 3 weeks. Metabolic functions were observedregularly. The rats in all groups were sacrificed andaorta and Vas deferens were dissected. Theresponses of isolated organs to agonists (acetylcholine and phenylephrine) were recorded.

Results:

Protocatechic acid prevented increase in food consumption and feces output significantly. The responses of isolated organs to agonists increased in the STZ-diabetic rats. The test drugs either prevented, exacerbated or didnot affect the SMchanges in the STZ-diabetic rats.

Conclusions:

It was concluded that p-OHBA, PA and GA may cause effects independently of their antioxidant effect and/or of diabeticcomplications. They may exhibit pro-oxidant activities in the experimental conditions applied.

Ejaculatory dysfunction in streptozotocin-induced diabetic rats: the role of testosterone

Hyperglycemic and hypoinsulinemic states caused by diabetes mellitus are usually related to some type of sexual dysfunction, resulting in infertility in humans and experimental models, mostly due to their effects on ejaculatory function. This study aimed to evaluate the possible role of testosterone in the restoration of normal ejaculatory function in diabetic rats. Male Wistar rats were randomly allocated into 3 experimental groups: control, diabetic (streptozotocin), and diabetic with testosterone supplementation (streptozotocin plus testosterone). The following parameters were assessed at the end of the experiment: body weight, circulating testosterone levels, number of spermatozoa ejaculated in the uterus through natural mating, and weight and in vitro isometric contractions of the vas deferens. Diabetic rats showed reduced plasma testosterone levels and ejaculatory dysfunction as observed by a lack in the spermatozoa ejaculated into the uterus of receptive females. In these diabetic rats, no difference was observed in the sensitivity of the vas deferens to norepinephrine, with or without the presence of the cocktail (cocaine plus propranolol). In spite of this, an increased sensitivity to methoxamine through the α1-adrenoceptor was observed. Testosterone supplementation did not restore these parameters to control values.We conclude that, in this experimental model, the lack of testosterone was not directly related to the diabetes-induced ejaculatory dysfunction.

Effects of Mexiletine on Electrical Field Stimulation-Induced Contractile Responses in the Ipsilateral and Contralateral Vasa Deferentia after Unilateral Testicular Torsion/Detorsion

AIM

To investigate testicular torsion-induced changes on the electrical field stimulation (EFS)-induced contractions in rabbit vasa deferentia and to evaluate the effect of mexiletine.

METHODS

18 male New Zealand albino rabbits were used in this experiment. Rabbits were divided into three groups: (1) control group (n = 6); (2) torsion group (n = 6), and (3) mexiletine group (n = 6). In the control group, vasa deferentia on both sides were harvested. In the torsion and mexiletine groups, the left testes of the rabbits were subjected to 720 degrees of clockwise torsion for 2 h and then detorsion was performed. In the mexiletine group, 50 mg/kg i.p. mexiletine was administered 1 h before detorsion. Following 24 h of the torsion, vasa deferentia on both sides were harvested and 2-cm strips including both the prostatic and epididymal portions were prepared to record EFS-induced contractions.

RESULTS

Testicular torsion caused a significant inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and contralateral vasa deferentia. Mexiletine treatment did not affect these inhibitory responses. Torsion/detorsion of the spermatic cord did not alter exogenously applied noradrenaline-induced contractions in both vasa deferentia. However, KCl-induced contractions diminished significantly in ipsilateral vas deferens of the torsion group and mexiletine restored this inhibition.

CONCLUSIONS

Unilateral testicular torsion/detorsion leads to inhibition in both phases of EFS-induced biphasic contractions of the ipsi- and contralateral vasa deferentia by causing a defect in presynaptic nerve transmission. However, mexiletine has no effect on this inhibition. Inhibition of the KCl-induced contractions in the ipsilateral vas deferens, which indicates postsynaptic tissue damage, is restored by administering mexiletine 1 h prior to detorsion.