Inhibition of apoptosis in chlamydia-infected cells: blockade of mitochondrial cytochrome c release and caspase activation.

We report that chlamydiae, which are obligate intracellular bacterial pathogens, possess a novel antiapoptotic mechanism. Chlamydia-infected host cells are profoundly resistant to apoptosis induced by a wide spectrum of proapoptotic stimuli including the kinase inhibitor staurosporine, the DNA-damaging agent etoposide, and several immunological apoptosis-inducing molecules such as tumor necrosis factor-alpha, Fas antibody, and granzyme B/perforin. The antiapoptotic activity was dependent on chlamydial but not host protein synthesis. These observations suggest that chlamydia may encode factors that interrupt many different host cell apoptotic pathways. We found that activation of the downstream caspase 3 and cleavage of poly (ADP-ribose) polymerase were inhibited in chlamydia-infected cells. Mitochondrial cytochrome c release into the cytosol induced by proapoptotic factors was also prevented by chlamydial infection. These observations suggest that chlamydial proteins may interrupt diverse apoptotic pathways by blocking mitochondrial cytochrome c release, a central step proposed to convert the upstream private pathways into an effector apoptotic pathway for amplification of downstream caspases. Thus, we have identified a chlamydial antiapoptosis mechanism(s) that will help define chlamydial pathogenesis and may also provide information about the central mechanisms regulating host cell apoptosis.

Molecular cloning of a novel hyaluronan receptor that mediates tumor cell motility.

A cDNA encoding a unique hyaluronan receptor has been molecularly cloned from a lambda GT11 3T3 cDNA expression library. Immunoblot analyses of cell lysates, using antibodies to peptides encoded in the cDNA, specifically react with a 58-kD protein. This protein is regulated by the mutant H-ras gene in cells containing a metallothionein promoter H-ras hybrid gene. Further, antibodies to peptide sequences encoded in the cDNA block the increase in locomotion resulting from induction of the mutant H-ras gene in this cell line. In a transblot assay, the bacterially expressed protein binds to biotinylated hyaluronan. Antibodies to peptides encoded in the cDNA react in immunoblot assays with the 58- and 52-kD proteins of a novel hyaluronan receptor complex previously implicated in cell locomotion. Furthermore, antibodies specific to the 58- and 52-kD proteins, which block ras-induced locomotion, also cross-react with the expressed, encoded protein. The gene product described here appears to be a new type of hyaluronan receptor that is involved in cell locomotion. It is named RHAMM, an acronym for receptor for hyaluronan-mediated motility.

Migration of bovine aortic smooth muscle cells after wounding injury. The role of hyaluronan and RHAMM.

The migration of smooth muscle cells is a critical event in the pathogenesis of vascular diseases. We have investigated the role of hyaluronan (HA) and the hyaluronan receptor RHAMM in the migration of adult bovine aortic smooth muscle cells (BASMC). Cultured BASMC migrated from the leading edge of a single scratch wound with increased velocity between 1 and 24 h. Polyclonal anti-RHAMM antisera that block HA binding with this receptor abolished smooth muscle cell migration following injury. HA stimulated the random locomotion of BASMC and its association with the cell monolayer increased following wounding injury. Immunoblot analysis of wounded monolayers demonstrated a novel RHAMM protein isoform that appeared within one hour after injury. At the time of increased cell motility after wounding, FACS analysis demonstrated an increase in the membrane localization in approximately 25% of the cell population. Confocal microscopy of injured monolayers confirmed that membrane expression of this receptor was limited to cells at the wound edge. Collectively, these data demonstrate that RHAMM is necessary for the migration of smooth muscle cells and that expression and distribution of this receptor is tightly regulated following wounding of BASMC monolayers.

B16 melanoma cell arrest in the mouse liver induces nitric oxide release and sinusoidal cytotoxicity: a natural hepatic defense against metastasis.

The formation of liver metastases involves interactions between intravascular cancer cells and the hepatic microvasculature. Here we provide evidence that the arrest of intravascular B16F1 melanoma cells in the liver induces a rapid local release of nitric oxide (NO) that causes apoptosis of the melanoma cells and inhibits their subsequent development into hepatic metastases. B16F1 melanoma cells (5 x 10(5)) labeled with fluorescent microspheres were injected into the portal circulation of C57BL/6 mice. The production of NO in vivo was detected by electron paramagnetic resonance spectroscopy ex vivo using an exogenous NO-trapping agent. A burst of NO was observed in liver samples examined immediately after tumor cell injection. The relative electron paramagnetic resonance signal intensity was 667 +/- 143 units in mice injected with tumor cells versus 28 +/- 5 units after saline injection (P < 0.001). Two-thirds of cells arrested in the sinusoids compared with the terminal portal venules (TPVs). By double labeling of B16F1 cells with fluorescent microspheres and a TdT-mediated UTP end labeling assay, we determined that the melanoma cells underwent apoptosis from 4-24 h after arrest. The mean rate of apoptosis was 2-fold greater in the sinusoids than in the TPVs at 4, 8, and 24 h after injection (P < 0.05-0.01). Apoptotic cells accounted for 15.9 +/- 0.8% of tumor cells located in the sinusoids and 7.1 +/- 0.9% of tumor cells in the TPVs. The NO synthase inhibitor N(G)-nitro-L-arginine methyl ester completely blocked the NO burst (P < 0.001) and inhibited the apoptosis of B16F1 cells in the sinusoids by 77%. However, the rate of tumor cell apoptosis in the TPVs was not changed. There were 5-fold more metastatic nodules in the livers of N(G)-nitro-L-arginine methyl ester-treated mice (P < 0.05). The inactive enantiomer N(G)-nitro-D-arginine methyl ester had no effect on the initial NO burst or on apoptosis of tumor cells in vivo. Both annexin V phosphatidylserine plasma membrane labeling and DNA end labeling of apoptotic cells were demonstrated after a 5-min exposure (a time equivalent to the initial transient NO induction in vivo) of B16F1 cells to a NO donor in vitro. These results identify the existence of a natural defense mechanism against cancer metastasis whereby the arrest of tumor cells in the liver induces endogenous NO release, leading to sinusoidal tumor cell killing and reduced hepatic metastasis formation.

The developmental and neural determinants of the effects of estrogen on feeding behavior in the rat: a theoretical perspective.

Conceptually, the neural regulation of feeding behavior is proposed to be a function of the activities of a long-term (day to day) and a short-term (meal to meal) control system. Although these two control systems are presumably involved in a continuous and dynamic interaction, they can be behaviorally and anatomically separated by specific regulatory challenges and brain lesions. Utilizing this general regulatory model for the hypothalamic control of feeding behavior, the effects of estrogen on a variety of behavioral indices of energy regulation are reviewed and discussed. The effects of ovarian hormones on the feeding behavior of both prepubertal and adult female rats when faced with a series of regulatory tests shown to provide specific information about the long- and short-term control of feeding behavior leads to the following conclusions. Modulation of feeding behavior by ovarian hormones is detectable well before the time of puberty in the female rat and is expressed in terms of a 4-day periodicity that is very similar to adult animals. Estrogen appears to modulate feeding behavior primarily by modifying the long-term control of feeding behavior or else the manner in which nutrients are integrated into this long-term system. It is further proposed that estrogen acts upon metabolically specific and unique neural elements in the hypothalamus whose function is to translate error signals derived from the long-term integration of body nutrients into appropriate readjustments in feeding behavior. Although this dual-regulatory model for the hypothalamic control of feeding behavior can account for the majority of the effects of estrogen on feeding behavior, further studies suggest that an "extrahypothalamic" mechanism must mediate certain aspects of the neural control of feeding behavior as well as the behavioral effects of estrogen. Specifically, the present model system can account for the role of carbohydrates in the neural control of feeding behavior, but fats and possibly proteins can modify feeding behavior independent of the hypothalamus. Likewise, estrogen can influence the efficiency with which nutrient loads of fats and proteins can modify subsequent feeding behavior and therefore this proposed "extrahypothalamic" mechanism may mediate those effects of estrogen on feeding behavior that cannot be accounted for by the present dual-regulatory model.

Origin of insulin-receptive nerve terminals in rat median eminence.

The origin of insulin-receptive axon terminals in the rat median eminence was determined by combining surgical and chemical ablation techniques and the in vivo radioautographic approach, in which labeling of the median eminence with blood-borne [125I]insulin served as a quantifiable marker for the presence of receptive axonal elements. Whereas unilateral deafferentation of the median eminence from the ipsilateral brain produced as much as a 50% ipsilateral loss of insulin-binding sites, transection of axonal projections to median eminence from neurons located lateral to the ventromedial hypothalamic nucleus produced no detectable loss in insulin-binding capacity. Unilateral electrocoagulation of various regions of the medial basal hypothalamus indicated that insulin-receptive axon terminals arise primarily from neurons in and about the hypothalamic arcuate nucleus and from the posterior ventrolateral subdivision of the hypothalamic ventromedial nucleus. A primary site of origin from the arcuate nucleus was confirmed in rats treated neonatally with monosodium L-glutamate, which, in addition to a selective destruction of arcuate neurons, produced a profound reduction in the insulin-specific binding capacity of the median eminence. The results of this study indicate that insulin-binding axon terminals arise from a unique class of tuberoinfundibular neuron with hormone-receptive capacity. These neurons may function to mediate direct interaction of circulating insulin with central autonomical, behavioral, and neuroendocrine systems.

Murine hepatic microvascular adhesion molecule expression is inducible and has a zonal distribution.

The structural and functional heterogeneity of hepatocytes and non-parenchymal cells across the liver lobule or acinus has been well documented. The geographic distribution and potential for induced expression of adhesion molecules on murine hepatic microvascular cells has not been reported, although these molecules are able to influence the metastatic outcome of intravascular cancer cells. We have postulated that the expression of adhesion molecules on these cells is susceptible to regulation by environmental factors and that these molecules have a zonal distribution across the acinus. To test this hypothesis, we injected C57BL/6 mice with bacterial lipopolysaccharide, 1 microg/g body weight, i.p. At various time points (0-48 h) after stimulation, liver tissue sections were prepared for immunohistochemistry. Confocal microscopy was used to detect the expression of vascular cell adhesion molecule-1 (VCAM-1), E-selectin, intercellular adhesion molecule-1 (ICAM-1) and alpha v integrin. The expression patterns were quantitatively measured by histomorphometry. Under basal conditions, ICAM-1 was weakly expressed in terminal portal veins while minimal VCAM-1 and no E-selectin were detected. Following stimulation with lipopolysaccharide, VCAM-1 and E-selectin were expressed on the endothelium of terminal portal veins and on sinusoidal lining cells with significantly stronger expression in the periportal zone than midzone. VCAM-1 expression peaked at 4 h and decreased gradually by 48 h. E-selectin peaked at 2 h and disappeared by 12 h after stimulation. ICAM-1 expression showed a much stronger and more uniform expression across the acinus with the peak reached by 4 h and sustained for longer than 48 h after lipopolysaccharide administration. The alpha v integrin was not detected under basal conditions or after lipopolysaccharide stimulation. Expression of all these adhesion molecules (ICAM-1, VCAM-1, E-selectin and alpha v integrin) was induced by growth of B16F1 melanoma cells in the peritoneal cavity of the mouse. These results support the hypotheses that expression of microvascular adhesion molecules in the mouse liver is susceptible to regulation by environmental stimuli and has a zonal heterogeneity across the acinus.

Regulation of B16F1 melanoma cell metastasis by inducible functions of the hepatic microvasculature.

We have previously shown that circulating intravascular cells generally arrest by mechanical restriction in the hepatic sinusoids, causing rapid release of nitric oxide (NO) which is cytotoxic to these cells and inhibits their growth into metastatic tumours. Here, we present evidence that these NO-dependent cytotoxic mechanisms are susceptible to upregulation by lipopolysaccharide (LPS). Five x 10(5) fluorescently labelled melanoma cells were injected into the mesenteric vein of C57BL/6 mice to effect their localisation in the hepatic microvasculature. Test mice were then given 1 mg/kg LPS intraperitoneally (i.p.) to activate the microvascular cells. By electron paramagnetic resonance (EPR) spectroscopy, the expression of NO in the liver was significantly increased by 8 h in the LPS-treated mice. The non-selective NO synthase inhibitor L-NAME inhibited the induction of NO by LPS, while its inactive enantiomer D-NAME had no significant effect. Using immunohistochemistry (IHC), iNOS-positive microvascular cells were detected in the terminal portal venule (TPV) region of the liver 8 h after LPS stimulation. LPS treatment also increased the retention of melanoma cells in the liver between 8 and 24 h, especially in the TPV region. Eight hours after cell injection, local expression of VCAM-1 and ICAM-1 was detected by double-label immunohistochemistry at the sites of tumour cell arrest. Expression of these adhesion molecules was enhanced in mice treated with LPS. Using flow cytometry, 98% of the B16F1 melanoma cells expressed VLA-4, the counter receptor of VCAM-1, and approximately 1.5% expressed LFA-1, the counter receptor of ICAM-1. LPS did not significantly alter the expression of either counter receptor on melanoma cells in vitro or in vivo. By DNA end-labelling, the rates of melanoma cell apoptosis were significantly increased from 8 to 24 h in the TPV region (but not in the sinusoids) of LPS-treated mice. Fourteen days after tumour cell injection, the LPS-treated mice had a significantly smaller hepatic metastatic tumour burden than the control mice. These data suggest that LPS can inhibit the metastasis of melanoma cells in the liver by inducing the expression of NO and adhesion molecules by the hepatic endothelium. The induction of iNOS and the inducible cytotoxic effect of LPS appear to be primarily located within the TPV region of the liver acinus.

Enhanced immunohistochemical detection of autonomic nerve fibers, cytokines and inducible nitric oxide synthase by light and fluorescent microscopy in rat spleen.

We have developed enhanced immunohistochemical protocols for detecting autonomic nerve fibers and splenocyte-associated proteins in rat spleen. This includes norepinephrine-synthesizing enzymes (dopamine-beta hydroxylase (DBH) and tyrosine hydroxylase (TH)), neuropeptide Y (NPY), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), c-fos protein, inducible nitric oxide synthase (iNOS), and the macrophage cell marker ED1. Animals were divided into sham-operated and splenic nerve-sectioned groups for detection of DBH, TH, and NPY. For immunodetection of TNF-alpha, iNOS, IFN-gamma and c-fos, animals were injected IV with saline or 100 microg of lipopolysaccharide (LPS) and were sacrificed at various time intervals post injection. Rats were perfused with 4% paraformaldehyde, spleens removed and cryoprotected, and 50-microm floating sections were cut on a freezing microtome. Immunodetection was performed with various detection systems and substrate/chromogen solutions, and in some cases using pretreatment with proteinase K (PK) for antigen unmasking. PK pretreatment increased immunostaining for DBH, TH, NPY, IFN-gamma, iNOS, and ED1, and the improvement was concentration-dependent. Using NPY immunostaining to index the signal-to-noise ratio for various substrates and detection systems, we found that an alkaline phosphatase detection system with NBT/BCIP as a substrate was the best procedure for light microscopy, whereas the CY3-labeled secondary antibody technique proved optimal for fluorescent microscopy. Surgical transection of the splenic nerve eliminated all nerve fiber staining for DBH, TH, and NPY. TNF-alpha, IFN-gamma, c-fos, and iNOS proteins were observed in the spleen in a time-dependent manner after LPS stimulation. Fluorescent double labeling, visualized with fluorescent confocal scanning laser microscopy, revealed many NPY fibers distributed among the ED1-labeled macrophages. These results demonstrate that immunohistochemistry can be used to index the activational effects of an immune challenge on splenocytes in situ and verifies that splenic immune cells are innervated by the sympathetic nervous system.

Double-labeling of neuropeptide Y-immunoreactive neurons which project from the geniculate to the suprachiasmatic nuclei.

A projection from the ventral geniculate area to the suprachiasmatic nuclei (SCN) has been demonstrated in rats and hamsters. Large lesions in this area of the geniculate cause a dramatic decrease in neuropeptide Y-immunoreactivity in the SCN. Since numerous neuropeptide Y-immunoreactive neurons are found in the lateral geniculate area, we and others proposed that these immunoreactive neurons project to the SCN. In the present study, neurons in the lateral geniculate area of golden hamster brains were examined for both neuropeptide Y-immunoreactivity and a retrograde tracer transported from the SCN. Two days after a pressure injection of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the SCN of hamsters, labeled neurons were found in the intergeniculate leaflet and in the external lamina of the anterior ventral lateral geniculate nucleus (VLGN). These neurons were compared with similarly located neurons which showed immunoreactivity for neuropeptide Y. Morphometric comparisons of neuropeptide Y- and WGA-HRP-labeled neurons indicated that they were comparable in terms of soma size, number of dendrites, orientation and location. In additional hamsters, neurons double-labeled with a retrograde tracer and neuropeptide Y-immunoreactivity were localized in the intergeniculate leaflet and in the external lamina of the anterior VLGN. These results demonstrate that many neuropeptide Y-immunoreactive neurons located in both the intergeniculate leaflet and in the external lamina of the anterior VLGN project to the SCN in hamsters.

The effect of lactation on induced Fos-like immunoreactivity in the rat hypothalamic paraventricular nucleus.

Lactating rats display a period of blunted hypothalamo-pituitary-adrenal (HPA) response to a variety of stressors. This hyporesponsiveness is reported to be dependent upon continuous mother-pup interactions. In this study, computer-assisted densitometric methods were used to measure levels of induced Fos-like immunoreactivity (FLI) in the hypothalamic paraventricular nucleus (PVN) of lactating and non-lactating rats. Adrenalectomy (ADX) induces elevated levels of FLI in the PVN of non-lactating rats. We have observed that, between post-partum day (pd) 4 and pd 21, the level of ADX-induced FLI in the PVN of lactating rats follows a U-shaped distribution; that the persistence of this phenomenon is dependent upon continued mother-pup interaction and that sustained mother-pup interaction beyond the end of the normal suckling period (pd 21) does not extend the period of refractoriness. We have further determined that both the non-specific neural activator Metrazole, and the glutamate agonist N-methyl-D,L-aspartate (NMA), induced smaller increases in FLI in the PVN of lactating rats compared to non-lactating cohorts, and that the suppressing effect of lactation on Metrazole-induced FLI does not extend to all brain regions. These results suggest that mechanisms responsible for the onset and maintenance of the so-called lactational stress-hyporesponsive period (LSHRP) include altered function of glutamatergic pathways.

Interleukin-2 and -6 induce behavioral-activating effects in mice.

Interleukin (IL)-1, IL-2 and IL-6 influence central monoamine activity in a cytokine-specific manner. We demonstrated that whereas IL-2 increased hypothalamic and hippocampal norepinephrine (NE) utilization, and DA turnover in the prefrontal cortex, IL-6 induced profound elevations of serotonin (5-HT) and mesocortical dopamine (DA) activity in the hippocampus and prefrontal cortex [S. Zalcman, J.M. Green-Johnson, L. Murray, D.M. Nance, D.G. Dyck, H. Anisman, A. H. Greenberg, Cytokine-specific central monoamine alterations following IL-1, -2 and -6 administration, Brain Res. 643 (1994) 40-49]. IL-1, in contrast, induced a wide range of central monoamine alterations. We presently report that these cytokines also differentially influence behavior. Profound reductions in non-ambulatory and ambulatory exploration were induced in BALB/c mice following IL-1 administration. In contrast, IL-2-treated mice displayed significant increases in the time spent engaged in non-ambulatory exploration, digging, rearing (particularly the number of free rears), and in the investigation of a novel stimulus (i.e., increased number and duration of stimulus contacts). IL-6-treated mice, moreover, exhibited significant increases in the time spent engaged in ambulatory exploration, digging and rearing (particularly the number of free rears, which tended to be of short duration). Modest increases in locomotion and grooming were also observed in IL-6-treated animals. Plasma corticosterone levels did not vary significantly as a function of IL-6 treatment. Hence, cytokine-specific behavioral-activating effects were induced following administration of IL-2 and IL-6. We suggest that these effects have adaptive significance and relevance to sickness behavior; however, pathological outcomes (e.g., schizophrenia, anxious-like states, anxious depression, motor abnormalities) could develop should these cytokines be overproduced or dysregulated.

Cytokine-specific central monoamine alterations induced by interleukin-1, -2 and -6.

Cytokine-specific alterations of monoamine activity were evident in the hypothalamus, hippocampus and prefrontal cortex 2 h following peripheral administration of recombinant interleukin (IL)-1 beta, IL-2 and IL-6 (200 ng, i.p.) in male, BALB/c mice. IL-1 induced the broadest range of neurochemical changes, affecting central norepinephrine (NE), serotonin (5-HT) and dopamine (DA) activity. In particular, IL-1 enhanced NE turnover in the hypothalamus and hippocampus, 5-HT turnover in the hippocampus and prefrontal cortex (owing to increased utilization and reduced content of the transmitters in these brain regions), and enhanced DA utilization in the prefrontal cortex. IL-6 increased 5-HT and DA activity in the hippocampus and prefrontal cortex in a manner similar to IL-1, but failed to affect central NE activity. Moreover, IL-2 increased hypothalamic NE turnover (reflecting a profound increase in NE utilization) and enhanced DA turnover in the prefrontal cortex, but did not influence central 5-HT activity. Hence, these cytokines differentially altered neurochemical activity in brain regions that mediate neuroimmune interactions and that are influenced by physical and psychological stressors. In addition to the neurochemical changes, plasma corticosterone concentrations were profoundly enhanced in IL-1-treated animals, but not significantly altered by IL-2 or IL-6 treatment. The IL-1-induced corticosterone elevations did not significantly correlate with alterations of hypothalamic NE activity.

Anomalous adrenalectomy-induced Fos-like immunoreactivity in the hypothalamic paraventricular nucleus of stress-hyporesponsive rats.

Cellular activity in the paraventricular nucleus of the hypothalamus (PVN) in response to adrenalectomy (ADX) and sham-ADX was measured in adult male rats, lactating females, and nursing pups using c-fos immunocytochemistry. Increased Fos-like immunoreactivity (FLI) was seen in the PVN of male rats at 4 h following ADX or sham-ADX but this increase was transient, and basal values were restored within 24 h. In suckling pups, ADX induced a marked FLI response in the PVN at 3 days and at 18 days postpartum. At 11 days postpartum, however, the FLI response was attenuated relative to adult animals, and 3- and 18-day-old pups. Similarly, in nursing mothers, ADX induced FLI at 3 days, but this response disappeared by 7 days and did not reappear by the end of the suckling period (day 21). These data indicate that c-fos expression is a sensitive indicator of hyporesponsiveness in the hypothalamic-pituitary-adrenal (HPA) system.

Sexually dimorphic MK801-induced c-fos in the rat hypothalamic paraventricular nucleus.

MK801 induces Fos-like immunoreactivity (FLI) in the paraventricular nucleus (PVN) in a sex, age, hormone and dosage dependent manner. MK801 (1.0 mg/kg) elicited greater behavioural disruption, but less FLI in the PVN of cycling and lactating female rats, compared to like-treated males. Results from gonadectomized rats with or without acute steroid replacement resembled those seen in intact rats but sex differences were extinguished. At a lower dose (0.1 mg/kg), behavioural effects were diminished but females exhibited more behavioural disruption. At this dose however, more FLI was seen in the PVN of females compared to males, but only male-lactating female differences were significant. Taken together, the data suggest that the action of MK801 on the PVN is influenced by gonadal steroids.

Frontolateral hypothalamic knife cuts: interruption of paraventricular efferents to the thoracolumbar cord.

Bilateral thoracolumbar cord injections of the fluorescent tracer bisbenzimide produced extensive retrograde labelling of cell bodies in the paraventricular nucleus of the hypothalamus. Unilateral retrochiasmatic knife cuts (1.5 mm radius) located anterolateral to the paraventricular nucleus dramatically reduced or eliminated the labelling of paraventricular neurons on the ipsilateral side following bilateral bisbenzimide injections into the thoracolumbar cord. Thus paraventricular efferents to the thoracolumbar cord must project in a lateral direction at the level of the nucleus prior to descending toward the spinal cord. Changes in endocrine function, reproductive and feeding behavior reported following similar hypothalamic knife cuts may be related to this efferent system.

Non-overlapping thalamocortical projections for separate forepaw digits before and after cortical reorganization in the raccoon.

The fluorescent dye retrograde tracing technique was used to examine the projection from ventroposterior lateral thalamus to primary somatosensory cortex in the raccoon. Results are presented from fifteen experiments using Fast Blue in combination with either Nuclear Yellow or Diamidino Yellow Dihydrochloride. Injections of two dyes into adjacent but separate digit regions of cortex produced single-labeling of thalamic neurons, suggesting that projections for each digit are separate and independent with no branching to adjacent parts of the somatotopic map. Double-labeling was only seen when the cortical injection sites were overlapping. Similar results were seen in six cases in which amputation of the 5th digit of the contralateral forepaw was carried out four months earlier. These results suggest that neither the strengthening of existing collaterals nor growth of new collaterals in the thalamocortical projection are likely to be responsible for the physiological reorganization that is seen in raccoon cortex after peripheral deafferentation.

Female sexual behavior in the golden hamster following kainic acid lesions in the lateral septal area.

Patterns of female sexual behavior in the hamster are qualitatively different from that observed in the rat. Hamsters demonstrate tonic immobility and a sustained lordotic response that can last for several minutes following minimal stimulation from the male while in rats, the lordotic response is highly dependent upon continued stimulation from the male and lasts for only a few seconds following a mount or intromission. Also, the hamster requires both estrogen and progesterone priming in order to display female sexual behavior but the rat can show lordotic behavior following treatment with estrogen alone. Electrolytic lesions in the lateral septal area of female rats produce a facilitation in female sexual behavior and increase behavioral sensitivity to estrogen. However, lesions in the lateral septal area of rats produced by the neurotoxin kainic acid (KA) result in deficits in female sexual behavior following estrogen and progesterone treatment. Given these species differences in sexual behavior, we have examined the effects of KA lesions in the lateral septal area of hamsters on female sexual behavior. Adult female golden hamsters were ovariectomized and tested for female sexual behavior prior to receiving brain surgery. For all behavior tests, animals were injected SC with 60 micrograms of estradiol benzoate/kg per day for two days and 0.5 mg of progesterone three hours prior to the behavior test on day three. Behavior tests consisted of placing the test animal in a male's home cage for 10 minutes and recording the latency to the first lordosis, length of the longest single bout of lordosis and total lordosis duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Ipsilateral hypothalamic deafferentation blocks the increase in serum FSH following hemi-castration.

In two experiments hypothalamic hemi-islands or sham surgeries were produced on the right side of prepubertal male rats with an extrudable Halàsz-type knife (1.5 mm radius). Animals were then sham castrated or else hemi-castrated on the contralateral or ipsilateral side with respect to brain surgery. Eight or 21 days later, hemi-castrated rats given sham knife cuts showed a significant increase in serum FSH, relative to sham animals with intact testes. Also, animals given hypothalamic hemi-islands and hemi-castrated on the contralateral side showed a significant increase in serum FSH comparable to that seen in hemi-castrated rats with sham brain surgeries. However, hypothalamic hemi-island rats which were hemi-castrated on the ipsilateral side failed to show an increase in serum FSH and were similar to sham operated controls with both gonads. Serum LH levels were comparable among all groups, verifying a clear dissociation between LH and FSH secretion associated with hemi-castration in prepubertal males. In addition, the differences between contralateral and ipsilateral hemi-castrated animals with identical unilateral brain surgeries strongly suggest that FSH release is, in part, under direct neural control. However, in a third experiment, differences in FSH release between ipsi- and contralateral hemi-castrated rats were not found in animals with hypothalamic hemi-islands on the left side of the brain. Thus the hypothalamus may be asymmetrically involved in various components of neuroendocrine control.

Similar effects of estrogen and lateral hypothalamic lesions on feeding behavior of female rats.

Many similarities exist between the inhibitory influence of estrogen on food intake (FI) and body weight (BWt) in female rats and the effect of lateral hypothalamic (LH) lesions on energy balance. Thus, a possible interaction of small electrolytic LH lesions (0.8 mA/10 sec) with hormone-dependent changes in FI, BWt and feeding patterns of female rats was examined. Relative to sham operated controls, rats with LH lesions showed a transitory period of anorexia and initial loss of BWt. Subsequently, FI and BWt gains of lesioned rats returned to control levels although a small chronic reduction in mean BWt was observed relative to sham animals. Daily changes in FI and BWt during 4-day estrous cycles as well as post-ovariectomy increases in FI and BWt were comparable for lesion and sham animals. Also, both groups showed a similar decrease in FI and BWt following a SC injection of estradiol benzoate (EB). Possible effects of LH lesions were further examined by analyzing feeding patterns. Feeding behavior was continuously monitored with photodetectors and recorded on an Esterline Angus event marker before and after a single SC injection of 6 micrograms of EB. Relative to shams, LH animals showed an exaggerated diurnal distribution of meals, ate smaller meals of shorter duration and had larger intervals between meals during the light period. EB was found to shift the feeding patterns of sham animals towards the meal patterns shown by the lesioned rats (exaggerated diurnal distribution of meals, etc.). However, the lesioned rats also showed a normal change in feeding patterns following EB, albeit these changes occurred from a markedly different baseline level.(ABSTRACT TRUNCATED AT 250 WORDS)