The overuse of antibiotics in the healthcare and agricultural industries has led to the worldwide spread of bacterial resistance. The recent emergence of multidrug resistant (MDR) bacteria has resulted in a call for the development of novel strategies to address this global issue. Research on a diverse range of antimicrobial peptides (AMPs) has shown promising activity against several resistant strains. Increased understanding of the mode of action of AMPs has shown similarity and complementarity to conventional antibiotics and the combination of both has led to synergistic effects in some cases. Combination therapy has been widely used to combat MDR bacterial infections and the recent focus on their application with AMPs may allow antibiotics to be effective against resistant bacterial strains. By conjugation of an antibiotic onto an AMP, a compound may be produced with possibly greater activity and with reduced side-effects and toxicity. The AMP in these conjugates may also act as a unique adjuvant for the antibiotic by disrupting the resistance mechanisms used by bacteria thus allowing the antibiotic to once again be effective. This mini-review outlines some of the current and past work in combining AMPs with conventional antibiotics as strategies to address bacterial resistance.

The effect of intracerebroventricular (ICV) injections of synthetic human or rat relaxin (25 or 250 ng) on the distribution of Fos detected immunohistochemically in the rat forebrain was investigated. Following ICV relaxin, many Fos-positive neurons were observed in the periphery of the subfornical organ, dorsal part of the organum vasculosum of the lamina terminalis, throughout the median preoptic nucleus, supraoptic nucleus and hypothalamic paraventricular nucleus. Such effects did not occur following ICV injection of artificial cerebrospinal fluid or the separated A and B chains of relaxin, nor following the intravenous injection of 250 ng of relaxin. Both vasopressin and oxytocin containing neurons identified immunohistochemically in the supraoptic and paraventricular nuclei exhibited Fos following ICV relaxin, and many neurons in the medial parvocellular part of the paraventricular nucleus contained Fos. The results indicate that centrally administered relaxin may increase neuronal activity in regions of the hypothalamus and lamina terminalis which are associated with cardiovascular and body fluid regulation and oxytocin secretion.

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