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Numerous reports support evidence that dopaminergic mesolimbic pathways interact with opioid systems to influence the reinforcing properties of cocaine. Withdrawal from chronic administration of cocaine in rats causes an upregulation of mesocorticolimbic mu-opioid receptors during early stages, but information about prolonged cocaine abstinence is lacking. We addressed this issue by treating rats with cocaine or saline (control) intermittently (1 mg/kg, i.v., every 12 min for 2 h daily) for 10 days followed by a 10- or 20-day withdrawal period. The animals were then decapitated and the brains removed for quantitative in vitro autoradiographic analysis of 14 brain regions with 125I-DAMGO. A separate group of animals received two consecutive cycles of the 10-day cocaine/10-day withdrawal regimen. Only the group that participated in the two consecutive cycles showed a significant effect of treatment: downregulation of mu-opiate receptors in limbic cortical layer 3 (17% lower than saline-treated controls, P = 0.03), the core of the nucleus accumbens (16% decrease, P = 0.05), and the nucleus of the diagonal band (18% decrease, P = 0.05). The mu-receptor may manifest, as do other neural markers (e.g., dopamine transporter, dopamine efflux), a biphasic temporal pattern with upregulation during early phases of cocaine withdrawal but a downregulation at later times. Synapse 37:292–297, 2000. Published 2000 Wiley-Liss, Inc. more...

Excited states in {sup 182}Pt have been studied via the heavy-ion reactions {sup 170}Yb({sup 16}O,4n), {sup 162}Dy({sup 24}Mg,4n), and {sup 163}Dy({sup 24}Mg,5n). {gamma}-ray coincidence measurements were performed with arrays of HPGe detectors at the McMaster University Tandem Accelerator Laboratory ({sup 16}O-induced reaction) and the Institut de Physique Nucl{acute e}aire, Orsay ({sup 24}Mg-induced reactions). The ground-state rotational band has been extended to I=26{h_bar}, and six new band structures have been identified and assigned quasiparticle configurations. The {gamma}-vibrational band and the band built upon the first excited 0{sup +} state have also been extended. Properties of the rotational bands are compared with cranked-shell-model and total-Routhian-surface calculations. Evidence concerning shape coexistence at low spin and band crossings at high spin is discussed. {copyright} {ital 1997} {ital The American Physical Society} more...

Three superdeformed bands have been observed in the nucleus ${}^{144}$Eu with the GAMMASPHERE spectrometer in its early implementation phase. The reaction used was ${}^{122}$Sn${(}^{27}$Al,5${n)}^{144}$Eu at a beam energy of 142 MeV. All three bands are identified as single-neutron excitations with respect to ${}^{143}$Eu. One band is a confirmation of a previously suggested candidate. It is assigned as the yrast sequence based on the $\ensuremath{\pi}{6}^{1}\ensuremath{\nu}{7}^{1}$ configuration, and is believed to undergo an interaction with the $\ensuremath{\nu}$[514]9/2${}^{\ensuremath{-}}$ orbital. The other two bands are assigned as signature partners based on the $\ensuremath{\pi}{6}^{1}\ensuremath{\nu}{6\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}}^{1}$ configuration, where $6\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}$ corresponds to a mixed [651]1/2${}^{+}$/ [642]5/2${}^{+}$ state. The partner that contains the $\ensuremath{\alpha}$=-1/2 signature component of the $6\mathrm{\ifmmode \tilde{}\else \~{}\fi{}}$ orbital is identified from a band crossing that occurs in related bands in ${}^{145}$Gd and ${}^{146}$Gd. Alignment plots suggest that the interaction strength becomes stronger as the mass number increases. more...

Cocaine, as does exposure to other physiological stressors, releases brain corticotropin releasing factor (CRF), and this release habituates during the course of repeated cocaine administration in animals. Due to the many signs of anxiety and responses to stress that are produced by cocaine withdrawal in humans, the present study was designed to assess the effects of chronic cocaine and its withdrawal on regional 125I-Tyr-oCRF binding to the CRF1 receptor in brains of male Lewis rats. Cocaine or saline was intravenously infused for 10 days in a regimen that resembled a self-administration paradigm (1 mg/kg every 12 min for 2 h each day). Tissues were harvested either 15 min after or 10 days after the last cocaine infusion, and the brains were sectioned and prepared for CRF1 receptor autoradiography. Compared with findings in saline controls, there was a 31% lower level of CRF binding sites in the basolateral nucleus of the amygdala immediately after the last cocaine infusion, but not 10 days later. Neuroendocrine and non-neuroendocrine mechanisms associated with CRF1 receptors do not appear to contribute to long-term withdrawal effects. Synapse 25:272–276, 1997. © 1997 Wiley-Liss, Inc. more...

High-spin states in odd-odd 164 Lu have been studied using 19 F and 23 Na induced fusion-evaporation reactions. Three strongly coupled rotational bands have been established and three decoupled bands were tentatively assigned to 164 Lu. The band crossing frequencies, energy sig-nature splittings, and relative transition probabilities were deduced from experimental data and compared with neighboring even-even and odd- A nuclei. An anomalously large band crossing frequency was observed in the excited band, and a pronounced signature inversion was observed in the yrast band of 164 Lu. These anomalies may be associated with residual neutron-proton interactions. more...

A strong quasicontinuum ridge with a spacing of 58.1 {plus_minus} 0.3 keV was observed in {sup 173}Wand {sup 174}W when populated at high spin. The ridge is a factor of 4 times more intense than that of the sum of discrete bands over the same range of rotational frequencies. The strength of the ridge may be due to the large number of nearly degenerate proton orbitals lying above the {ital Z} = 73 gap occurring at a deformation {beta}{sub 2}{approx_equal}0.3. {copyright} {ital 1996 The American Physical Society.} more...

Precise level lifetimes have been measured for various superdeformed bands in Gd-148,Gd-149 and Dy-152 with the Doppler-shift attenuation method From the derived quadrupole moments, Q(0), we find large differences in deformation between the yrast bands and some excited bands in the gadolinium isotopes. Moreover, two of the excited Gd bands and the Dy-152 yrast band, which have identical moments of inertia, have different elongations, supporting the picture that alignment and deformation effects cancel in identical bands. more...

High-spin states in 107,108Pd and 109Ag have been studied by charged-particle-γ, γ-γ, and charged-particle-γ-γ coincidence measurements of heavy-ion fusion-evaporation reactions. The high-spin level schemes of these nuclides have been significantly extended and new deformed rotational bands have been found in each nuclide. These bands exhibit the general property of back bends corresponding to the rotational alignment of a pair of h11/2 quasineutrons. Band properties are compared with predictions of the cranked shell model and total Routhian surface calculations. The properties of the yrast and near-yrast bands of all three nuclides are generally consistent with predictions of moderate (β2 = 0.2) prolate deformation. more...

High-spin states have been studied in neutron-deficient $^{115}\mathrm{Xe}$ produced in the $^{60}\mathrm{Ni}$${(}^{58}$Ni,2pn\ensuremath{\gamma}) reaction. Transitions have been assigned to $^{115}\mathrm{Xe}$, for the first time, through their characteristic transition yields with respect to the total \ensuremath{\gamma}-ray sum energy and by systematic comparison to neighboring $^{113}\mathrm{Xe}$ and $^{117}\mathrm{Xe}$. \textcopyright{} 1996 The American Physical Society. more...

Lifetimes of {sup 160}Yb yrast states at high rotational frequencies have been measured by the Doppler broadened line shape technique. Excited states in {sup 160}Yb were populated by the reaction {sup 120}Sn({sup 44}Ca,4{ital n}){sup 160}Yb at a beam energy of 200 MeV and the experimental measurements were carried out in the coincidence mode with an array of Compton-suppressed germanium detectors. The results for the 24{sup +} to 32{sup +} yrast states led to values of the transition quadrupole moments similar to those obtained for the lower members ({h_bar}{omega}{le}0.29 MeV) of the ground band in previous recoil-distance measurements. The trend of reducing {ital Q}{sub {ital t}} values found for the {ital I}=34{sup +} and 36{sup +} states are suggestive of band termination. The results are discussed in the light of current theoretical predictions. {copyright} {ital 1996 The American Physical Society.} more...

From the observed competition between $M1$ and $E2$ $\ensuremath{\gamma}$ transitions deexciting the states of the two signature partner yrast superdeformed bands in $^{193}\mathrm{Tl}$, the ${i}_{\frac{13}{2}}$ ($\ensuremath{\Omega}=\frac{5}{2}$) intruder proton orbital is found to have $\frac{({g}_{K}\ensuremath{-}{g}_{R})K}{{Q}_{0}}=0.138\ifmmode\pm\else\textpm\fi{}0.008$. A model dependent value of ${g}_{s}^{\mathrm{eff}}=(0.7\ifmmode\pm\else\textpm\fi{}0.2){g}_{s}^{\mathrm{free}}$ is deduced. A saturation of the ${\mathcal{T}}^{2}$ moments of inertia, at rotational frequency $\ensuremath{\hbar}\ensuremath{\omega}g0.32$ MeV, is observed for the two bands. This feature is discussed in terms of exhausted quasineutron alignment in the presence of substantially reduced quasiproton alignment due to Pauli blocking. more...

We have previously shown that withdrawal from repeated, intermittent infusions of cocaine in Lewis rats results in a long-lasting reduction in dopamine transporter levels in the nucleus accumbens. The reduction is dose-dependent, requires multiple injections as well as about a 10-day withdrawal period. In this investigation, we show that the decrease (34%) occurs in the shell rather than in the core of the nucleus accumbens, and that a second cycle of cocaine administration and withdrawal has no additional effect. Also, there were no changes in transporter binding in the caudate putamen, the olfactory tubercle or the ventral tegmental area. These results indicate that the limbic portions of the nucleus accumbens are involved in neurochemical adaptations during withdrawal from cocaine. more...

A study of superdeformation in the nucleus $^{142}\mathrm{Sm}$ has revealed a superdeformed band, which is isospectral for \ensuremath{\gamma}-ray energies above \ensuremath{\sim}1 MeV with a $^{146}\mathrm{Gd}$ band. The relative alignment of these bands is compared to Hartree-Fock calculations. This second case of A\ensuremath{\sim}150 2p2n isospectrality is discussed in terms of specific orbitals which are often associated with identical bands. more...

A superdeformed band has been found in $^{142}\mathrm{Eu}$. It is populated with 1.2(2)% of the total \ensuremath{\gamma}-ray intensity that decayed into $^{142}\mathrm{Eu}$ via the reaction $^{120}\mathrm{Sn}$${(}^{27}$Al,5n${)}^{142}$Eu at 152 MeV. The strength of the band is similar to that previously reported in $^{143}\mathrm{Eu}$, where the superdeformed band is populated with an intensity of 1.1(1)%. This is unexpected, since both total Routhian surface (TRS) and cranked modified oscillator (MO) calculations predict that the superdeformed band in $^{143}\mathrm{Eu}$ becomes yrast at lower spin than that in $^{142}\mathrm{Eu}$. This difference is \ensuremath{\sim}4\ensuremath{\Elzxh} in the MO calculations and \ensuremath{\sim}8\ensuremath{\Elzxh} in the TRS. Extrapolation of the ``normal''-deformed yrast states in $^{143}\mathrm{Eu}$ shows, however, that a difference of \ensuremath{\sim}8\ensuremath{\Elzxh} in spin corresponds to a change in the relative energy of the superdeformed and normal-deformed yrast lines of only \ensuremath{\sim}1 MeV. more...

An enhanced-deformation (ED) rotational band with unusual characteristics has been discovered in the odd-Z nucleus $^{131}\mathrm{Pr}$. The dynamical moment of inertia ${\mathcal{J}}^{(2)}$=(50--60)${\mathrm{\ensuremath{\Elzxh}}}^{2}$ ${\mathrm{MeV}}^{\mathrm{\ensuremath{-}}1}$ and the extracted quadrupole moment ${\mathit{Q}}_{0}$ = 5.5 \ifmmode\pm\else\textpm\fi{} 0.8 eb (${\mathrm{\ensuremath{\beta}}}_{2}$=0.32\ifmmode\pm\else\textpm\fi{}0.05) are comparable with other ED bands (sometimes called ``superdeformed'') in the mass A\ensuremath{\sim}130 region. The two signature partners of the ED band are connected by dipole transitions which can be followed down to a K=9/2 bandhead. The nature of this band differs from all other ED bands in the A\ensuremath{\sim}130 region since the ${\mathit{i}}_{13/2}$ intruder neutron orbital is unoccupied. more...

A superdeformed band has been observed in the [ital N]=80 nucleus [sup 145]Tb which was produced with the reactions [sup 112]Sn([sup 37]Cl,2[ital p]2[ital n]) and [sup 118]Sn([sup 31]P,4[ital n]) at bombarding energies of 187 and 160 MeV, respectively. Since superdeformed bands also exist in the three lighter [ital N]=80 isotones [sup 142]Sm, [sup 143]Eu, and [sup 144]Gd, it is now possible to understand the valence-proton configurations of these bands in a systematic way. The T[sup (2)] dynamic moment of inertia in [sup 145]Tb shows no evidence for the [ital N] = 6 quasiproton crossing that is observed in [sup 144]Gd. Comparison with cranked Woods-Saxon and total Routhian surface calculations suggests that the proton configuration in [sup 145]Tb is 6[sup 1][direct product][404][sub 9/2[sup +]][sup 2] in which the quasiproton crossing is blocked. Furthermore, like [sup 143]Eu and [sup 142]Sm, there is no evidence in the T [sup (2)] for the [ital N]=6 quasineutron crossing predicted by the calculations. This may indicate that static neutron pairing correlations are quenched at the [ital N]=80 superdeformed shell closure. more...

States in the neutron-deficient $^{110,112}\mathrm{Te}$ isotopes have been populated following $^{58}\mathrm{Ni}$${+}^{58,60}$Ni reactions. Gamma-ray coincidence data were acquired with the Eurogam spectrometer in conjunction with the Daresbury recoil separator and with the Chalk River 8\ensuremath{\pi} spectrometer. Although the low lying yrast states are not collective in these nuclei, a long regular cascade of transitions, indicating collective behavior, was found in $^{112}\mathrm{Te}$ extending to high spin. This structure is interpreted in terms of a deformed 4-particle 2-hole ${0}_{2}^{+}$ state coupled to rotationally aligned quasiparticles, and represents the first example of a rotational ``intruder'' band in the tellurium isotopes. more...

Two weakly populated rotational bands have been established in [sup 106]Sn from the [sup 54]Fe ([sup 58]Ni,[alpha]2[ital p]) reaction at 243 MeV. One of the bands shows evidence of termination. The result is consistent with cranked Nilsson model calculations, which predict band terminations with a smooth and gradual shape change from a prolate collective to an oblate noncollective structure. more...

Three rotational bands have been discovered in the nucleus $^{109}\mathrm{Sb}$ that extend in angular momentum to \ensuremath{\simeq}81/2\ensuremath{\Elzxh}. The rotational frequency at the highest spins reaches \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\simeq}1.4 MeV, the highest frequency so far observed in a heavy nucleus. With increasing frequency the collective moments of inertia of all three bands smoothly diminish to unexpectedly low values, ${\mathit{scrJ}}^{(2)}$\ensuremath{\sim}13${\mathrm{\ensuremath{\Elzxh}}}^{2}$ ${\mathrm{MeV}}^{\mathrm{\ensuremath{-}}1}$, approximately one-third the rigid-body value, and, contrary to expectations, the moments of inertia become nearly equal to one another and to those of rotational bands in the core nucleus $^{108}\mathrm{Sn}$. more...

High spin states in the [sup 191]Tl nucleus have been populated via the [sup 159]Tb ([sup 36]S,4[ital n]) reaction at 165 MeV. Two weakly populated rotational bands have been observed with properties (energy spacings and dynamic moments of inertia) very similar to those of other superdeformed bands in the [ital A][similar to]190 region. The two bands can be interpreted as signature partners which exhibit some signature splitting for rotational frequencies [h bar][omega][ge]0.2 MeV. They are interpreted within the framework of cranked Woods-Saxon calculations as being based on the proton [ital i][sub 13/2]([Omega]=5/2) intruder orbital, in agreement with pairs of superdeformed bands seen in neighboring odd Tl nuclei. more...

A decay sequence above the I= 47 2 , 5.4 MeV level in 193Hg has been established through discrete γ-ray spectroscopy. The new energy levels exhibit single-particle character implying the dominant role of individual particle angular momentum alignment at moderate spins in the neutron-deficient Hg isotopes. more...

Lifetime measurements on the 5/2[sup +][402] band in [sup 173]Re have been carried out by the recoil-distance technique. Lifetimes of the stretched E2 transitions in both signatures of this band were measured up to a spin of 35/2[sup +] as were the lifetimes of most of the M1 transitions between the two signatures. Large deformation increases were found in both signatures at low rotational frequencies ([Dirac h][omega] [approx] 160 keV) as predicted by TRS calculations and, thus, offer new insight into the behavior of the 5/2[sup +][402] band in [sup 173]Re and perhaps into other light nuclei in this region. The B(M1) values also show an increase at about the same rotational frequency. Particle-rotor calculations can account qualitatively for the M1 and E2 transition rates at low spins, but the enhanced MI rates remain a puzzle. more...

New results have been obtained on superdeformed states in [sup 190]Hg, [sup 191]Tl, and [sup 192]Tl. For [sup 190]Hg, the previously identified superdeformed band has been extended up to a rotational frequency of [Dirac h][omega] [ge] 0.40 MeV by combining data from several different experiments. The extracted dynamical moment of inertia J([sup 2]) vs [Dirac h][omega] exhibits a distinct change in slope at [Dirac h][omega] = 0.32 MeV. For [sup 191]Tl and [sup 192]Tl, two and six superdeformed bands have been identified in these nuclei, respectively. Six of these eight bands exhibit a smooth rise in J([sup 2]) with [Dirac h][omega] characteristic of the other superdeformed bands identified in this mass region while the remaining two bands which are in [sup 192]Tl show a constant J([sup 2]) with [Dirac h][omega]. This new result can be understood in terms of Pauli blocking of quasiparticle alignments in high-N intruder orbitals. The new result for [sup 190]Hg is interpreted as evidence of a band interaction at the highest frequencies due to the rotational alignment of a pair of quasiparticles into these same intruder orbitals. These two new features taken together represent the first conclusive evidence that the alignment of intruders is responsible formore » the smooth rise in J([sup 2]) seen in the other superdeformed bands of this mass region.« less more...

Six superdeformed bands have been found in the nucleus {sup 192}Tl. For two of the bands, the dynamic moment of inertia {ital J}{sup (2)} is found to be constant with the rotational frequency {h bar}{omega}. This result can be understood in terms of Pauli blocking of quasiparticle alignments in intruder orbitals, and represents strong experimental evidence that the alignment of these intruders is responsible for the smooth rise in {ital J}{sup (2)} seen in other superdeformed nuclei of this mass region. more...

The nucleus 193Tl has been populated with the 160Gd(37Cl,4n) reaction and its level scheme has been extended up to spin 41 2 h by using an array of 12 Compton-suppressed Ge detectors. Near-oblate band structures arising from a 9 − 2 state and markedly different, single-particle-like, structures above a 13 + 2 state have been established. The two structures are consistent with total routhian surface calculations indicating the existence of two minima in the total routhian surface of the nucleus which survive separately up to the observed spins. Details of the rotational-like part are discussed in terms of the cranked shell model, while the single-particle-like features of the nucleus are compared with non-collective structures in neighboring nuclei, in particular 191Hg. more...

Using γ-γ correlation techniques, unresolved γ radiation associated with superdeformed (SD) excited states has been investigated for the nucleus 149 Gd populated via the 124 Sn( 30 Si, x n) reaction at 155 MeV bombarding energy. the intensity distrib ution has been measured as a function of rotational frequency. A “quasi-damped” region of excitation energy where the identity of individual SD bands melts is suggested by the relatively small value of the damping width Γ rot required by the fit to the experimental data. more...

High-spin states have been populated in odd-odd {sup 186,188}Au via the heavy-ion {sup 171,173}Yb({sup 19}F,4{ital n}) reactions at 93--94 MeV. Rotational bands built on 11{sup {minus}} oblate {nu}{ital i}{sub 13/2}{sup {minus}1}{direct product}{pi}{ital h}{sub 11/2}{sup {minus}1} structures have been observed in both nuclei, similar to those reported in {sup 190{minus}194}Au. Two new strongly coupled bands in {sup 186}Au are interpreted as prolate {pi}{ital h}{sub 9/2}{direct product}{nu}{ital i}{sub 13}2 and {pi}{ital i}{sub 13/2}{direct product}{nu}{ital i}{sub 13/2} configurations. Based on blocking arguments a band crossing in the latter structure is attributed to the alignment of {ital h}{sub 9/2} protons. Measured {ital B}({ital M}1;{ital I}{r arrow}{ital I}{minus}1)/{ital B}({ital E}2;{ital I}{r arrow}{ital I}{minus}2) ratios are compared to predictions of the Doenau and Frauendorf geometrical formalism extended to odd-odd cases. more...

The transitional nucleus $^{86}\mathrm{Zr}$ has been studied by the $^{60}\mathrm{Ni}$${(}^{30}$Si,2p2n) reaction, with \ensuremath{\gamma}-\ensuremath{\gamma} coincidence, angular correlation, Doppler-shift-attenuation and measurements. Band structures exhibiting strongly staggered M1 transition rates were found at high spins, with large B(M1) values but no significant E2 collectivity. The unusual behavior of this nucleus is interpreted within the framework of an interacting boson model incorporating two broken boson pairs. This new model for high-spin states is seen to be remarkably successful in describing the electromagnetic decay properties in the four-quasiparticle regime. more...

States of 126Ba up to spin 36+ were populated in the reaction 96Zr(34S, 4n)126Ba at 155 MeV and up to spin 20+ in the reaction 116Sn(13C, 3n)126Ba at 56 MeV. Gamma-ray spectroscopy was performed with the 8π spectrometer, an instrument comprising 20 Campton-suppressed HPGe detectors and 71 BGO ball elements. A level scheme organized into fifteen rotational bands is proposed on the basis on the γγ-coincidence and γ-ray angular correlation data. The competing π h 11 2 and v h 11 2 band crossings are investigated and interpreted in terms of cranked shell model and total routhian surface calculations. Amongst the topics discussed are (i) a comparison of DCO and spin orientation techniques for determining spins and multipolarities. (ii) the addivity property of quasiparticle energies or routhians, and (iii) analysis of B(M1)/B(E2, ratios between signature partner bands. The possibility of couplings between vibrational and aligned quasiparticle structures is explored. more...

Two excited superdeformed bands in $^{149}\mathrm{Gd}$ have been observed in \ensuremath{\gamma}-ray spectroscopy. Based on the behavior of the dynamical moments of inertia, we assign one band to a neutron excitation and the other to a proton excitation. The proton-excited-band \ensuremath{\gamma}-ray energies are nearly identical to those already known in $^{150}\mathrm{Tb}$. In addition, two new members of the $^{149}\mathrm{Gd}$ yrast cascade have been observed, extending the band to spin 135/2\ensuremath{\Elzxh}. The results are discussed in terms of high-N intruder orbitals in the cranked-shell model. more...

High-spin states in 124 Ba were populated via the 94 Zr( 34 S, 4n) 124 Ba and 110 Cd( 16 O, 2n) 124 Ba reactions at 145 MeV and 60 MeV, respectively. The yrast band has been extended to 34 ħ and seven side bands have been observed. Gamma-ray angular distributions with respect to the nuclear spin axis have been used along with directional correlation (DCO) ratios to establish spins and multipolarities. The competing π h 11 2 and ν h 11 2 crossings in this region are investigated and an interpretation of the observed crossings is proposed within the framework of the cranked shell model (CSM) and total routhian surface (TRS) calculations. more...

High-spin states in the transitional nucleus 184Pt were populated via the reactions 154Sm(34S, 4n)184Pt and 172Yb(16O, 4n)184Pt. The yrast band was extended up to I = 28 ħ and six new side bands built on both neutron and proton quasiparticle configurations were observed. Shell correction-type calculations indicate variations of the nuclear shape in different bands, especially as a result of band crossings due to the process of angular momentum alignment. Comparison of the band characteristics are made between 184Pt and eight adjacent nuclei. The pattern of band crossings in these nine nuclei is considered from the viewpoint of blocking comparisons and of theoretical calculations. The competition between low-frequency vi 13 2 and πh 9 2 band crossings is discussed. more...

Excited states in {sup 113}In were populated via the reactions {sup 100}Mo({sup 18}O,p4n){sup 113}In and {sup 110}Pd({sup 7}Li,4n){sup 113}In. The two known {delta}J=2 intruder bands, based on the {pi}g{sub 7/2}xd{sub 5/2} and {pi}h{sub 11/2} orbitals, have been extended by 8({Dirac_h}/2{pi}) to spins (49/2{sup +})({Dirac_h}/2{pi}) and (55/2{sup -})({Dirac_h}/2{pi}), respectively. The previous finding of three sequences of {delta}J=1 {gamma}-ray transitions has been confirmed. A self-consistent cranked shell-model calculation gives a good description of the contrasting alignment patterns of the two {delta}J=2 intruder bands. The intruder bands, the known sequences of M1 transitions, and spherical levels together represent a coexistence of three different excitation modes in this nucleus. more...

High-spin states have been identified in doubly odd $^{114}\mathrm{I}$ produced in the $^{60}\mathrm{Ni}$${(}^{58}$Ni,3pn\ensuremath{\gamma}) reaction. Two rotational band structures have been observed. One band exhibits no signature splitting, while the second exhibits a large signature splitting. These bands are interpreted in terms of \ensuremath{\pi}${\mathit{g}}_{9/2}$\ensuremath{\bigotimes}\ensuremath{\nu}${\mathit{h}}_{11/2}$ and \ensuremath{\pi}${\mathit{g}}_{7/2}$\ensuremath{\bigotimes}\ensuremath{\nu}${\mathit{h}}_{11/2}$ quasiparticle configurations, respectively. more...

States in neutron-deficient $^{110}\mathrm{Te}$ have been studied with the $^{58}\mathrm{Ni}$${+}^{58}$Ni reaction at 250 MeV. An unusual feature is that, above spin ${8}^{+}$, negative parity states become yrast. These states are interpreted in terms of a \ensuremath{\nu}[${\mathit{h}}_{11/2}$\ensuremath{\bigotimes}${\mathit{d}}_{5/2}$] structure (\ensuremath{\Delta}l=\ensuremath{\Delta}j=3). For spins above ${15}^{\mathrm{\ensuremath{-}}}$, strong (E1) dipoles are seen linking another band into the negative-parity states. This is taken as evidence for octupole correlations in $^{110}\mathrm{Te}$ at high spin. more...

Numerous reports support evidence that dopaminergic mesolimbic pathways interact with opioid systems to influence the reinforcing properties of cocaine. Withdrawal from chronic administration of cocaine in rats causes an upregulation of mesocorticolimbic mu-opioid receptors during early stages, but information about prolonged cocaine abstinence is lacking. We addressed this issue by treating rats with cocaine or saline (control) intermittently (1 mg/kg, i.v., every 12 min for 2 h daily) for 10 days followed by a 10- or 20-day withdrawal period. The animals were then decapitated and the brains removed for quantitative in vitro autoradiographic analysis of 14 brain regions with (125)I-DAMGO. A separate group of animals received two consecutive cycles of the 10-day cocaine/10-day withdrawal regimen. Only the group that participated in the two consecutive cycles showed a significant effect of treatment: downregulation of mu-opiate receptors in limbic cortical layer 3 (17% lower than saline-treated controls, P = 0.03), the core of the nucleus accumbens (16% decrease, P = 0.05), and the nucleus of the diagonal band (18% decrease, P = 0.05). The mu-receptor may manifest, as do other neural markers (e.g., dopamine transporter, dopamine efflux), a biphasic temporal pattern with upregulation during early phases of cocaine withdrawal but a downregulation at later times. more...

Neural circuits comprised of dopamine-containing and dopamine-receptive neurons are altered functionally after the repeated intermittent administration of cocaine and its withdrawal. The characterization of these neuroadaptive changes at various times after repeated exposure to cocaine is important because they may relate to addictive or withdrawal states associated with cocaine abuse. They also may suggest targets leading to the development of medications to treat one or more aspects of cocaine dependence. more...

Cocaine, as does exposure to other physiological stressors, releases brain corticotropin releasing factor (CRF), and this release habituates during the course of repeated cocaine administration in animals. Due to the many signs of anxiety and responses to stress that are produced by cocaine withdrawal in humans, the present study was designed to assess the effects of chronic cocaine and its withdrawal on regional 125I-Tyr-oCRF binding to the CRF1 receptor in brains of male Lewis rats. Cocaine or saline was intravenously infused for 10 days in a regimen that resembled a self-administration paradigm (1 mg/kg every 12 min for 2 h each day). Tissues were harvested either 15 min after or 10 days after the last cocaine infusion, and the brains were sectioned and prepared for CRF1 receptor autoradiography. Compared with findings in saline controls, there was a 31% lower level of CRF binding sites in the basolateral nucleus of the amygdala immediately after the last cocaine infusion, but not 10 days later. Neuroendocrine and non-neuroendocrine mechanisms associated with CRF1 receptors do not appear to contribute to long-term withdrawal effects. more...

Cocaine withdrawal in animals causes a transient increase followed by a long-lasting decrease in mesolimbic dopamine transporters, dopamine efflux and the number of dopamine cells firing spontaneously. Other changes in the nucleus accumbens and frontal cortex also suggest alterations in dopamine-receptive neurones and circuits. In humans, brain imaging has provided evidence for some similar, long-lasting changes in dopaminergic neurones and innervated areas. These results suggest a protracted biochemical abstinence syndrome for cocaine. In this review, Michael Kuhar and Nancy Pilotte focus on biochemical changes that occur following withdrawal from repeated cocaine administration. A key question for treatment is whether (some of) these persistent changes underlie withdrawal symptomatology such as anhedonia and relapse. more...

We have previously shown that withdrawal from repeated, intermittent infusions of cocaine in Lewis rats results in a long-lasting reduction in dopamine transporter levels in the nucleus accumbens. The reduction is dose-dependent, requires multiple injections as well as about a 10-day withdrawal period. In this investigation, we show that the decrease (34%) occurs in the shell rather than in the core of the nucleus accumbens, and that a second cycle of cocaine administration and withdrawal has no additional effect. Also, there were no changes in transporter binding in the caudate putamen, the olfactory tubercle or the ventral tegmental area. These results indicate that the limbic portions of the nucleus accumbens are involved in neurochemical adaptations during withdrawal from cocaine. more...

A thick foil of 238 U was bombarded with 209 Bi beams at 1130 and 1330 MeV, delivered by the TASCC facility at Chalk River Laboratories. Gamma-ray spectroscopy of states populated in multiple Coulomb excitation was performed with the 8π spectrometer, an instrument comprising 20 Compton-suppressed HPGe detectors and 71 BGO ball elements. The event trigger required that 3 BGO elements and 2 HPGe detectors fire in coincidence. The experiment achieved a high degree of sensitivity, the weakest rotational band observed had about 0.16% intensity of the ground state rotational band. Several bands were observed to high spin for the first time, including the γ-vibrational band (spin 27 + ) and the octupole bands with K = 0 (spin 31 − ), K = 1 (spin 28 − ) and K = 2 (spin 25 − ). Results for positive and negative parity vibrational bands are compared with cranked RPA calculations. Although this theory can explain some features of the data, many puzzling aspects remain to be explored. more...

Male, Lewis rats were administered cocaine or saline i.v. in an intermittent fashion for 5, 10 or 20 days and killed at various times afterwards. Dopamine transporter binding was then measured in dorsal striatum and nucleus accumbens. Transporter binding was not changed in dorsal striatum under any conditions tested. In the nucleus accumbens, however, binding was decreased in animals given cocaine (10 mg/kg total) for 10 days and withdrawn for 10, 30 or 60 days, but not in animals withdrawn for 0, 1, 3 and 6 days. There were no changes in animals given cocaine for 5 days and withdrawn for 10, or in animals given drug for 20 days and withdrawn for 1 day. Animals given only 1/10 of the cocaine dose had no changes in nucleus accumbens after 10 days of administration and 10 days of withdrawal. Scatchard analysis in control animals indicated that there were significant differences in both Kd and Bmax when comparing nucleus accumbens with dorsal striatum. Within the nucleus accumbens, decreases in binding after a cessation of cocaine administration were associated with a change in Bmax and not in Kd. These data indicate that long-lasting changes in the mesolimbic dopaminergic system can occur during the withdrawal period, and may contribute to behavioral effects during this period. more...

High-spin states in [sup 109,111]Cd have been investigated with the reaction [sup 96]Zr([sup 18]O,[ital xn])[sup 114[minus][ital x]]Cd at beam energies of 60 and 70 MeV. The decoupled yrast bands observed in both nuclei are interpreted as being built upon a low-[ital Kh]11/2-quasineutron configuration. Both structures exhibit band crossings corresponding to the rotational alignment of a pair of [ital h]11/2 quasineutrons. Two positive-parity bands built on a [ital g]7/2-quasineutron configuration are observed in [sup 109]Cd. These exhibit a signature inversion in the region of the first ([nu][ital h][sub 11/2)][sup 2] alignment. This may be associated with some softness to triaxiality. The results are discussed in terms of the cranked shell model, total Routhian surface calculations, and the systematics of neighboring nuclei. more...

Male, Lewis rats were treated intravenously for 2 weeks with saline or cocaine using a dose and injection schedule that is similar to the doses and patterns of cocaine intake in self-administration studies. Ten days after cessation of treatment, dopamine transporter binding levels were decreased in the nucleus accumbens but not in the striatum. In situ hybridization studies revealed decreases in dopamine transporter mRNA that were restricted to cells of the interfascicular and caudal linear nuclei; these dopaminergic cell groups, found in the ventral tegmentum, project to the nucleus accumbens and other limbic areas. Other dopaminergic cell groups in midbrain which project mainly to other areas did not show a decrease in mRNA. These results indicate that gene expression can be altered many days after withdrawal from cocaine, and provide an example of transporter regulation by a change in gene expression. more...

Rotational bands of 157 Ho have been populated via the 124 Sn( 37 Cl, 4n) reaction at beam energies of 155 and 165 MeV. Gamma-ray spectroscopy was performed using the 8 π spectrometer at Chalk River. Many rotational bands have been observed for the first time. A detailed level scheme is presented, containing approximately 380 transitions, and the quasiparticle structure of the various bands is discussed. Band termination has been observed in the yrast states. For strongly coupled bands, B (M1)/ B (E2) transition strength ratios are extracted and compared with previous measurements and theoretical expectations. Branching ratios for out-of-band E2 transitions are analysed to extract band mixing interaction strengths. Implications for rotational damping are considered. The interaction at the first backbend in the ground band is found to be strongly signature dependent; this is evidence for a signature-dependent triaxial shape of the nucleus. more...

The in vitro autoradiographic distribution of desipramine-insensitive specific [3H]mazindol binding sites (labelling the dopamine transporter) was determined in brain sections from rats receiving repeated i.v. infusions of saline or cocaine (1 mg/kg, every 12 min for 2 h/day), for 10 days. Brains were removed either within 15 min of or 10 days after the last treatment. A marked dorsal-to-ventral gradient in [3H]mazindol binding appeared in the striatum with the dorsal caudate putamen showing the greatest binding and the medial shell of the nucleus accumbens the least. Cocaine-associated changes in [3H]mazindol-labelled dopamine uptake sites occurred only in the nucleus accumbens (57 and 66% decrease in the lateral core and medial shell, respectively), of animals 10 days after the last treatment. Down-regulation of the dopamine transporter in the nucleus accumbens by withdrawal of chronic cocaine may be one of the mechanisms involved in cocaine's long-term abstinence effects. more...