Search PubMed⌕ Search

Biomedical subjects

J D Valentine

Publications and source records attributed to J D Valentine.

10 recordsLinked to original sources
PubMed1991

Opioid modulation of pavlovian learning in rabbits: involvement of sublenticular pathways.

Intravenous naloxone enhanced, and D-Ala2-Met-enkephalinamide (DALA) impaired, Pavlovian conditioned heart rate discrimination in rabbits (Oryctolagus cuniculus) during initial training trials, compared with saline; naloxone also delayed subsequent extinction of the discrimination. These effects of the opioid treatments on discrimination were abolished by parasagittal knife-cut lesions in the sublenticular substantia innominata that did not, themselves, impair discrimination. Both naloxone and DALA decreased the magnitude and altered the topography of bradycardiac conditioned responses, and the lesions also abolished these effects of the opioid treatments, but they did not alter the effect of naloxone to decrease bradycardiac orienting response magnitude. These findings suggest that fibers in the sublenticular area mediate specifically the effects of systemic opioids on associative functions during Pavlovian cardiac conditioning and extinction.

Animals↗
PubMed1989

Enhancement of pavlovian conditioned suppression by mild ethanol intoxication.

Rats were trained to bar-press for food and then received aversive Pavlovian conditioning following low doses of ethanol (0-1600 mg/kg in different groups). They were tested for Pavlovian conditioned suppression of bar-pressing 48 h, 7 days, and 14 days later following no additional differential treatments. The results showed that very low doses of ethanol (approximately 200 mg/kg) during training enhanced later conditioned suppression, whereas more moderate doses (800-1600 mg/kg) disrupted Pavlovian conditioning. These results parallel earlier observations that very low ethanol doses enhance Pavlovian conditioned eyeblink and heart rate responses in rabbits, and suggest that facilitation of Pavlovian conditioning may be a general effect of mild ethanol intoxication.

Alcoholic Intoxication↗
PubMed1989

Light and electron microscopic evaluation of Proplast II TMJ disc implants.

Proplast II disc implants (Vitek Inc, Houston) were used in nine patients (14 joints) who underwent discectomy of the temporomandibular joint (TMJ). These patients subsequently underwent removal of the implants from 10 to 28 months postplacement due to pain and occlusal changes or radiographic changes in the joints. Light and electron microscopic evaluations were performed on the retrieved implants and surrounding tissue. Evidence of gross deterioration manifested by fracture of the implant was present in 10 of the 14 implants, and microscopic evidence of deterioration was present in all implants. Foreign-body giant cell reaction in surrounding tissues and microfragmentation of the implant were evident in all joints.

Adult↗
PubMed1986

Ethanol enhancement of Pavlovian conditioning.

Rabbits were tested for Pavlovian conditioning and extinction of eye blink and heart rate responses, following water or various doses of ethanol (375-1,500 mg/kg, po). The highest dose suppressed both eye blink and heart rate conditioning during training, whereas the lowest dose enhanced heart rate responses during training and increased eye blink responses during later extinction in a symmetrically state-dependent manner. An intermediate dose (750 mg/kg) administered during training enhanced heart rate responses and suppressed eye blink responses but increased eye blink responses during later extinction following either ethanol or water. Ethanol treatments also suppressed unconditioned responses to shock and increased locomotor activity in rabbits; however, these effects differed qualitatively from those that occurred during Pavlovian training and extinction. These results suggest that very low doses of ethanol can enhance the ability of stimuli to elicit Pavlovian conditioned reflexes and impair the ability to adaptively modify these reflexes when stimulus contingencies later change.

Animals↗
PubMed1983

Benzodiazepine receptor mediated discriminative cues: effects of GABA-ergic drugs and inverse agonists.

Rats were exposed to a two-lever drug discrimination procedure using the benzodiazepine (BZ) receptor inverse agonists N'-methyl-beta-carboline-3-carboxamide (FG 7142) or methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). FG 7142 (30 mg/kg) failed to acquire discriminative stimulus control, although it did suppress responding. The same group of animals was trained successfully to discriminate diazepam (DZP, 2.5 mg/kg) from vehicle. The DZP cue was potentiated by the GABA agonist 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridin-3-ol (THIP, 1,3 mg/kg); THIP alone produced vehicle-appropriate responding. In addition, clonazepam (0.2 mg/kg) and chlordiazepoxide (5 mg/kg) substituted for DZP (with potencies of 7.5 and 0.25 times that of DZP, respectively). In antagonism tests, FG 7142 (5-17.5 mg/kg), methyl-beta-carboline-3-carboxylate (beta-CCM, 2.5 mg/kg) did not effect, bicuculline (2 mg/kg) and DMCM (1 mg/kg) partially blocked, and the BZ receptor antagonist Ro 15-1788 (40 mg/kg) completely blocked the discriminative stimulus effects of DZP. In animals trained to discriminate DMCM (0.2 mg/kg) from vehicle, 95.2% substitution occurred with bicuculline (2 mg/kg); DZP (1-5 mg/kg) completely antagonized DMCM. These results indicate that the DZP cue is mediated by GABA-coupled BZ receptors and that GABA may modulate the efficacy of a BZ at its receptor site. However, since inverse BZ receptor agonists (FG 7142, DMCM and beta-CCM) were, at best, only marginally effective in antagonizing DZP, the DZP cue may be mediated by a distinct subclass of BZ receptors.

Animals↗
PubMedDate not supplied

Concomitant Pavlovian conditioning of heart rate and leg flexion responses in the rat.

Pavlovian conditioning was studied in male Fischer 344 rats using tones as the conditioned stimulus (CS) and footshock as the unconditioned stimulus (UCS). Different groups of animals received (a) contiguous CS-UCS pairings with a 0.5 sec CS, (b) contiguous CS-UCS pairings with a 4.0 sec CS, or (c) a random sequence of noncontiguous tones and shocks using either a 0.5 sec or a 4.0 sec CS. Heart rate (HR) and leg flexion (LF) responses were recorded. Leg flexion conditioning occurred only in the 0.5 sec contiguous group. Decelerative HR CRs occurred only in the 4.0 sec contiguous group. Accelerative HR changes occurred in the other two groups but were significantly greater in the 0.5 sec contiguous group. These results are similar to but not identical to those obtained during eyeblink or nictitating membrane conditioning in rabbits, and suggest that the topography of the Pavlovian HR CR is dependent on the simultaneous occurrence of other classically conditioned responses.

Animals↗
PubMedDate not supplied

Some determinants of attrition in prospective studies on aging.

Demographic measures, psychosocial variables, and objective and subjective measures of physical impairment were assessed in elderly men twice at intervals of 12 to 18 months. Canonical discriminant function analysis of the relationship between these predictor variables on the first testing and whether participants (a) returned for retesting, (b) did not return because of apparent disinterest, or (c) did not return because of illness or death, revealed two significant canonical variates. The first, characterized by decreased mental and physical capacity, discriminated between the deceased/ill group and the other two groups. The second was characterized by decreased social interaction and life satisfaction, and increased life events, and distinguished between the disinterested group and the other two groups. However, both groups that failed to return for retesting showed evidence of impaired physical health and a general disengagement from social and personal activities, compared to the retested group.

Adaptation, Psychological↗