Transient expression of neuropeptide W in postnatal mouse hypothalamus--a putative regulator of energy homeostasis.

Neuropeptide B and W (NPB and NPW) are cognate peptide ligands for NPBWR1 (GPR7), a G protein-coupled receptor. In rodents, they have been implicated in the regulation of energy homeostasis, neuroendocrine/autonomic responses, and social interactions. Although localization of these peptides and their receptors in adult rodent brain has been well documented, their expression in mouse brain during development is unknown. Here we demonstrate the transient expression of NPW mRNA in the dorsomedial hypothalamus (DMH) of postnatal mouse brain and its co-localization with neuropeptide Y (NPY) mRNA. Neurons expressing both NPW and NPY mRNAs begin to emerge in the DMH at about postnatal day 0 (P-0) through P-3. Their expression is highest around P-14, declines after P-21, and by P-28 only a faint expression of NPW and NPY mRNA remains. In P-18 brains, we detected NPW neurons in the region spanning the subincertal nucleus (SubI), the lateral hypothalamic (LH) perifornical (PF) areas, and the DMH, where the highest expression of NPW mRNA was observed. The majority of these postnatal hypothalamic NPW neurons co-express NPY mRNA. A cross of NPW-iCre knock-in mice with a Cre-dependent tdTomato reporter line revealed that more than half of the reporter-positive neurons in the adult DMH, which mature from the transiently NPW-expressing neurons, are sensitive to peripherally administrated leptin. These data suggest that the DMH neurons that transiently co-express NPW and NPY in the peri-weaning period might play a role in regulating energy homeostasis during postnatal development.

Roles of the glutamate receptor epsilon2 and delta2 subunits in the potentiation and prepulse inhibition of the acoustic startle reflex.

We examined the regulation of the acoustic startle response in mutant mice of the N-methyl-D-aspartate (NMDA)- and delta-subtypes of the glutamate receptor (GluR) channel, which play important roles in neural plasticity in the forebrain and the cerebellum, respectively. Heterozygous mutant mice with reduced GluRepsilon2 subunits of the NMDA receptor showed strongly enhanced startle responses to acoustic stimuli. On the other hand, heterozygous and homozygous mutation of the other NMDA receptor GluRepsilon subunits exerted no, or only small effects on acoustic startle responses. The threshold of the auditory brainstem response of the GluRepsilon2-mutant mice was comparable to that of the wild-type littermates. The primary circuit of the acoustic startle response is a relatively simple oligosynaptic pathway located in the lower brainstem, whilst the expression of GluRepsilon2 is restricted to the forebrain. We thus suggest that the NMDA receptor GluRepsilon2 subunit plays a role in the regulation of the startle reflex. Ablation of the cerebellar Purkinje cell-specific delta2 subunit of the GluR channel exerted little effect on the acoustic startle response but resulted in the enhancement of prepulse inhibition of the reflex. Because inhibition of the acoustic startle response by a weak prepulse is a measure of sensorimotor gating, the process by which an organism filters sensory information, these observations indicate the involvement of the cerebellum in the modulation of sensorimotor gating.

Characterization of nociceptin/orphanin FQ-induced pain responses in conscious mice: neonatal capsaicin treatment and N-methyl-D-aspartate receptor GluRepsilon subunit knockout mice.

Activation of primary afferent C fibers gives rise to spinal release of substance P and glutamate, and these mediators facilitate the cascade of nociceptive processing. We recently showed that intrathecal administration of nociceptin or orphanin FQ (hereafter called nociceptin) induced hyperalgesia to noxious thermal stimuli and allodynia to innocuous tactile stimuli applied to conscious mice. In the present study, we designed experiments to elucidate the pathways and mediators of nociceptin-evoked pain responses. Neonatal capsaicin treatment eliminated the induction of hyperalgesia and allodynia by nociceptin. Whereas this treatment markedly reduced the content of substance P in the spinal cord, it did not affect the nociceptin content or the expression of nociceptin receptors and GluRvarepsilon and GluRzeta subunits of N-methyl-D-aspartate receptors in it. The substance P antagonists CP96,345 and CP99,994 blocked the nociceptin-induced hyperalgesia, but not the allodynia. In contrast, the nociceptin-evoked allodynia, but not hyperalgesia, disappeared in N-methyl-D-aspartate receptor GluRvarepsilon1 subunit knockout mice. Both nociceptin-evoked hyperalgesia and allodynia were attenuated by morphine in a dose-dependent manner. Taken together, these results demonstrate that capsaicin-sensitive primary afferent fibers are involved not only in thermal hyperalgesia but also in tactile allodynia induced by nociceptin, but in different pathways; the former is mediated by substance P and the latter is mediated by glutamate through the N-methyl-D-aspartate receptor comprising the GluRvarepsilon1 subunit.

Instability of mutant Cu/Zn superoxide dismutase (Ala4Thr) associated with familial amyotrophic lateral sclerosis.

In about 20-25% of cases of familial amyotrophic lateral sclerosis (FALS) patients have mutations in the Cu/Zn superoxide dismutase (SOD1) gene. The mechanism through which the mutations in the SOD1 gene cause ALS still remain unknown. We performed pulse-chase experiments using a system for the transient expression of human SOD1 in COS7 cells to examine whether the Ala4Thr mutation, which we previously reported, decreases the stability of SOD1. The expression vector (pEF-BOS) carrying the wild-type or mutant (Ala4Thr) human SOD1 cDNA was transfected into COS7 cells, and transiently expressed human SOD1 was then metabolically radiolabeled. Half-lives of the wild-type and the Ala4Thr mutant SOD1 were determined to be 78 h and 18 h, respectively. These results suggest that the Ala4Thr mutation in SOD1 decreases the stability of SOD1 and that this instability may play an important role in the pathogenesis of the degeneration of motor neurons in FALS.

[Abscess of the abdominal wall following penetration of the descending colon: a rare complication of a ventriculoperitoneal shunt].

A case of abscess of the abdominal wall associated with a ventriculoperitoneal (V-P) shunt following penetration into the descending colon is reported. A 49-year-old male was diagnosed as having hypertensive intracerebellar hematoma with hydrocephalus, and he was treated by V-P shunt. One year later he experienced left hypochondrial pain with rebound tenderness during a period of one week. He was doing well until 4 years and 10 months after, when barium enema examination and colonoscopy incidentally demonstrated that the abdominal catheter had penetrated into the descending colon. However, he had no symptoms. He remained in good health during a period of observation. A year later he was readmitted to our department with an abscess of the abdominal wall. Plain radiograph of the abdomen demonstrated disconnection of the shunt catheter and it was thought that the abdominal catheter had been passed via the rectum. At operation a subcutaneous abscess was found and cultures grew proteus mirabilis. We discussed the mechanism of the developing of the abscess on the abdominal wall following penetration of the bowel. It is believed that abscess of the abdominal wall may occur due to spontaneous extraction of a previously inserted shunt catheter which has penetrated into the bowel.