ABSTRACT
As neurones develop they are faced with choices as to which genes to express, to match their final phenotype to their role in the nervous system. A number of processes can guide these decisions. Within the autonomic and sensory nervous systems, there are a handful of examples that suggest that one mechanism that may match phenotype to function is the presence of target-derived differentiation factors. We tested whether the rat pineal gland controls the expression of a neuropeptide (neuropeptide Y) and a calcium-binding protein (calbindin) in sympathetic postganglionic neurones that innervate it. We first showed that the chemical phenotype of sympathetic neurones innervating the rat pineal includes the expression of both neuropeptide Y and the calcium-binding protein, calbindin. After transplanting the pineal gland of neonatal rats into the submandibular salivary gland of neonatal hosts, it was innervated by sympathetic axons from the surrounding salivary gland tissue, which do not normally express neuropeptide Y and calbindin. The presence of the pineal gland led to the appearance of neuropeptide Y and calbindin in many of the postganglionic neurones that innervated the graft. From these findings we suggest that, like the rodent sweat gland, the pineal gland generates a signal that can direct the neurochemical phenotype of innervating sympathetic neurones.
Subject(s)
Cell Communication/physiology , Cell Differentiation/physiology , Nerve Growth Factors/metabolism , Neuropeptide Y/metabolism , Pineal Gland/growth & development , Pineal Gland/innervation , S100 Calcium Binding Protein G/metabolism , Sympathetic Fibers, Postganglionic/growth & development , Animals , Axons/metabolism , Axons/ultrastructure , Calbindins , Female , Fluorescent Antibody Technique , Graft Survival/physiology , Male , Neurons/cytology , Neurons/metabolism , Phenotype , Pineal Gland/transplantation , Rats , Rats, Sprague-Dawley , Salivary Glands/innervation , Salivary Glands/metabolism , Salivary Glands/surgery , Skin Transplantation , Sympathetic Fibers, Postganglionic/cytology , Sympathetic Fibers, Postganglionic/metabolismABSTRACT
The calcium binding protein calbindin D28K is heterogeneously distributed in neurons throughout the body. We have investigated the distribution of calbindin in the chromaffin cells of the adult rodent adrenal medulla, which share the same developmental origin as peripheral sensory and autonomic neurons. Calbindin immunoreactivity was present in all noradrenergic chromaffin cells (defined by their lack of the adrenaline synthesizing enzyme, phenylethanolamine N-methyl transferase) in both the rat and mouse. It was also present in a very few adrenergic chromaffin cells in both rat and mouse. Calbindin-immunoreactivity is present in rat noradrenergic chromaffin cells from the day of birth and so is a useful marker for identifying rodent noradrenergic chromaffin cells.