Neuroscience
-
Parathyroid hormone receptor 2 (PTH2R) and its ligand, tuberoinfundibular peptide of 39 residues (TIP39) constitute a neuromodulator system implicated in endocrine and nociceptive regulation. We now describe the presence and distribution of the PTH2R and TIP39 in the brain of primates using a range of tissues and ages from macaque and human brain. In situ hybridization histochemistry of TIP39 mRNA, studied in young macaque brain, due to its possible decline beyond late postnatal ages, was present only in the thalamic subparafascicular area and the pontine medial paralemniscal nucleus. ⋯ The distribution of PTH2R-immunoreactive fibers in human, determined by immunocytochemistry, was similar to that in rodents, including dense fiber networks in the medial preoptic area, hypothalamic paraventricular, periventricular and infundibular (arcuate) nuclei, lateral hypothalamic area, median eminence, thalamic paraventricular nucleus, periaqueductal gray, lateral parabrachial nucleus, nucleus of the solitary tract, sensory trigeminal nuclei, medullary dorsal reticular nucleus, and dorsal horn of the spinal cord. Co-localization suggested that PTH2R fibers are glutamatergic, and that TIP39 may directly influence hypophysiotropic somatostatin containing and indirectly influence corticotropin releasing-hormone containing neurons. The results demonstrate that TIP39 and the PTH2R are expressed in the brain of primates in locations that suggest involvement in regulation of fear, anxiety, reproductive behaviors, release of pituitary hormones, and nociception.
-
A growing body of work has documented sex differences in many behavioral, neurochemical, and morphological responses to stress. Chronic stress alters morphology of dendrites in medial prefrontal cortex in male rats. However, potential sex differences in stress-induced morphological changes in medial prefrontal cortex have not been examined. ⋯ Brains were processed and neurons reconstructed as described in Experiment 1. Both sham-operated and ovariectomized rats with estradiol implants showed stress-induced increases in apical dendritic material, whereas ovariectomy without estradiol replacement prevented the stress-induced increase. Thus, the stress-induced increase in apical dendritic material in females is estradiol-dependent.
-
The lateral parafascicular nucleus (lPf) is a member of the intralaminar thalamic nuclei, a collection of nuclei that characteristically provides widespread projections to the neocortex and basal ganglia and is associated with arousal, sensory, and motor functions. Recently, lPf neurons have been shown to possess different characteristics than other cortical-projecting thalamic relay neurons. We performed whole cell recordings from lPf neurons using an in vitro rat slice preparation and found two distinct neuronal subtypes that were differentiated by distinct morphological and physiological characteristics: diffuse and bushy. ⋯ Retrogradely-labeled lPf neurons from frontal cortical fluorescent bead injections primarily consisted of bushy type lPf neurons (78%), but more importantly, all of these neurons were depolarized by muscarinic agonists. On the other hand, lPf neurons labeled by striatal injections were predominantly hyperpolarized by muscarinic agonists (63%). Our results indicate two distinct subpopulations of lPf projection neurons, and interestingly lPf neurons respond differentially to muscarinic receptor activation based on their axonal target.
-
Neural cell adhesion molecule (NCAM) is a membrane-bound cell recognition molecule that exerts important functions in normal neurodevelopment including cell migration, neurite outgrowth, axon fasciculation, and synaptic plasticity. Alternative splicing of NCAM mRNA generates three main protein isoforms: NCAM-180, -140, and -120. Ectodomain shedding of NCAM isoforms can produce an extracellular 105-115 kilodalton soluble neural cell adhesion molecule fragment (NCAM-EC) and a smaller intracellular cytoplasmic fragment (NCAM-IC). ⋯ NCAM-EC demonstrated a more gradual increase from the early postnatal period to reach a plateau by early adolescence, potentially implicating involvement in later developmental processes. In summary, this study implicates the major NCAM isoforms, PSA-NCAM and proteolytically cleaved NCAM in pre- and postnatal development of the human prefrontal cortex. These data provide new insights on human cortical development and also provide a basis for how altered NCAM signaling during specific developmental intervals could affect synaptic connectivity and circuit formation, and thereby contribute to neurodevelopmental disorders.