PubMed · 2667743
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C J Witkop. Albinism.. https://doi.org/10.1016/0738-081x(89)90059-x
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To address the existence of possible functional interactions between delta- and mu- receptors in relation to the affective component of pain, we have studied the effects of functional blockade of delta-receptors by a chronic treatment with naltrindole (1 mg/kg, 8 consecutive days) on antinociceptive responses to morphine (2 and 5 mg/kg) in the tail electric stimulation test, in adult male rats. The thresholds for the motor response (tail withdrawal), vocalization during stimulus and vocalization afterdischarge were assessed. These responses are considered to be integrated at spinal, medulla oblongata and diencephalon-rhinencephalon levels, respectively. The results show that the vocalization during stimulus and the vocalization afterdischarge were significantly affected by morphine in a dose dependent manner, the latter response being the most sensitive to the effects of the mu-opioid agonist. However, no significant effect was observed on motor responses at the doses used in this study. Chronic naltrindole treatment did not modify the inhibitory effect of morphine on the vocalization responses. Since the vocalization afterdischarge is related to the affective component of pain, the data suggest that the delta-opioid receptor is not involved in the supraspinal mechanisms at which these responses are organized and that there is not a mu-delta interaction in the modulation of the affective responses to noxious electrical stimulation.
The fate of calbindin D28k (calbindin)-labeled horizontal cells in the ischemic rat retina induced by increasing intraocular pressure was investigated by immunocytochemistry using an antiserum against calbindin. In the normal retina, strong calbindin-like immunoreactivity was seen in the horizontal cells, and the density of the labelled horizontal cells was 815.3+/-15.2 per mm2. The thickness of the treated retina became progressively thinner with increasing reperfusion time after the ischemic insult due to a loss of retinal cells in the inner and outer nuclear layers. However, the densities of the horizontal cells per mm2 were 814.0+/-26.4 at 1 week, 813.3+/-20.8 at 2 weeks, and 812.6+/-11.5 at 4 weeks, indicating that horizontal cells did not degenerate during experimental periods. Thus, calbindin may have a protective role for horizontal cells to ischemic insult by its ability to buffer calcium influx in the rat retina.
The albino deletions identify at least seven functional intervals essential for pre- and postnatal development in the 6- to 10-cM region surrounding the albino coat color (c = tyrosinase) locus on mouse chromosome 7. The c112K deletion identifies a putative thymus functional region not removed by the overlapping c3H deletion. Cloning the c3H proximal breakpoint provided a starting point for construction of an 840-kb BAC contig spanning the c112K and c3H (D7Ssb3Hp) proximal breakpoints. These breakpoints are separated by 320-350 kb. The aryl hydrocarbon receptor nuclear translocator-2 (Arnt2) is completely removed by the c112K deletion and spans 130-170 kb of the interval. Although Arnt2 is a candidate for the thymus defects in c112K homozygotes, the possibility that other as yet unidentified genes in the c112K deletion are responsible for the abnormalities has not been ruled out. Arnt2 is a member of the bHLH-PAS (Per, Ahr, Arnt, Sim) family of transcription factors and shares the highest similarity with Arnt. The survival of c112K homozygotes markedly contrasts the embryonic lethality observed in Arnt-deficient embryos and suggests distinct roles for these related transcription factors during embryogenesis.