Neurokinin B Administration Induces Dose Dependent Proliferation of Seminal Vesicles in Adult Rats

BACKGROUND

Neurokinin B; an endogenous decapeptide, mediates its reproductive physiological actions through gonadotropin releasing hormone. Despite the potential role of Neurokinin B on seminal vesicles, its effects on seminal vesicles in adult male mammals remain elusive. We aimed to investigate the potentials of variable doses of Neurokinin B, its agonist and antagonist on histomorphology and expression of NK3R on seminal vesicles, and secretory activity of seminal vesicles in adult male rats.

METHODS

Adult male Sprague Dawley rats (n=10 in each group) were administered intraperitoneally with Neurokinin B in three variable doses: 1 μg, 1 ηg and 10 ρg while, Senktide (Neurokinin B agonist) and SB222200 (Neurokinin B antagonist) in 1 μg doses consecutively for 12 days. After 12 days of peptide treatment, half of the animals (n=05) in each group were sacrificed while remaining half (n=05) were kept for another 12 days without any treatment to investigate treatment reversal. Seminal vesicles were dissected and excised tissue was processed for light microscopy, immunohistochemistry and estimation of seminal fructose levels.

RESULTS

Treatment with Neurokinin B and Senktide significantly increased while SB222200 slightly decrease the seminal vesicles weight, epithelial height and seminal fructose levels as compared to control. Light microscopy revealed increased epithelial height and epithelial folding as compared to control in all Neurokinin B and Senktide treated groups while decreased in SB222200. Effects of various doses of Neurokinin B, Senktide and SB222200 on seminal vesicles weight, epithelial height, seminal fructose levels and histomorphology were reversed when rats were maintained without treatments. Immuno-expression of Neurokinin B shows no change in treatment and reversal groups.

CONCLUSION

Continuous administration of Neurokinin B and Senktide effect positively while SB222200 have detrimental effects on cellular morphology, epithelial height and seminal fructose levels in seminal vesicles. Effects of peptide treatments depicted a reversal towards control group when rats were kept without any treatment.

Tachykinin antagonists ameliorate surgically induced impairment of gastrointestinal motility in rats

The protective effects of tachykinin receptor antagonists: SR140333 (NK₁ receptor), SR48968 (NK₂ receptor), and SB222200 (NK₃ receptor) were tested in rats against a surgically induced postoperative inhibition of gut motility, a common complication of abdominal surgery. The small intestinal transit of Evans blue was measured 24-h post-surgery in untreated rats and animals subjected to skin incision, laparotomy, or laparotomy followed by gut evisceration and manipulation. Surgical procedures were conducted under diethyl ether anesthesia. In comparison to untreated and ether-anesthetized rats, animals undergoing skin incision, laparotomy, or laparotomy with gut evisceration and manipulation showed a significant decrease in the intestinal transit of Evans blue. The pretreatment with NK₁ (3-100 µg/kg), NK₂ (3-30 µg/kg), and NK₃ (10-300 µg/kg) blockers before surgery ameliorated the inhibitory effects of gut manipulation in a dose-dependent manner. Moreover, the submaximal and maximal doses of NK₃ antagonists showed a trend toward reversing not only the inhibition caused by gut manipulation but also laparotomy. An additive effect of combining submaximal doses of NK_1-3 blockers was observed in animals pretreated with NK₁  + NK₂ compared to single-agent NK₁ and NK₂ . Additionally, doublets: NK₁  + NK₃ or NK₂  + NK₃ and a triplet: NK₁  + NK₂  + NK₃ proved to be more effective than NK₂ antagonist alone. In contrast, NK_1-3 blockers have not markedly affected the intestinal propulsion in untreated rats or animals subjected to skin incision or laparotomy. NK_1-3 blockers ameliorated the suppressed small-bowel gut motility 24 post-surgery. Combined pretreatment with NK_1-3 antagonists provided selective, additive benefits compared to single agents.

Tachykinin Antagonists Reverse Ischemia/Reperfusion Gastrointestinal Motility Impairment in Rats

BACKGROUND

Supraceliac aortic clamping and unclamping produces ischemia-reperfusion (I/R) injury of the splanchnic organs. The protective effects of tachykinin receptor antagonists, SR140333 (NK₁ receptor), SR48968 (NK₂ receptor), and SB222200 (NK₃ receptor), against I/R-induced inhibition of intestinal motility were tested in rats.

MATERIAL AND METHODS

The intestinal transit of Evans blue was measured in untreated rats and animals subjected to skin incision, I/R (1 h superior mesenteric artery occlusion followed by 24 h reperfusion) or sham operation. Surgical procedures were conducted under diethyl ether anesthesia.

RESULTS

The gastrointestinal transit has not been markedly affected in rats, which were anesthetized or subjected to skin incision in comparison with untreated animals. In contrast, a sham operation and I/R have significantly reduced the intestinal motility. Pretreatment with NK_1-3 blockers (SR140333 [3-30 μg/kg]; SR48968 [3-100 μg/kg]; and SB222200 [10-100 μg/kg]) reversed dose dependently the effects of I/R to the level observed after sham operation only. A combination of NK₁+NK₂+NK₃ inhibitors exerted an additive effect compared with NK₁ and NK₂ antagonists used as single agents. Similarly, combined NK₁+NK₂ were more effective than NK₂ alone. Sham operation and I/R have shifted the in vitro carbachol concentration-response curves to the right in comparison with untreated animals, a phenomenon partially reversed by NK₁-NK₃ pretreatment.

CONCLUSIONS

Single-agent and combined treatment with NK_1-3 antagonists markedly attenuated the gastrointestinal dysmotility evoked by I/R injury. The pretreatment with NK₃ blocker proved to be the most active in this experimental setting.