Mechanisms of vasorelaxation induced by N-allylsecoboldine in rat thoracic aorta

The role of resistin on metabolic syndrome-induced erectile dysfunction and the possible therapeutic effect of Boldine

BACKGROUND

Resistin is known as a potential mediator of obesity-associated insulin resistance. The high resistin level disrupts nitric oxide (NO)-mediated relaxation which is also important in erectile function. An antioxidant alkaloid, Boldine, is known as anti-diabetic and protects endothelial functions.

OBJECTIVES

We aimed to investigate resistin expression in penile tissue in the presence of insulin resistance (IR) and the effect of Boldine treatment on erectile functions in the metabolic syndrome (MetS) rat model.

MATERIALS AND METHODS

Wistar rats were randomly divided into three groups: Control, MetS, and boldine treated MetS group. MetS parameters were assessed by serum triglycerides (TG), uric acid (UA), glucose, insulin levels, HOMA index, and waist circumference (WC)/tibia length (TL) ratio. To evaluate erectile functions, intracavernous pressure (ICP)/mean arterial pressure (MAP) ratio was performed during cavernous nerve stimulation. Protein expressions of resistin, endothelial nitric oxide synthase (eNOS), p(S1177) eNOS, and insulin receptor-β were evaluated by Western blotting.

RESULTS

TG, glucose, insulin levels, weight, WC/TL ratio, HOMA index and resistin expression in penile tissue were significantly increased and ICP/MAP values, and p (S1177) eNOS expression in penile tissue were decreased in MetS group. Boldine treatment enhanced ICP/MAP values, insulin receptor-β and p(S1177) eNOS expressions compared with the MetS group.

DISCUSSION AND CONCLUSION

MetS caused a deterioration in erectile function accompanied by an increase in resistin expression and a reduction in eNOS enzyme activation in the rat penile tissues. Boldine treatment resulted in an improvement in erectile function, independent of resistin expression.

In vitro functional evaluation of isolaureline, dicentrine and glaucine enantiomers at 5-HT2 and α1 receptors

Compounds with activity at serotonin (5-hydroxytryptamine) 5-HT₂ and α₁ adrenergic receptors have potential for the treatment of central nervous system disorders, drug addiction or overdose. Isolaureline, dicentrine and glaucine enantiomers were synthesized, and their in vitro functional activities at human 5-HT₂ and adrenergic α₁ receptor subtypes were evaluated. The enantiomers of isolaureline and dicentrine acted as antagonists at 5-HT₂ and α₁ receptors with (R)-isolaureline showing the greatest potency (pK_b  = 8.14 at the 5-HT_2C receptor). Both (R)- and (S)-glaucine also antagonized α₁ receptors, but they behaved very differently to the other compounds at 5-HT₂ receptors: (S)-glaucine acted as a partial agonist at all three 5-HT₂ receptor subtypes, whereas (R)-glaucine appeared to act as a positive allosteric modulator at the 5-HT_2A receptor.

Monoaminergic, Ion Channel and Enzyme Inhibitory Activities of Natural Aporphines, their Analogues and Derivatives

The aporphine alkaloids constitute the second-largest group of isoquinoline alkaloids. Nevertheless, only a relatively small number of natural aporphines and their derivatives have been studied from a pharmacological viewpoint. Here we review the pharmacological data available for these compounds as related to their dopaminergic, noradrenergic and serotonergic activities, and also some results pertaining to their effects on ion channels and enzymes.