Fasting: a major limitation for resistance exercise training effects in rodents.

Protocols that mimic resistance exercise training (RET) in rodents present several limitations, one of them being the electrical stimulus, which is beyond the physiological context observed in humans. Recently, our group developed a conditioning system device that does not use electric shock to stimulate rats, but includes fasting periods before each RET session. The current study was designed to test whether cumulative fasting periods have some influence on skeletal muscle mass and function. Three sets of male Wistar rats were used in the current study. The first set of rats was submitted to a RET protocol without food restriction. However, rats were not able to perform exercise properly. The second and third sets were then randomly assigned into three experimental groups: 1) untrained control rats, 2) untrained rats submitted to fasting periods, and 3) rats submitted to RET including fasting periods before each RET session. While the second set of rats performed a short RET protocol (i.e., an adaptation protocol for 3 weeks), the third set of rats performed a longer RET protocol including overload (i.e., 8 weeks). After the short-term protocol, cumulative fasting periods promoted loss of weight (P<0.001). After the longer RET protocol, no difference was observed for body mass, extensor digitorum longus (EDL) morphology or skeletal muscle function (P>0.05 for all). Despite no effects on EDL mass, soleus muscle displayed significant atrophy in the fasting experimental groups (P<0.01). Altogether, these data indicate that fasting is a major limitation for RET in rats.

Exploratory studies of the potential anti-cancer effects of creatine.

Two experiments were performed, in which male Wistar Walker 256 tumor-bearing rats were inoculated with 4 × 10(7) tumor cells subcutaneously and received either creatine (300 mg/kg body weight/day; CR) or placebo (water; PL) supplementation via intragastric gavage. In experiment 1, 50 rats were given PL (n = 22) or CR (n = 22) and a non-supplemented, non-inoculated group served as control CT (n = 6), for 40 days, and the survival rate and tumor mass were assessed. In experiment 2, 25 rats were given CR or PL for 15 days and sacrificed for biochemical analysis. Again, a non-supplemented, non-inoculated group served as control (CT; n = 6). Tumor and muscle creatine kinase (CK) activity and total creatine content, acidosis, inflammatory cytokines, and antioxidant capacity were assessed. Tumor growth was significantly reduced by approximately 30 % in CR when compared with PL (p = 0.03), although the survival rate was not significantly different between CR and PL (p = 0.65). Tumor creatine content tended to be higher in CR than PL (p = 0.096). Tumor CK activity in the cytosolic fraction was higher in CR than PL (p < 0.0001). Blood pCO2 was higher in CT and CR than PL (p = 0.0007 and p = 0.004, respectively). HCO3 was augmented in CT compared to PL (p = 0.03) and CR (p = 0.001). Plasma IL-6 was lower and IL-10 level was higher in CR than PL (p = 0.03 and p = 0.0007, respectively) and TNF-alpha featured a tendency of decrease in CR compared to PL (p = 0.08). Additionally, total antioxidant capacity tended to be lower in CT than PL (p = 0.07). Creatine supplementation was able to slow tumor growth without affecting the overall survival rate, probably due to the re-establishment of the CK-creatine system in cancer cells, leading to attenuation in acidosis, inflammation, and oxidative stress. These findings support the role of creatine as a putative anti-cancer agent as well as help in expanding our knowledge on its potential mechanisms of action in malignancies.

Blood flow restricted resistance training attenuates myostatin gene expression in a patient with inclusion body myositis.

UNLABELLED: Inclusion body myositis is a rare idiopathic inflammatory myopathy that produces extreme muscle weakness. Blood flow restricted resistance training has been shown to improve muscle strength and muscle hypertrophy in inclusion body myositis. OBJECTIVE: The aim of this study was to evaluate the effects of a resistance training programme on the expression of genes related to myostatin (MSTN) signalling in one inclusion body myositis patient. METHODS: A 65-year-old man with inclusion body myositis underwent blood flow restricted resistance training for 12 weeks. The gene expression of MSTN, follistatin, follistatin-like 3, activin II B receptor, SMAD-7, MyoD, FOXO-3, and MURF-2 was quantified. RESULTS: After 12 weeks of training, a decrease (25%) in MSTN mRNA level was observed, whereas follistatin and follistatin-like 3 gene expression increased by 40% and 70%, respectively. SMAD-7 mRNA level was augmented (20%). FOXO-3 and MURF-2 gene expression increased by 40% and 20%, respectively. No change was observed in activin II B receptor or MyoD gene expression. CONCLUSIONS: Blood flow restricted resistance training attenuated MSTN gene expression and also increased expression of myostatin endogenous inhibitors. Blood flow restricted resistance training evoked changes in the expression of genes related to MSTN signalling pathway that could in part explain the muscle hypertrophy previously observed in a patient with inclusion body myositis.

Protein turnover, amino acid requirements and recommendations for athletes and active populations.

Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ((13)C-lysine, (15)N-glycine, ²H5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g · kg(-1) · day(-1) compared to 0.8 g · kg(-1) · day(-1) in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

Short- and long-term changes in gastric morphology and histopathology following sleeve gastrectomy in diet-induced obese rats.

BACKGROUND: Sleeve gastrectomy (SG) has been used as a multipurpose surgical procedure for the treatment of morbid obesity. The aim of the study was to analyze gastric morphology and histology at two different time points after SG in rats. METHODS: Thirty-five male Wistar rats were fed ad libitum during 3 months on a high-fat diet to induce obesity. Subsequently, 25 diet-induced obese rats underwent either SG (n = 12) or a sham operation (n = 13). The remaining ten obese animals encompassed the nonoperated control group (Co). Four weeks postoperatively, 15 rats (n = 5 rats/experimental group) were sacrificed, while the remaining 20 rats were sacrificed after 16 weeks (animals/group; Co = 5, sham = 8, SG = 7) to compare the gastric morphological and histopathological changes over time. Body weight and food intake were regularly recorded. RESULTS: For both time periods, the Co groups exhibited the highest body weight, while the rats undergoing the SG showed the lowest weight gain (P < 0.05). Initially, significant differences (P < 0.005) in food intake relative to body weight were observed between the Co rats and animals undergoing surgery, which disappeared thereafter. The actual total stomach size after both experimental periods in the SG group was similar to that of non- and sham-operated rats mainly due to a forestomach enlargement, which was more pronounced after 16 weeks. Traits of gastritis cystica profunda characterized by gastric foveolae elongation with hyperplasia and cystic dilatation of the glands were observed in the residual stomachs of the sleeve-gastrectomized rats. These findings were mostly observed after 16 weeks of performing the SG, although they were also detected occasionally following 4 weeks postoperatively. No intestinal metaplasia was observed. CONCLUSION: After SG gastric macro- and microscopic changes with functional implications in both the short and long term take place.

Functional and morphological effects of resistance exercise on disuse-induced skeletal muscle atrophy.

Abstract quality of life. Since there is no currently effective and safe treatment available for skeletal muscle atrophy, the search for new alternatives is necessary. Resistance exercise (RE) seems to be an important tool in the treatment of disuse-induced skeletal muscle atrophy by promoting positive functional (strength and power) and structural (hypertrophy and phenotypic changes) adaptive responses. Human and animal studies using different types of resistance exercise (flywheel, vascular occlusion, dynamic, isometric, and eccentric) have obtained results of great importance. However, since RE is a complex phenomenon, lack of strict control of its variables (volume, frequency, intensity, muscle action, rest intervals) limits the interpretation of the impact of the manipulation on skeletal muscle remodeling and function under disuse. The aim of this review is to critically describe the functional and morphological role of resistance exercise in disuse-induced skeletal muscle atrophy with emphasis on the principles of training.

Exercise training changes IL-10/TNF-alpha ratio in the skeletal muscle of post-MI rats.

Heart failure (HF) is associated with changes in the skeletal muscle (SM) which might be a consequence of the unbalanced local expression of pro- (TNF-alpha) and anti- (IL-10) inflammatory cytokines, leading to inflammation-induced myopathy, and SM wasting. This local effect of HF on SM may, on the other hand, contribute to systemic inflammation, as this tissue actively secretes cytokines. Since increasing evidence points out to an anti-inflammatory effect of exercise training, the goal of the present study was to investigate its effect in rats with HF after post-myocardial infarction (MI), with special regard to the expression of TNF-alpha and IL-10 in the soleus and extensor digitorum longus (EDL), muscles with different fiber composition. Wistar rats underwent left thoracotomy with ligation of the left coronary artery, and were randomly assigned to either a sedentary (Sham-operated and MI sedentary) or trained (Sham-operated and MI trained) group. Animals in the trained groups ran on a treadmill (0% grade at 13-20 m/min) for 60 min/day, 5 days/week, for 8-10 weeks. The training protocol was able to reverse the changes induced by MI, decreasing TNF-alpha protein (26%, P<0.05) and mRNA (58%, P<0.05) levels in the soleus, when compared with the sedentary MI group. Training also increased soleus IL-10 expression (2.6-fold, P<0.001) in post-MI HF rats. As a consequence, the IL-10/TNF-alpha ratio was increased. This "anti-inflammatory effect" was more pronounced in the soleus than in the EDL, suggesting a fiber composition dependent response.

Exercise training attenuates lipectomy-induced impaired glucose tolerance in rats.

OBJECTIVE: Since visceral adipose tissue (VAT) may account for impaired peripheral and hepatic insulin sensitivity (IS), it has been hypothesized that the partial removal of VAT could result in improved insulin action, while the re-growth of the excised tissue and/or compensatory growth of non-excised depots seems to occur. Thus, it was aimed to investigate whether or not VAT removal and exercise affect IS. METHODS: Male Wistar rats were fed a high-fat diet and subsequently assigned randomly to one of four groups: 1. exercised plus lipectomized (EL), 2. exercised plus sham-lipectomized (ES), 3. sedentary plus lipectomized (CL), 4. sedentary plus sham-lipectomized (CS). After lipectomy, EL and ES animals underwent a 7-consecutive-day training period. Body weight, food intake, basal metabolic rate, fasting glucose, and glucose tolerance were assessed before and after the interventions. Fasting insulin and the HOMA index, body fat mass, and the expression of pro-inflammatory genes were assessed after the interventions. RESULTS: EL group showed greater insulin sensitivity compared to all other groups. EL and ES groups showed lower fasting insulin levels when compared to CL and CS groups, respectively. The EL group showed improved IS when compared to the remaining groups. The CL group showed impaired glucose tolerance and increased TNF-alpha gene expression. Body weight and fat mass did not differ among the groups. PPAR gamma gene expression was increased in the EL and ES groups. CONCLUSIONS: These results showed that short-term swimming training improved insulin sensitivity, but failed to prevent fat regain in lipectomized animals. Lipectomy induced impaired glucose tolerance, which is probably related to increased TNF-alpha gene expression. It is possible that a high-fat diet might be implicated in faster regain of adipose tissue after lipectomy. Our results also show that short-term exercise associated with lipectomy could improve insulin sensitivity.

Characteristics of women who frequently under report their energy intake: a doubly labelled water study.

BACKGROUND/OBJECTIVES: We applied three dietary assessment methods and aimed at obtaining a set of physical, social and psychological variables that can discriminate those individuals who did not underreport ('never under-reporters'), those who underreported in one dietary assessment method ('occasional under-reporters') and those who underreported in two or three dietary assessment methods ('frequent under-reporters'). PARTICIPANTS/METHODS: Sixty-five women aged 18-57 years were recruited for this study. Total energy expenditure was determined by doubly labelled water, and energy intake was estimated by three 24-h diet recalls, 3-day food records and a food frequency questionnaire. A multiple discriminant analysis was used to identify which of those variables better discriminated the three groups: body mass index (BMI), income, education, social desirability, nutritional knowledge, dietary restraint, physical activity practice, body dissatisfaction and binge-eating symptoms. RESULTS: Twenty-three participants were 'never under-reporters'. Twenty-four participants were 'occasional under-reporters' and 18 were 'frequent under-reporters'. Four variables entered the discriminant model: income, BMI, social desirability and body dissatisfaction. According to potency indices, income contributed the most to the total discriminant power, followed in decreasing order by social desirability score, BMI and body dissatisfaction. Income, social desirability and BMI were the characteristics that mainly separated the 'never under-reporters' from the under-reporters (occasional or frequent). Body dissatisfaction better discriminated the 'occasional under-reporters' from the 'frequent under-reporters'. CONCLUSIONS: 'Frequent under-reporters' have a greater BMI, social desirability score, body dissatisfaction score and lower income. These four variables seemed to be able to discriminate individuals who are more prone to systematic under reporting.

Effects of creatine supplementation on glucose tolerance and insulin sensitivity in sedentary healthy males undergoing aerobic training.

Recent findings have indicated that creatine supplementation may affect glucose metabolism. This study aimed to examine the effects of creatine supplementation, combined with aerobic training, on glucose tolerance in sedentary healthy male. Subjects (n = 22) were randomly divided in two groups and were allocated to receive treatment with either creatine (CT) ( approximately 10 g . day over three months) or placebo (PT) (dextrose). Administration of treatments was double blind. Both groups underwent moderate aerobic training. An oral glucose tolerance test (OGTT) was performed and both fasting plasma insulin and the homeostasis model assessment (HOMA) index were assessed at the start, and after four, eight and twelve weeks. CT demonstrated significant decrease in OGTT area under the curve compared to PT (P = 0.034). There were no differences between groups or over time in fasting insulin or HOMA. The results suggest that creatine supplementation, combined with aerobic training, can improve glucose tolerance but does not affect insulin sensitivity, and may warrant further investigation with diabetic subjects.

Effect of arginine, ornithine and citrulline supplementation upon performance and metabolism of trained rats.

During intense exercise there is an augmented production of ammonia and IMP in the exercised muscle that could be related to the establishment of peripheral fatigue. In order to prevent this accumulation, the urea cycle in the liver eliminates ammonia in the form of urea and the skeletal muscle buffers the increase of ammonia via transamination reactions. In the present study we evaluated the effect of arginine, citrulline and ornithine supplementation, intermediates of the urea cycle, on the performance of sedentary and swimming-trained rats submitted to a single bout of exhaustive exercise. We also measured the glycogen content of the soleus and gastrocnemius muscles and of the liver, as well as the plasma concentrations of ammonia, urea, glutamine, glucose and lactate. The results indicate that arginine, citrulline and ornithine supplementation increased the flux of substrate through the reaction catalysed by glutamine synthetase, leading to increased glutamine production after an exhaustive bout of exercise, and of the mechanism involved in ammonia buffering.

Relative reactivity of lysine and other peptide-bound amino acids to oxidation by hypochlorite.

Antibacterial and inflammatory responses of neutrophils and macrophages produce hypochlorite as a major oxidant. Numerous side chains of amino acids found in extracellular proteins can be modified by hypochlorite, including His, Arg, Tyr, Lys, Trp, and Met. We studied the relative reactivity of each of these amino acid residues in short N-blocked peptides, where other residues in the peptide were highly resistant to hypochlorite attack. Hypochlorite treatment led to modified peptides in each case, which were detected by changes in retention on reversed-phase HPLC. A distinct single product, consuming two equivalents of hypochlorite per equivalent of peptide, was obtained from the Lys-containing peptides. UV spectroscopy, nuclear magnetic resonance (NMR), and electrospray/mass spectroscopy identified this product as the dichloramine at the epsilon-amino group of the Lys side chain. The dichloramine at Lys did not decompose to form a detectable amount of carbonyl reactive with dinitrophenylhydrazine. The dichloramine at Lys did however quantitatively revert back to Lys during HCl digestion of the tetrapeptide for amino acid analysis, with simultaneous modification of the adjacent Phe residue. The formation of the dichloramine at Lys was not blocked by peptides or acetylated amino acids that contained Tyr, His, or Arg. In contrast, the presence of equimolar Met-containing peptide, or N-Acetyl-Trp, both inhibited the formation of the dichloramine at Lys. Thus, Met and Trp side chains of proteins might be able to protect Lys from chloramine formation under some circumstances, but this interpretation must consider that Met and Trp are typically found in relatively inaccessible hydrophobic sites, whereas lysine is typically exposed on the protein surface. The hierarchy of amino acid reactivities examined here will aid in the prediction of residues in biological samples most likely to be modified by hypochlorite.

A comparative analysis of somatolactin-related immunoreactivity in the pituitaries of four neopterygian fishes and one chondrostean fish: an immunohistochemical study.

An antiserum to cod somatolactin (SL) was used for immunohistochemical screening for the pars intermedia of two teleosts (Oreochromis mossambicus and Gymothorax meleagris), two holostean fishes (Lepisosteus osseus and Amia calva), and a chondrostean fish (Acipenser fulvescens) for SL-immunopositive (SL-IR) cells. As expected, a subset of the epithelial cells in the pars intermedia of O. mossambicus (tilapia) was immunopositive for SL, and the remainder of the epithelial cells was immunopositive for alpha-MSH-specific antiserum (alpha-MSH-IR). SL-IR was not detected in any of the epithelial cells in the pars intermedia of the moray eel G. meleagris. To determine whether SL-IR could be detected in nonteleost fishes, immunohistochemical analyses were done on the pituitaries of two holostean fishes and one chondrostean fish. In the pars intermedia of the gar, L. osseus, a subset of cells was immunopositive for alpha-MSH only. However, in the pars intermedia of the bowfin, A. calva, all of the epithelial cells indicated the presence of both SL and alpha-MSH. Finally, no SL-positive cells were detected in the pars intermedia of the sturgeon, A. fulvescens.

Effect of aspartate, asparagine, and carnitine supplementation in the diet on metabolism of skeletal muscle during a moderate exercise.

The present study examined the effect of diet supplementation of oxaloacetate precursors (aspartate and asparagine) and carnitine on muscle metabolism and exercise endurance. The results suggest that the diet supplementation increased the capacity of the muscle to utilize FFA and spare glycogen. Time to exhaustion was about 40% longer in the experimental group compared to the control, which received commercial diet only. These findings suggest that oxaloacetate may be important to determine the time to exhaustion during a prolonged and moderate exercise.

Melanotropes of the lizard, Anolis carolinensis, lack N-acetylating mechanisms for both alpha-melanocyte-stimulating hormone and beta-endorphin.

In order to determine whether Anolis carolinensis intermediate pituitary cells have the capacity to N-acetylate either ACTH(1-13)NH2 or beta-endorphin during secretion, individual intermediate pituitary explants were incubated in DMEM/CO2 for 24 h at 28 degrees C. Although alpha-melanocyte-stimulating hormone (alpha-MSH)- and beta-endorphin-related products were spontaneously released into the medium, none of these forms were N-acetylated. It appears that unlike most gnathostomes, A. carolinensis has secondarily lost the POMC-specific N-acetylation mechanisms. A ramification of this observation is that the alpha-MSH for A. carolinensis is ACTH(1-13)NH2.

Pyruvate carboxylase activity in the heart and skeletal muscles of the rat. Evidence for a stimulating effect of exercise.

The mitochondrial pyruvate carboxylase catalyses the ATP-dependent carboxylation of pyruvate to oxaloacetate. Since pyruvate carboxylase generates oxaloacetate for Krebs cycle function, it is proposed that the enzyme activity may be enhanced by exercise. To investigate this proposition, pyruvate carboxylase activity was determined in the heart, soleus and gastrocnemius (white portion) muscles of sedentary and swimming-trained adult rats (1 hour per day, 5 days a week, during 5 weeks) under the following conditions: rest, one hour of exercise and exhaustion. The results show that the pyruvate carboxylase activity is increased during exercise in both the sedentary and trained groups of rats. The stimulatory mechanism is unknown but it is possibly related to the generation of pyruvate from the breakdown of glycogen and acetyl CoA during fatty acid oxidation.

An analysis of the proopiomelanocortin systems in the pituitary of the squamate reptile Lacerta galloti.

Acid extracts of the pars intermedia of the squamate reptile Lacerta galloti were screened for immunoreactive forms of proopiomelanocortin (POMC)-related end products following Sephadex G-50 column chromatography. alpha-MSH-sized end products were detected with a Val-NH2, C-terminal-specific RIA, and beta-endorphin-sized end products were detected with a separate C-terminal-directed RIA. Five peaks of alpha-MSH-related immunoreactivity were isolated following fractionation by reversed-phase HPLC. Based on a comparison of the reversed-phase HPLC properties and the net positive charges (pH 2.75) of the Lacerta forms of alpha-MSH to those of the mammalian forms of alpha-MSH and Anolis carolinensis ACTH(1-13)NH2, it appears that the N-acetylation of alpha-MSH is a major post-translational processing event in the pars intermedia of L. galloti. Although multiple forms of beta-endorphin were detected in the pars intermedia of L. galloti following cation-exchange chromatography, the low levels of N-acetylated beta-endorphin detected with an N-acetyl-specific beta-endorphin RIA indicate that the N-acetylation of beta-endorphin in this species is a minor post-translational processing event. This pattern of POMC processing in the pars intermedia of L. galloti is similar to the processing events observed for the turtle Pseudemys scripta, but distinct from the processing events observed in the squamate reptile A. carolinensis.

Detection of a novel sequence change in the major form of alpha-MSH isolated from the intermediate pituitary of the reptile, Anolis carolinensis.

Intermediate pituitaries of the reptile, Anolis carolinensis, were separately pulse labeled with [3H]Trp and [3H]Tyr. The major form of alpha-MSH was purified by immunoprecipitation and isolated by reverse phase HPLC. Tryptic peptide analysis indicated that the [3H]Trp-labeled C-terminal fragment of Anolis alpha-MSH had the same retention time as mammalian ACTH(9-13) amide; however, the [3H]Tyr-labeled N-terminal fragment did not coelute with either mammalian ACTH(1-8) or N-acetyl-ACTH(1-8). Purification of alpha-MSH from 76 Anolis intermediate pituitaries confirmed that a sequence change had occurred in the N-terminal region of Anolis alpha-MSH. The tissues were acid extracted and purified by Sephadex G-25 chromatography and reverse phase HPLC to yield 4.5 micrograms of purified Anolis alpha-MSH for amino acid composition analysis and automated Edman degradation sequence analysis. The major form of Anolis alpha-MSH is nonacetylated and has the following novel primary sequence: Ser-Tyr-Ala-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro(Val-amide). The presence of Val-amide was verified by immunological analysis, tryptic peptide analysis and amino acid composition analysis.

Presence of substance P and angiotensin II in corticotropic cells of the lizard Gallotia galloti: immunochemical study in the adult and during ontogenesis.

The hypophysis of the lizard Gallotia galloti showed substance-P-like immunoreactivity in both the adenohypophysis (pars distalis, PD; pars intermedia, PI) and the neurohypophysis (median eminence and pars nervosa), whereas angiotensin-II-like immunoreactivity appeared only in PD and PI. The elution-restaining procedure has allowed us to demonstrate the colocalization of both peptides with adrenocorticotropic hormone (ACTH) in PD and PI cells. Electron microscopic study revealed the presence of substance P immunoreactivity on ACTH secretory granules. The ontogeny of both peptides in corticotropic cells has been studied, revealing that the presence of substance P in ACTH-containing cells of the PI occurs from the embryonic stage 33 (S 33), whereas in the PD it occurs from S 34, coinciding with the appearance of ACTH within the same cells. In both median eminence and pars nervosa of the neurohypophysis, substance P appeared later in development, at S 38. Angiotensin II immunoreactivity in PI cells first appeared at S 38, while in PD it appeared from S 40.

Ontogeny and immunohistochemical differentiation of the Pars Tuberalis in the lizard Gallotia gallotti.

The development of the pituitary Pars Tuberalis (PT) was studied in the lizard Gallotia galloti using classical, histological and immunohistochemical techniques. As early as stage 32 of development, the Rathke's pouch exhibits 2 lateral extensions that will give rise to the PT. In these extensions, cellular proliferation results in the formation of two cell masses which develop rostro-laterally and contact the basal diencephalon at stage 35. At stage 37, these two cell groups lose their connection with the pars distalis (PD). Until the end of embryonic development, connective tissue separates the nervous tissue from the glandular one. At hatching, the disappearance of this connective tissue results in the incorporation of the two cell groups into the nervous tissue without visible separation. During development, immunoreactivity for anti-betaLH and anti-TSH appears in the cells of the PT respectively at stage 39 and 37. In adults, almost all cells of the PT can be demonstrated using antisera against gonadotrophins.