KCC3 and KCC4 expression in rat adult forebrain.

Potassium chloride ion cotransporters (KCCs) are part of a family of transporters classically described as being involved in cell volume regulation. Recently, KCC2 has been shown to have a role in the development of the inhibitory actions of amine transmitters, whereas KCC3 also plays a fundamental role in the development and function of the central and peripheral nervous system. We have re-assessed the expression of each of the known KCCs in the rat forebrain using RT-PCR and in situ hybridisation histochemistry. As well as confirming the widespread expression of KCC1 and KCC2 throughout the brain, we now show a more restricted expression of KCC3a in the hippocampus, choroid plexus and piriform cortex, as well as KCC4 in the choroid plexus and the suprachiasmatic nucleus of the hypothalamus. The expression of KCC4 in the latter and KCC2 in the lateral hypothalamic and ventromedial hypothalamic nuclei suggests that these cotransporters may have selective roles in neuroendocrine or homeostatic functions. Finally, we demonstrate the existence of a truncated splice variation of KCC3a in the rat that appears to be expressed exclusively in neurons (as is KCC2), whereas the native form of KCC3a and KCC4 appears to be expressed in glial cells.

Centrally administered galanin-like peptide modifies food intake in the rat: a comparison with galanin.

Galanin-like peptide (GALP) is a recently identified neuropeptide that shares sequence homology with the orexigenic neuropeptide, galanin. In contrast to galanin, GALP is reported to bind preferentially to the galanin receptor 2 subtype (GalR2) compared to GalR1. The aim of this study was to determine the effect of GALP on feeding, body weight and core body temperature after central administration in rats compared to the effects of galanin. Intracerebroventricular (i.c.v.) injection of GALP (1 micro g-10 micro g) significantly stimulated feeding at 1 h in both satiated and fasted Sprague-Dawley rats. However, 24 h after GALP injection, body weight gain was significantly reduced and food intake was also usually decreased. In addition, i.c.v. GALP caused a dose-related increase in core body temperature, which lasted until 6-8 h after injection, and was reduced by peripheral administration of the cyclooxygenase inhibitor, flurbiprofen (1 mg/kg). Similar to GALP, i.c.v. injection of galanin (5 micro g) significantly increased feeding at 1 h in satiated rats. However, there was no difference in food intake and body weight at 24 h, and galanin only caused a transient rise in body temperature. Thus, similar to galanin, GALP has an acute orexigenic effect on feeding. However, GALP also has an anorectic action, which is apparent at a later time. Therefore, GALP has complex opposing actions on energy homeostasis.