Islands of Calleja - Receptor Proteins

Receptor Proteins

• Bcl-2: The cells within the islands of Calleja that contain the Bcl-2 marker exhibit neuronal immaturity. They are numerous in the islands and are thought to aid in developing pathways for specific response.
• Cannabinoid receptor CB2: The cannabinoid receptors are a class of G protein-coupled receptors that bind either internally or externally produced cannabinoids. The CB2 variant was initially believed to be involved only with the cells in the immune system; however, they have been identified in the islands of Calleja and other structures of the limbic system, supporting the idea that this receptor has a neuronal function as well. This function has yet to be determined though. While the CB1 variant of the receptor has a pre-synaptic localization, it is thought that the CB2 receptors may possess a post-synaptic localization.
• Dopamine receptor D2: The islands of Calleja are different from other regions in the ventral striatum in that they actually exhibit no expression of this receptor.
• Dopamine receptor D3: These specific dopamine receptors exhibit different effects on cells depending on their location in the brain. In the islands of Calleja, their presence inversely affects an animal's interest in an unfamiliar area and the animal's tendency to form addictions. These receptors also contribute to the hypothermic response associated with a lowered room temperature in response to the drug Ecstasy.
• Muscarinic acetylcholine receptor M4: The muscarinic acetylcholine receptors are types of G protein-coupled receptors that regulate the effects of acetylcholine on the nervous system. In rodents, the core of the individual islands of Calleja contains high concentrations of the M4 receptor, whereas the peripheral granule cell clusters have lower concentrations, allowing each island to be easily visualized by staining for this specific receptor. The composition of the M4 receptors in the islands of Calleja in the brains of monkeys is similar to that of rodents; however, many of the islands, besides the major island, do not exhibit a noticeable core structure.
• Neurotensin receptor NTS3: Neurotensin is a neurotransmitter/neuromodulator associated with a number of functions, such as responses to pain, temperature, sleep-wake cycles, and dopamine. NTS3 is identical to the sorting protein sortilin and possesses many other functions outside the central nervous system. NTS3 is expressed in areas that also express the neurotensin receptor NTS1, including the islands of Calleja.
• Oxytocin receptor: Oxytocin is a molecule that induces maternal behaviors in animals. During childbirth, substantial increases in the expression of this receptor occur in the major island of the islands of Calleja. Furthermore, the extent of the increase depends on the mother's previous maternal experience. These changes within the islands of Calleja are connected to the differences in progesterone and estrogen levels during pregnancy.
• Phosphodiesterase 7B: Through the degradation of nucleotides, phosphodiesterases (PDE) produce cyclic adenosine monophosphate (cAMP), a molecule involved in sensory processing, neural plasticity, learning, and memory. Of the different families of phosphodiesterases, the 7B variant is one that bonds most easily to cAMP. Within the islands of Calleja, PDE7B is involved in the expression of the dopamine receptor D3. It may also be associated with transferring chemical information from the islands to other regions of the brain.
• Prokineticin: The islands contain the mRNA associated with the PK2 variant of the protein as well as the receptor variant PKR1. This class of proteins and receptors is partially responsible for the neurogenesis of cells in the olfactory bulb and certain reproductive behaviors, such as the hormonal events involved with the reproductive system.
• Serotonin 5-HT6 receptor: The serotonin 5-HT₆ receptor helps to increase neuronal cAMP production. Within the islands of Calleja and other structures of the striatum, these receptors may play a role in locomotor activity and memory.
• Syntrophin-associated serine/ threonine kinase (SAST): Syntrophin is an adaptor protein that connects other signaling proteins to dystrophin, a protein with major associations to muscular dystrophy. The SAST variant SAST124 is found in the islands of Calleja and other regions associated with the islands, such as the sub-ventricular zone and the olfactory bulb.