Long-term memory for DRL: a comparison between weanling, adult and senescent rats

Weanling (24-day-old), adult (3- and 7-month-old) and senescent rats (24-month-old) were submitted for 10 days to a DRL 20 seconds schedule, at a pace of 4 sessions a day. After a 3 month interval, the subjects were tested for retention in an identical experimental setting. In training, the median Interresponse-Time (IRT) is directly related to the age of the subjects, whereas response rates are inversely related to it. Age-related differences subside at the end of training. In testing, adult rats improve their efficiency, whereas senescent and particularly former weanling rats do not catch up with training scores. These data are discussed in relationship with developmental variables in the temporal regulation of behavior, collateral activity, contextual and methodological variables in the study of memory.     

Septal damage during the maturation of inhibitory responding: effects in juvenile and adult rats

Septal lesions were inflicted in young rats either during or after the maturation of inhibitory responding. When tested as juveniles (Day 25) or as adults, septal-operates were significantly different from controls on 2-way active avoidance and habituation responding, regardless of the age at which the lesion was produced. These data are in contrast with others showing that damage to subcortical structures can result in sparing of certain behavioral functions. The difference between functional sparing and functional disruption may be due to different patterns of brain projection pathways established after early lesions are produced. Neurochemical supersensitivity may also be a differentiating factor.     

Muscarinic receptor expression and receptor-mediated detrusor contraction: comparison of juvenile and adult porcine tissue

Urinary bladder function is known to mature during fetal and postnatal development, including changes in neurotransmitter regulation of detrusor contraction. However, only few experimental data are available about muscarinic receptor antagonist function in the urinary bladder from young animals. In the present study, we compare the muscarinic receptor-mediated contractions in juvenile and adult porcine detrusor and the effects of antimuscarinic compounds. Urinary bladders from young (8–12 weeks; 12- to 35-kg body weight) and mature pigs (>40 weeks; >100 kg) were compared. Muscarinic receptor expression was assessed by real time polymerase chain reaction and radioligand binding. Muscle contraction was measured with a force transducer; L-type Ca²⁺ currents (I _Ca,L) of isolated detrusor myocytes were recorded with standard voltage clamp technique. Juvenile and adult detrusor expressed similar quantities of the messenger RNA of M₂ and M₃ receptors. The number of [³H]QNB-binding sites and their affinity for the radioligand were also similar between juvenile and adult detrusor. In contrast, maximum contractile responses to the muscarinic receptor agonist carbachol were slightly larger in juvenile than adult bladders. On the other hand, carbachol was slightly less potent in juvenile than in adult tissue. The M₃ antagonist DAU 5884 and the spasmolytic drug propiverine inhibited contractile responses with comparable efficacies and potencies in juvenile and adult tissue. I _Ca,L was somewhat smaller in juvenile than in adult cells. Taken together, these data suggest that expression and function of M₂ and M₃ receptors are similar in the detrusor of juvenile and mature pigs. Therefore, similar responses to antimuscarinic compounds could be expected in young and adult patients.     

Cognitive and noncognitive processes involved in selective object exploration: comparison between young adult and old rats.

The age effects on locomotor activity, object-oriented exploration, habituation, and response to a spatial change were studied in young adult and old rats using an object exploration test. In this test the spatial response was evaluated by the renewal of exploration of a familiar object after its repositioning. The specificity of the spatial response was determined by comparison with control animals not submitted to a spatial change. Male Wistar rats 6 and 24 months old were used. Results showed a significant decrement in locomotor activity, object exploration, and spatial reactivity in old rats. The habituation curve and the reactivity to a new object were preserved. Detail analyses suggest that the spatial deficit of old rats is due to an incapacity to detect the spatial change and not to their poor locomotor or exploratory activity. These results corroborate those obtained in spatial orientation tasks and support the idea that the lack of spatial response observed in old animals is more related to cognitive impairments than to other factors such as sensory, motor, or motivational differences.     

Different physiological properties of spontaneous excitatory postsynaptic currents in nucleus accumbens shell neurons between adult and juvenile rats

Studies have demonstrated the changes of the physiological characteristics of nucleus accumbens (NAc) neurons with the postnatal development of rats. In the present study, spontaneous excitatory postsynaptic currents (sEPSCs) were recorded in the slices of NAc shell (NAcS) of adult and juvenile rats. Our results demonstrate that both the average amplitude of sEPSCs and the average frequency of sEPSCs in the NAcS slices of adult rats decreased significantly than that in juvenile rats. The average half width of sEPSCs in the NAcS slices in adult rats increased significantly than that in juvenile rats. The rise time of sEPSCs, the rise 50 time of sEPSCs and the 10–90 rise time of sEPSCs in the NAcS slices increased significantly in adult rats than that in juvenile rats. The decay time of sEPSCs in the NAcS slices also increased significantly in adult rats than that in juvenile rats. The above results strongly indicate that there are marked changes in the electrophysiological properties of single sEPSC in the NAcS slices of juvenile and adult rats.     

Prolactin levels in juvenile and adult rats following acute restraint and the open field

Acute restraint and exposure to a novel environment alter behavior and increase prolactin levels in rats quickly and reliably. However, little research is available that examines behavior and levels of prolactin as a result of acute exposure to one stressor immediately followed by a second stressor. Similarly, a relationship between prolactin and behavior has not been established. In the present study, juvenile (35-day-old) and adult (5-month-old) rats were either placed in a novel open field for 10 min or restrained for 10 min prior to exposure to the open field. Restrained juveniles groomed more than control juveniles and restrained adults. Conversely, restraint + open field reduced ambulation and rearing among juvenile males and females, and adult females ambulated less than control females and restrained males across both behaviors. In addition, results from the present study demonstrated the first reported relationship between prolactin and open-field behaviors. Prolactin was positively correlated with rearing and number of fecal boli, and levels were negatively correlated with freezing. Among adult females, prolactin levels were lower following restraint + open field than after exposure only to the open field. This may be explained by the psychological response to the open field when it directly followed the physical stressor of acute restraint.     

Association between testicular dysgenesis syndrome (TDS) and testicular neoplasia: evidence from 20 adult patients with signs of maldevelopment of the testis

Based on a well established association between testicular cancer and undescended testis and more recent publications on epidemiological links between these disorders and male infertility, we proposed the existence of a testicular dysgenesis syndrome (TDS). In most cases TDS presents with impaired spermatogenesis, only in rare cases the full range of its signs, including genital malformations and testicular cancer can be seen in one patient. In order to further corroborate our hypothesis about the presence of testicular dysgenesis in patients with testicular abnormalities, we decided to re-analyse recent testicular biopsies derived from patients with infertility, hypospadias and undescended testis. We searched for histological signs of testicular dysgenesis: microliths, Sertoli-cell-only tubules, immature seminiferous tubules with undifferentiated Sertoli cells, and tubules containing carcinoma in situ (CIS) cells. We identified 20 patients who fulfilled the histological criteria for testicular dysgenesis, 9 of whom were diagnosed with uni- or bilateral testicular germ cell neoplasia, and the remaining ones with subfertility. The presence of CIS was detected in 5 patients (3 of them with overt contralateral germ cell tumours). In all but one of the CIS cases, at least one additional sign of testicular dysgenesis was detected. Clinical records of all patients were subsequently analysed. The majority of cases had oligozoospermia or azoospermia. Their reproductive hormone profiles correlated with the results of semen sampling and testicular histology. In conclusion, our study of 20 patients with various reproductive abnormalities provided evidence that TDS is a real clinical entity. We speculate that most of these abnormalities are caused by adverse environmental effects rather than specific gene mutations.     

Abnormal branch of the testicular artery

We present a case report of an abnormal course and branching of the right testicular artery, which was uncovered during routine dissection of the abdomen in our first year medical class. It arose from the anterior surface of the abdominal aorta and immediately divided into two branches; one branch coursed inferiorly behind the inferior vena cava as the testicular artery proper, while the other branch passed behind the inferior vena cava and emerged on the anterior surface of the right kidney. After crossing the anterior surface of the kidney, it bifurcated into an ascending branch that went to the right suprarenal gland and a descending branch that ended in the posterior abdominal wall. The left testicular artery was normal in its course and distribution. This is a very rare variation.     

Differences in intermediary energy metabolism between juvenile and adult Fasciola hepatica

A comparison of glucose catabolism by juvenile and adult liver flukes, Fasciola hepatica, showed that in the adult the cytosolic degradation of glucose via phosphoenolpyruvate carboxykinase (PEPCK) was the most important route, whereas in the freshly excysted juvenile a large part was degraded via pyruvate kinase (PK). However, it was also shown that the adult did not exclusively use the PEPCK pathway, nor did the juvenile exclusively use the PK pathway. When the juvenile was forced to anaerobic functioning it produced propionate and acetate just like the adult, but this did not imply that it switched to the pathways of the adult: the pathway via PK remained important. Malic enzyme (NADP(H)-dependent) was demonstrated to be present in the cytosol and in the mitochondria of both juveniles and adults. These enzyme activities enable the parasite to use a mixture of malate and pyruvate in any ratio as substrate for the mitochondrial production of propionate and acetate. Pyruvate dismutation was important in the anaerobically functioning juvenile, whereas in the adult malate was the major, but not the only mitochondrial substrate. The pH profiles of PK and PEPCK showed that the pathway of PEP metabolism at the PK/PEPCK branchpoint can be regulated by the pH. However, the end products of glucose breakdown were not dependent on the pH. During its development, the liver fluke will gradually be forced to anaerobic functioning. At first, the acidic end product will favour a partitioning of PEP at the PK/PEPCK branchpoint towards malate formation. Later, a lasting predominance of the PEPCK pathway occurs as PK activity almost completely disappears.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrophysiological differences in the CpG aerial respiratory behavior between juvenile and adult Lymnaea

Intact, freely moving juvenile Lymnaea perform aerial respiration significantly less often than do adults. We therefore hypothesized that RPeD1, the central pattern generator (CPG) neuron that initiates rhythmogenesis, would be less active in juveniles than adults. Using both isolated and semi-intact preparations to directly test this hypothesis, we found the opposite; juvenile RPeD1s were significantly smaller and more excitable than RPeD1s from adults. Significant age-related differences were found in the membrane resistance (greater in juveniles), time constant (smaller in juveniles), and rheobase current (lower in juveniles), all of which would tend to make juvenile cells significantly more excitable. However, there were significant age-related differences in the synaptic connectivity within the CPG and in peripheral input to the CPG, all which favor more rhythmic activity in the adult CPG. As was the case for intact Lymnaea, juvenile semi-intact preparations perform aerial respiration less often than do adults. The difference in excitability between juvenile and adult RPeD1s is therefore not sufficient to cause increased rhythmogenesis. Age-related changes in synaptic connectivity within the respiratory CPG and in peripheral modulation allow respiratory rhythmogenesis to be more easily expressed in adults which may compensate for their decreased dependence on cutaneous respiration as their surface to volume ratio changes as the grow in size.     

Comparisons between brain dopaminergic neurons of juvenile and aged rats: sex-related differences.

It is known that several aspects of dopaminergic neurotransmission deteriorate with advanced age. In the present report, we have studied the possible existence of sexual differences in these aging-induced changes. Thus, we measured several pre- and postsynaptic biochemical parameters, indicative of the activity of dopaminergic neurons, in striatum, limbic forebrain and hypothalamic-anterior pituitary area of aged (24-26 months) and young (2 months) rats of both sexes. Tyrosine hydroxylase (TH) activity, as well as the number of D2-dopaminergic receptors, decreased in the striatum of aged rats, especially in the males in which the decrease in the number of receptors was associated with an increase in their affinity. In addition, the ratio between dopamine (DA) and its intraneuronal metabolite, L-3,4-dihydroxyphenyl-acetic acid (DOPAC), which can be used as an index of neurotransmitter turnover, was increased in aged females in parallel with a decreased DA content. In the limbic forebrain, TH activity was also decreased during aging, but only in males, whereas the DOPAC/DA ratio was increased in females, although in parallel with an increased DOPAC production. Finally, in the hypothalamic-anterior pituitary area, aging only affected the females, in which increased plasma prolactin levels were observed. This effect might be the result of a low responsiveness of pituitary lactotrophs to DA released from hypothalamic neurons, in spite of high prolactin levels producing a constant, although ineffective, stimulation of the activity of these neurons, as reflected by the high DOPAC content and DOPAC/DA ratio observed in the medial basal hypothalamus. In summary, these data allow us to suggest that the activity of brain dopaminergic neurons is modified with aging and there are significant differences as a function of sex and brain area.     

Altered course of the right testicular artery

An unusual course of the right testicular artery was observed during routine dissection of the posterior abdominal wall of a 60-year-old male cadaver. It arose from the abdominal aorta, inferior and posterior to the origin of the right renal artery, and passed posterior to the inferior vena cava and right renal vein; it then arched anterior to the inferior pole of the right kidney and descended anterior to the psoas major muscle, crossing anterior to the genitofemoral nerve, ureter and the proximal part of the external iliac artery. Finally, it passed to the deep inguinal ring and through the inguinal canal to enter the spermatic cord with the other constituents. The left testicular artery arose from the abdominal aorta about 1 cm higher than the right testicular artery and followed a normal course. The embryologic basis and clinical importance of this case are discussed.     

Fixed interval performance in weanling rats: a comparison with adult and senile subjects

Weanling (21 days), adult (100 days) and senescent (26 months) albino rats were submitted for 8 days to a fixed interval 60 second schedule, at a pace of 5 half-hour sessions a day. Temporal regulation indices (Curvature Index of Fry, Kelleher and Cook), overall response rates and running rates depend upon the age of the subjects and rank orderly (weanling greater than adult greater than senile). No significant difference was found for post-reinforcement pause durations. Two weeks after the end of the FI 60 second sessions, the senile subjects were submitted to a FI 120 second schedule for 10 days. The inverse relationship between age and temporal regulation accuracy evidenced in FI 60 seconds is discussed in relationship with classical FI data, factors involved in developmental studies and models for time regulated behavior.     

右肾3支动脉伴右睾丸动脉变异1例

笔者在解剖一老年男性尸体时发现从腹主动脉发出3支右肾动脉并伴右睾丸动脉变异(图A),此种变异少见,报道如下:⑴上支肾动脉最大,起点直径5.52mm,由腹主动     

A comparison of the effects of superior collicular ablation in infant and adult rats

Summary Rats sustaining damage to the superior colliculus in infancy or adulthood and sham-operated controls were tested on two tasks requiring visual orienting to unexpected and expected stimuli, respectively. Experiment 1 measured the distracting effect of novel visual and auditory stimuli presented while the animals traversed a familiar runway. Control rats oriented to the distracting stimulus and had lengthened running times on the trials where it was presented. Rats with lesions of the superior colliculus were less distracted by the appearance of unexpected stimuli than sham operated controls but the severity of this effect depended on modality, and on age at operation. Experiment 2 examined the same animals' ability to detect and respond to a small and expected light that appeared at randomly determined positions around the perimeter of a chamber while the rat was at the centre. Filmed records and analyses of response latencies and errors showed that at low stimulus intensities, the active exploration shown particularly by infant-operated animals resulted in performance that was superior to that of adult-operated animals and, at least in terms of error rate, sham-operated controls. It is concluded that unusual behavioural strategies can explain all the differences between the animals operated at different ages. There was no evidence that novel projections from the retina were responsible.     

Suppression of adult copulatory behaviors following LiCl-induced aversive contingencies in juvenile male rats

Sexually immature juvenile male rats received an injection of .3 M (20 ml/kg) lithium chloride (LiCl) during each of 8-10 pairings (spaced at 2-3-day intervals) with an estrous female. Approximately seven weeks later, these males displayed fewer copulatory behaviors in pairings with estrous females than saline control rats. Noncontingent .3 M LiCl injections administered to juvenile males did not affect adult copulatory behaviors. Males that were either group or individually housed during the retention interval displayed comparable suppression, which suggests that copulatory suppression does not represent a generalized aversion to social interactions with another animal. Males housed during the retention interval in an environment that contained the odors of estrous females also displayed suppression comparable to that of males housed in the absence of such odors. This suggests that the associations that mediate copulatory suppression are not elicited solely by the odor cues of estrous females. These data demonstrate that LiCl-induced aversive contingencies in juvenile male rats subsequently suppress adult copulatory behaviors.     

胎儿与成人角膜组织学比较及其意义

目的：为角膜移植材料的选择提供参考。方法：观察了41只胎儿角膜和18只成人角膜的组织结构，并对其中55例进行了体视学测量。结果：6个月胎儿角膜就厚于成人，主要是角膜基质随胎龄增加增厚明显。角膜基质细胞数面密度随胎龄增长而逐月下降，成人值最小。角膜切片中角膜全长内皮细胞数随胎龄逐月增长，但成人其值低于6月以后的胎儿。以上结果经方差分析，P＜0．0001。结论：作角膜移植术时，应选用至少8个月以上胎儿的角膜。