Effect of chronic treatment with piracetam and tacrine on some changes caused by thymectomy in the rat brain

Thymus Polypeptide Preparation Tactivin Restores Learning and Memory in Thymectomied Rats

We studied the effects of tactivin and splenic polypeptides on learning and memory of thymectomized animals. In 3-week rats, thymectomy blocked active avoidance conditioning. Injections of tactivin (0.5 mg/kg) during 1 month after surgery restored learning capacity; splenic polypeptides were ineffective.

Antidepressant pharmacotherapy: focus on sex differences in neuroimmunopharmacological crossroads

Major depression is a stress-related disorder that shows a clear female preponderance. Sex differences in antidepressant response have been documented in both the clinical and experimental settings. It is of interest that antidepressant drugs exert critical immunotropic influences, mediated by direct and/or compensatory routes; these effects are not completely understood but comprise a matter of intensive investigation. Even though human studies have found only a few sex-related differences in the immunotropic effects of antidepressants, recent experimental evidence in the chronic mild stress model of depression points towards a sexually dimorphic neuroimmune playground in view of chronic antidepressant treatment. Herein, we provide a concise review regarding the effects of antidepressant pharmacotherapy on neuroimmune manifestations by concentrating on intriguing sex differences.

Chronic antidepressant treatment exerts sexually dimorphic immunomodulatory effects in an experimental model of major depression: do females lack an advantage?

Major depression is a stress-related disorder that affects about 20% of the population, with women outnumbering men by 2:1. However, research focusing on stress/antidepressant-related immunomodulation overlooks sex differences, although an established sexual dimorphism also characterizes the immune system. We report for the first time that both chronic clomipramine treatment (10 mg/kg, twice daily) and chronic mild stress (CMS) application in rats, exert sexually dimorphic effects on cellular immunoreactivity (natural killer and lymphokine-activated killer cell cytotoxicity and interleukin-2-induced T-cell proliferation), with females presenting a relatively immunosuppressed phenotype compared to males. Moreover, following chronic antidepressant treatment, thymic monoamines presented sex-related alterations, as well as intriguing associations with peripheral T-cell responses. This study highlights the sex-related effects of chronic clomipramine treatment and CMS application on the cellular arm of immunity, and represents a preliminary exposé of a thymus-dependent route pertaining to the interactions between antidepressants and the immune system.

Interleukin 1 beta enhances conditioned fear memory in rats: possible involvement of glucocorticoids

Central administration of 15 ng interleukin (IL)-1beta in the rat significantly enhanced conditioned fear memory assessed by a passive avoidance task, when retested at 24 and 48 h post-training. Pain threshold was unaffected by 15 ng IL-1beta administration. IL-1beta treatment also increased serum corticosterone. This increase in serum corticosterone was further enhanced in rats given both IL-1beta and footshock. Furthermore, the glucocorticoid receptor antagonist mifepristone blocked IL-1beta-induced elevation in corticosterone and also attenuated the enhanced conditioned fear memory. Central administration of IL-1beta significantly increased prostaglandin E2 and decreased the anti-inflammatory cytokine IL-10 release from whole blood cultures; therefore this treatment appears to be effective in inducing an inflammatory response in both the periphery and the brain. The present study confirms that IL-1beta can enhance conditioned fear memory, an effect which is correlated with changes in glucocorticoid function. This facilitation of defensive behaviour could reflect adaptive responses which may enhance survival during sickness.

Evidence that endogenous thymosin alpha-1 is present in the rat central nervous system

We have previously reported that administration of Thymosin alpha 1 (T-alpha1) can enhance the level of the Nerve Growth Factor and the distribution of its receptor in the developing Central Nervous System (CNS) of rat. To further explore the role of T-alpha1 and verify its presence in cells of rat CNS, we carried out an immunohistochemical study using a polyclonal antibody against T-alpha1. T-alpha1 immunoreactivity was found mainly in neurons of the hippocampus and spinal cord and in several small cells, resembling glial cells, of specific regions of the brain. Moreover, to study whether cerebral cells were receptive to T-alpha1, we injected iodinated T-alpha1 (125I-T-alpha1) i.c.v.. 125I-T-alpha1 labelled neurons were observed in the hypothalamus and septal nuclei. Our results indicate that specific neuronal populations in the rat CNS are able to express and respond to T-alpha1.