Presence of a highly efficient "binding" to bacterial contamination can distort data from binding studies

Microbial Endocrinology: An Ongoing Personal Journey

The development of microbial endocrinology is covered from a decidedly personal perspective. Specific focus is given to the role of microbial endocrinology in the evolutionary symbiosis between man and microbe as it relates to both health and disease. Since the first edition of this book series 5 years ago, the role of microbial endocrinology in the microbiota-gut-brain axis is additionally discussed. Future avenues of research are suggested.

Microbial endocrinology: Host-microbiota neuroendocrine interactions influencing brain and behavior

The ability of microorganisms, whether present as commensals within the microbiota or introduced as part of a therapeutic regimen, to influence behavior has been demonstrated by numerous laboratories over the last few years. Our understanding of the mechanisms that are responsible for microbiota-gut-brain interactions is, however, lacking. The complexity of the microbiota is, of course, a contributing factor. Nonetheless, while microbiologists approaching the issue of microbiota-gut-brain interactions in the behavior well recognize such complexity, what is often overlooked is the equal complexity of the host neurophysiological system, especially within the gut which is differentially innervated by the enteric nervous system. As such, in the search for common mechanisms by which the microbiota may influence behavior one may look for mechanisms which are shared by both host and microbiota. Such interkingdom signaling can be found in the shared production of neurochemical mediators that are found in both eukaryotes and prokaryotes. The study of the production and recognition of neurochemicals that are exactly the same in structure to those produced in the vertebrate organisms is known as microbial endocrinology. The examination of the microbiota from the vantage point of host-microbiota neuroendocrine interactions cannot only identify new microbial endocrinology-based mechanisms by which the microbiota can influence host behavior, but also lead to the design of interventions in which the composition of the microbiota may be modulated in order to achieve a specific microbial endocrinology-based profile beneficial to overall host behavior.

Rand Lecture, ASCEPT. GABA receptors: as complex as ABC? Australaisian Society for Clinical and Experimental Pharmacologists and Toxicologists

1. Receptors for the inhibitory neurotransmitter GABA are currently classified pharmacologically into two major subtypes. 2. GABAA receptors are antagonized by the convulsant alkaloid bicuculline, and are insensitive to activation by the GABA analogue baclofen. GABAB receptors are insensitive to bicuculline and activated stereoselectively by baclofen. 3. There is increasing evidence for 'novel' GABA receptors that pharmacologically fall outside that defined by the GABAA/B classification. 4. GABA receptors insensitive to both baclofen and bicuculline have been described in the spinal cord, optic tectum, retina, cerebellum and hippocampus. In addition such novel GABA receptors may be widespread in insects and bacteria. These novel receptors have been given a variety of descriptions: GABAC, GABANANB (non-A, non-B) and GABA rho (cloned from retina). 5. cis-4-Aminocrotonic acid (CACA), a structural analogue of GABA in a folded conformation, is considered to be a selective agonist of the putative GABAC receptors. Tritiated CACA binds to cerebellar membranes in a GABA-sensitive, baclofen-insensitive manner. It can be displaced only by relatively high concentrations of bicuculline. 6. Autoradiographic studies show pronounced differences in regional distribution between the binding of CACA, the GABAA agonist muscimol and the GABAB agonist baclofen. 7. Novel GABA receptors may represent important new pharmacological targets.