The hypocretin/orexin (HCRT) neuropeptide system modulates behavioral state and state-dependent processes

The hypocretin/orexin (HCRT) neuropeptide system modulates behavioral state and state-dependent processes via actions on multiple neuromodulatory transmitter systems. restricted populace of small-to-medium-sized DA neurons located within the caudomedial VTA. Furthermore, within this region of the VTA, PFC- and NAs-projecting TH-ir neurons were more likely to contain Fos-ir than were NAc-projecting TH-ir neurons. These results provide novel evidence that HCRT selectively activates PFC- and NAs-projecting DA neurons within the VTA, and suggest a potential role for INNO-406 manufacturer HCRT in PFC- and NAs-dependent cognitive and/or affective processes. Moreover, these and other observations suggest that the dysregulation of Rabbit Polyclonal to Ik3-2 HCRTCDA interactions could contribute to cognitive/affective dysfunction associated with a variety of behavioral disorders. access to food and water on an 13 : 11 h light : dark cycle (lights on 07:00 hours). Surgery All animals were stereotaxically implanted under halothane anaesthesia with a 26-gage guideline cannula (Plastics One, Roanoke, VA, USA) over the lateral ventricle (?1.0A, 1.35L, ?1.40V; coordinates in mm from Bregma with the head level). In a subset of animals, FG (Fluorochrome, Denver, CO, USA) was infused into the PFC (+2.9A, 1.0L), NAs (+1.3A, 1.1L) or NAc (+2.0A, 1.4L) contralateral to the i.c.v. cannula (observe below). For PFC infusions, pipettes were inserted at an angle of 4C6 from vertical toward midline, and three infusions were made at different dorsal-ventral levels (?2.2, ?3.0, ?4.2V) to increase protection. For NAc/NAs infusions, a single infusion was made at ?6.3 to 6.8V. Animals were allowed 7C10 days recovery following medical procedures. All facilities and procedures were in accordance with the guidelines regarding animal use and care put forth by the National Institutes of Health of the United States, and were supervised and approved by the Institutional Animal Care and Use Committee of the University or college of Wisconsin. FG infusions Iontophoretic FG infusions (2% in saline at 5.0 A, 15 min, 5-s pulses, 50% duty cycle) were made using single-barrel glass micropipettes (15C22 m tip diameter; Friedrich and Dimmock, Millville, NJ, USA) as previously explained (Valentino assessments to directly compare infusion sites. For all those three double-label combinations, two additional statistical assessments of identical design were conducted on large and small subsets of double-labeled cells. In all cases, statistical assessments were conducted on the number and percentage of double-labeled cells for the entire VTA, and for medial-rostral, lateral-rostral, medial-caudal and lateral-caudal divisions (observe Fig. 1). Results General observations In the current analyses, the distribution of TH-ir was consistent with previous descriptions of DA cell groups (Lindvall = 0.001). The magnitude of this effect appeared smaller than that previously observed in other brainstem areas (i.e. locus coeruleus, supramammillary nucleus; observe Espa?a = 0.51); therefore all subsequent analyses were limited to the VTA. HCRT-induced increases in Fos-ir in VTA TH-ir neurons To assess the degree to which HCRT activated VTA DA neurons, the mean quantity of Fos-ir + TH-ir double-labeled cells INNO-406 manufacturer was examined (AECF, = 6; HCRT, = 13; Fig. 2). Throughout the entire rostrocaudal extent of the VTA, HCRT resulted in a significant increase in the number (= INNO-406 manufacturer 0.002; Fig. 3A) and percentage of TH-ir cells made up of Fos-ir nuclei ( 0.001). When examined within the quadrants of the VTA as defined in Fig. 1, the most pronounced HCRT-induced increase in number (= 0.003; Fig. 3B) and percentage (= 0.004) of double-labeled (Fos-ir + TH-ir) cells INNO-406 manufacturer INNO-406 manufacturer occurred in the caudomedial VTA. Open in a separate windows Fig. 3 The number of tyrosine hydroxylase (TH)-ir neurons that were double-labeled with Fos-ir in the VTA in artificial extracellular fluid (AECF)-treated and hypocretin (HCRT)-treated animals. Presented are the number (mean + SEM) of TH-ir +.