The Journal of comparative neurology
-
Comparative Study
Characterization of CART neurons in the rat and human hypothalamus.
Cocaine- and amphetamine-regulated transcript (CART) is a recently described neuropeptide widely expressed in the rat brain. CART mRNA and peptides are found in hypothalamic sites such as the paraventricular nucleus (PVH), the supraoptic nucleus (SON), the lateral hypothalamic area (LHA), the dorsomedial nucleus of the hypothalamus (DMH), the arcuate nucleus (Arc), the periventricular nucleus (Pe), and the ventral premammillary nucleus (PMV). Intracerebroventricular administration of recombinant CART peptide decreases food intake and CART mRNA levels in the Arc are regulated by leptin. ⋯ Our results indicate that leptin directly acts on CART neurons in distinct nuclei of the rat hypothalamus. Furthermore, hypothalamic CART neurons coexpress neuropeptides involved in energy homeostasis, including MCH, TRH, DYN, and NT. The distribution of CART cell bodies and fibers in the human hypothalamus indicates that CART may also play a role in the regulation of energy homeostasis in humans.
-
An organotypic culture system of the early postnatal rat retina was developed to study microglial activation within a tissue environment. One day after tissue preparation, microglial cells of the ganglion cell/nerve fiber layer revealed features of activation. Cells acquired an ameboid morphology as revealed by Bandeiraea simplicifolia lectin staining. ⋯ Both the release from the tissue and the morphological changes of the microglia were reversible. Seventy-two hours after LPS removal, only microglia with ramified morphology were found, and release activities returned to baseline. These data suggest that the organotypic culture of the retina is a useful model for studying microglial activation from its resting form.
-
The ultrastructural features of neuronal nitric oxide synthase (NOS) -immunoreactive interneurons of rat nucleus accumbens shell and core were studied and compared. The NOS-containing subpopulation displayed characteristics similar to those previously described for nicotinamide adenine dinucleotide phosphate diaphorase-, neuropeptide Y, or somatostatin-containing striatal neurons, but also showed properties not previously associated with them, particularly the formation of both asymmetric and symmetric synaptic junctions. Inputs derived mainly from unlabeled terminals, but some contacts were made by NOS-immunolabeled terminals, by means of asymmetric synapses. ⋯ These results suggest that, in the rat nucleus accumbens, NOS-containing neurons may be further partitioned into subtypes, with differing connectivities in shell and core regions. These NOS-containing neurons may be influenced by a dopaminergic input. Recent studies suggest that nitric oxide potentiates dopamine release and the current study identifies the medium-sized, densely spiny neurons as a possible site of such an interaction.