Response of nitrergic system in the brain of rat conditioned to intracranial self-stimulation.

The role of nitrergic system in modulating the action of psychostimulants on reward processing is well established. However, the relevant anatomical underpinnings and scope of the involved interactions with mesolimbic dopaminergic system have not been clarified. Using immunohistochemistry, we track the changes in neuronal nitric oxide synthase (nNOS) containing cell groups in the animals conditioned to intracranial self-stimulation (ICSS) via an electrode implanted in the lateral hypothalamus-medial forebrain bundle (LH-MFB) area. An increase in the nNOS immunoreactivity was noticed in the cells and fibers in the ventral tegmental area (VTA) and nucleus accumbens shell (AcbSh), the primary loci of the reward system. In addition, nNOS was up-regulated in the nucleus accumbens core (AcbC), vertical limb of diagonal band (VDB), locus coeruleus (LC), lateral hypothalamus (LH), superficial gray layer (SuG) of the superior colliculus, and periaqueductal gray (PAG). The brain tissue fragments drawn from these areas showed a change in nNOS mRNA expression, but in opposite direction. Intracerebroventricular (icv) administration of nNOS inhibitor, 7-nitroindazole (7-NI) showed decreased lever press activity in a dose-dependent manner in ICSS task. While an increase in the dopamine (DA) and 3, 4-dihydroxyphenylacetic acid (DOPAC) efflux was noted in the microdialysates collected from the AcbSh of ICSS rats, pre-administration of 7-NI (icv route) attenuated the response. The study identifies nitrergic centers that probably mediate sensory, cognitive, and motor components of the goal-directed behavior.

Nuclear organization and distribution in the brain regions of the snake headed fish, Channa marulius.

BACKGROUND: Morphological variations have arisen due to diverse environmental conditions. Application of cytoarchitectonic criteria permits the delineation of distinct nuclear complexes from the brain region. PURPOSE: Very less information is available on the cytoarchitectonic pattern of the brain, of the giant snake headed murrel, Channa marulius. The murrel is much neglected in neuroanatomical terms and their study is a necessary step in tracing the evolutionary trends. Hence, in the present investigation, the brain of the snake headed fish, Channa marulius has been investigated to reveal the organization of different nuclear complexes. METHODS: Different nuclear complexes were identified and studied using Cresyl violet and Haematoxyline-Eosin staining techniques from the brain region of Channa marulius. RESULTS: Five distinct nuclear complexes namely pars medialis, pars centralis, pars lateralis dorsalis and pars lateralis ventralis respectively were observed in the area dorsalis telencephali and five nuclear groups pars ventralis, pars lateralis, pars dorsalis, pars supracommissuralis and nucleus entopeduncularis were identified in the area ventralis telencephali. CONCLUSIONS: Three nuclear groups namely pars posterioris, pars dorsalis, pars ventralis were identified in preoptic area. The inferior lobes are massive and consist of five circumscrible nuclear complexes. Midbrain consists of optic tectum, torus longitudinalis and tegmentum where different nuclear groups were identified.